VALIDATION GUIDELINES 

FOR AIR SAMPLING METHODS 

UTILIZING CHROMATOGRAPHIC ANALYSIS 

Index no.: T-005 

Version: 3.0 

May 2010 Mary Eide 

 Michael Simmons 

Warren Hendricks 

Methods Development Team 

Industrial Hygiene Chemistry Division 

OSHA Salt Lake Technical Center 

Sandy UT 84070-6406 

1 of 59 
For assistance with accessibility problems in using figures and illustrations presented in these 

guidelines, please contact the Salt Lake Technical Center (SLTC) at (801) 233-4900. This procedure 

was designed and tested for internal use by OSHA personnel. Mention of any company name or 

commercial product does not constitute endorsement by OSHA. 

CONTENTS 

VALIDATION GUIDELINES.......................................................................................................................... 5 

 Preliminary Considerations .............................................................................................................. 5 

 Validation of Analytical Procedure ................................................................................................... 5 

 Validation of Sampling Procedure.................................................................................................... 8 

 Validation of Overall Procedure ..................................................................................................... 19 

PREPARATION OF WRITTEN REPORTS ................................................................................................ 25 

 Fully Validated Methods ................................................................................................................ 25 

 Partially Validated Methods ........................................................................................................... 50 

 Studies ........................................................................................................................................... 55 

 LIST OF FIGURES 

Figure 1. Validation of OSHA methods utilizing chromatographic analysis................................................. 4 

Figure 2. Example of plotted DLAP data...................................................................................................... 7 

Figure 3. Example of a calibration curve...................................................................................................... 7 

Figure 4. Example of breakthrough data.................................................................................................... 10 

Figure 5. Example of plotted data to determine the recommended sampling time and sampling rate...... 14 

Figure 6. Example of a storage test........................................................................................................... 19 

Figure 7. Example of plotted DLOP/RQL data........................................................................................... 20 

Figure 8. Example of a calculated RQL when recovery is the determining factor..................................... 20 

Figure 9. Plot of atmospheric pressure vs. elevation................................................................................. 23 

Figure 3.5.1. Chromatogram obtained at the target concentration with the recommended analytical 

conditions. ................................................................................................................................................... 35 

Figure 3.5.2. Calibration curve for ____ {analyte} ..................................................................................... 35 

Figure 4.1. Plot of data to determine the DLAP. ........................................................................................ 37 

Figure 4.2.1. Plot of data to determine the DLOP/RQL. ............................................................................ 38 

Figure 4.2.2. Chromatogram of the RQL. .................................................................................................. 38 

Figure 4.4.1.1. Ambient storage test for ____ {analyte}. ........................................................................... 39 

Figure 4.4.1.2. Refrigerated storage test for ____ {analyte}...................................................................... 39 

Figure 4.4.2.1. Ambient storage test for ____ {analyte}. ........................................................................... 40 

Figure 4.4.2.2. Refrigerated storage test for ____ {analyte}...................................................................... 40 

Figure 4.7.1. Five-percent breakthrough air volume for ____ {analyte}. ................................................... 42 

Figure 4.7.2. Example of plotted data to determine the recommended sampling rate 

and sampling time ....................................................................................................................................... 43 

Figure 4.10. Mass spectrum of ____ {analyte}. ......................................................................................... 48 

Figure 4.11. The test atmosphere generation and sample collection apparatus....................................... 49 

Figure 1.2.1. Plot of data to determine the DLOP/RQL. ............................................................................ 54 

Figure 1.2.2. Chromatogram of the RQL. .................................................................................................. 54 

 

2 of 59 
INTRODUCTION 

Work performed by the OSHA Methods Development Team usually results in fully validated sampling and 

analytical methods for a single toxic substance or for a group of chemicals that are related to one another. 

When field personnel have a need of to perform workplace monitoring for a certain toxic substance and 

when established methodology does not exist, partially validated methods can be rapidly developed using 

similar, but condensed, evaluation tests as those used for fully validated methods. Validation tests for 

partially validated methods are further described in the section immediately after “PREPARATION OF 

WRITTEN REPORTS FOR FULLY VALIDATED METHODS”. Candidate sampling and analytical 

methods that cannot meet acceptance criteria for validated methods are published in analytical study 

format. Studies are also used to report investigations that involve a class or group of analytes, or an 

aspect of sampling and/or analytical methodology that may be useful for possible future methods 

development work. 

The following guidelines were developed to provide chemists of the Methods Development Team with a 

uniform and practical means for validating sampling and analytical methods that utilize chromatographic 

analysis. The guidelines define sampling and analytical parameters, specify required laboratory tests, 

statistical calculations and criteria for acceptance, and provide a detailed outline for the format of written 

reports for fully validated methods, partially validated methods, and studies. An overview of the 

guidelines is shown in Figure 1. The overall goal of these guidelines is to provide OSHA with sampling 

and analytical methods that can be clearly defended with validation data. The validation tests are 

presented in logical order in these guidelines, but the person performing the validation work can change 

the order in which the tests are completed if so desired. 

These guidelines are open to examination by the OSHA Methods Development Team and refinements 

are officially made on a periodic basis. The resulting evolution in the guidelines is apparent when early 

methods are compared to more recent ones. The validation guidelines have been effectively used and 

refined for more than twenty-five years. 

Fully-validated methods are peer-reviewed by a SLTC methods review committee to assure that methods 

are clearly written and that they comply with the validation tests and acceptance criteria specified in the 

guidelines. The guidelines are used by the review committee to review methods. The methods review 

committee will also verify that any deviation from the guidelines is documented in the method. Partiallyvalidated methods do not have the same status as fully-validated methods and are usually not reviewed 

by the entire methods review committee. 

3 of 59 
PRELIMINARY 

CONSIDERATIONS 

History 

Toxic Effects 

Workplace Exposure 

Physical Properties 

VALIDATION of SAMPLING 

PROCEDURE

VALIDATION of ANALYTICAL 

PROCEDURE 

Analytical Detection Limit 

Instrument Calibration 

Analytical Interferences 

Qualitative Analysis 

Sampler Capacity 

Sampling Rate 

Sampling Interferences 

Extraction Efficiency 

Effects of Storage 

VALIDATION of OVERALL 

PROCEDURE

Overall Detection Limit 

Reliable Quantitation Limit 

Precision 

Reproducibility 

WRITTEN METHOD

Review 

Modification 

Approval 

Figure 1. Validation of OSHA methods utilizing chromatographic analysis. 

4 of 59 
VALIDATION GUIDELINES 

I. Preliminary Considerations 

 A. Review the literature and consult appropriate sources for information on the following: 

 Existing or related sampling and analytical procedures 

 Toxic effects 

 Workplace exposure (what industries and how many people involved) 

 Physical properties and other descriptive information 

 Potential interferences 

 B. Determine the analyte concentration at which the validation will be performed. This value, 

which shall be known as the target concentration, may be an OSHA PEL, an ACGIH TLV, or 

some other concentration for which there is a basis for selection. It may be necessary to 

validate the method at more than one level if the PEL for the analyte has multiple exposure 

limits such as TWA, ceiling, peak, short-term exposure limit, or action level. 

 Consider both active and diffusive samplers for vapors. The ideal goal is to provide sampling 

options for both types of samplers, if possible. Filters or OSHA Versatile Samplers (OVS) are 

to be considered for sampling aerosols or particulates. Active sampling is defined as collection 

of an analyte using a sampling pump to draw air through an appropriate sampling medium such 

as an adsorbent tube or filter. Diffusive sampling is a passive technique that collects the 

analyte using a sampler that employs the principles of diffusion and does not require the use of 

a sampling pump. 

 C. Perform initial tests. Assure that the analytical instrumentation is functioning properly, use 

either a new analytical column or a column that is known to be functioning properly, determine 

analytical conditions, estimate capacity of the selected sampling device, identify possible 

extraction solvents and internal standards (if used) to be tested. If adsorbent tubes and 

diffusive samplers are to be analyzed by GC/FID, first consider 99/1 carbon 

disulfide/dimethylformamide as the extraction solvent. If the resulting extraction efficiency is 

low, test solvent mixtures currently in use at SLTC (i.e., 95/5 ethanol/water, 60/40 

dimethylformamide/carbon disulfide, 95/5 acetone/methanol, 95/5 methylene 

chloride/methanol, or one of several neat solvents) before formulating a new extraction solvent. 

Overall average extraction efficiency greater than 75% is acceptable but an average greater 

than 90% is preferred. 

 D. Use NIST-traceable or other high-quality reagent sources to prepare analytical standards and 

spiked samples. Use reagent-grade chemicals in validation tests and record lot numbers of 

chemicals used in the tests. 

II. Validation of Analytical Procedure 

 A. Detection limit of the analytical procedure (DLAP) 

 Detection limits, in general, are defined as the amount (or concentration) of analyte that gives a 

response (YDL) that is significantly different (three standard deviations (SBR)) from the response 

(YBR) of a reagent blank. 

where SBR is the standard deviation of a reagent blank (1) DL BR =− 3SYY BR YDL is the response at the detection limit 

YBR is the response of the reagent blank 

5 of 59 
 The direct measurement of YBR and SBR in chromatographic methods is typically inconvenient 

and difficult because YBR is usually extremely low. Estimates of these parameters can be made 

with data obtained from the analysis of a series of analytical standards whose responses are in 

the vicinity of the response of a reagent blank. The regression curve obtained for a plot of 

instrument response versus concentration of analyte will usually be linear. If it is clearly 

nonlinear, refer to Burkhart1

 for alternate calculations. Assuming SBR and the precision of data 

about the curve are similar, the standard error of estimate for the regression curve can be 

substituted for SBR in the above equation. The standard error of estimate of a line is the 

mathematical equivalent of the standard deviation for tabulated data. The following 

calculations derive a formula for the detection limit: 

kn

)Y(Y S

2

OBS EST

X(DLAP)Y −

− = ∑ ⋅ (2)

where SY·X(DLAP) is the standard error of estimate 

for the DLAP 

YOBS is observed response 

YEST is estimated response from regression 

curve 

n is total number of data points 

k is 2 for linear regression 

 at point YDL on the regression curve 

 

where YDL is the response at the detection limit 

A is the analytical sensitivity (slope) 

(3) DL D += Y)A(LY BR

LD is the DLAP

YBR is the response of the background 

 substituting for YDL from Equation 1 gives 

where LD is the DLAP 

A

3S

L Y X(DLAP)

D

⋅ (4) = SY·X(DLAP) is the standard error of estimate 

for the DLAP 

A is the analytical sensitivity (slope) 

 Use the following procedure to assure that the concentrations of analytical standards used to 

determine the regression curve will produce responses in the vicinity of the background 

response: 

 1. Estimate the background response near the elution time of the analyte from a reagent 

blank. 

 2. Prepare ten standards, in equally spaced intervals, with the highest standard producing 

a signal about ten times the background response. 

 3. Analyze the ten analytical standards and one reagent blank. 

 

1

 Burkhart, A.J. Appl. Ind. Hyg. 1986, 1, 153-155.

6 of 59 
 4. Determine the regression line 

and then the standard estimate of 

error for the DLAP from the data 

by plotting response versus mass 

injected onto the column. 

Calculate mass injected onto the 

column by multiplying the 

concentration of the standard by 

the volume injected; and then by 

the split ratio (if any). 

 5. Calculate the DLAP using 

Equation 4. Report the DLAP in 

the method as mass of analyte 

injected onto the column. 

 

 6. Prepare a graph of the DLAP 

data as shown in Figure 2 for inclusion in the method. 

0

500

1000

1500

0 150 300 450

DLAP

Mass (pg) Injected onto Column

Area Counts (μV•s)

Figure 2. Example of plotted DLAP data (y = 3.28x + 

20.8). 

 7. The detection limit of the overall procedure (DLOP) and the reliable quantitation limit 

(RQL), described in Sections IV.A and IV.B, can be determined in conjunction with this 

test. 

 B. Instrument calibration 

 Report the standard error of estimate 

(defined as the mass equivalent to 

Sy·x(cal) in Equation 5) from the linear 

regression of data points over a range 

that covers 0.1 (or RQL whichever is 

higher) to 2 times the target 

concentration. If there are several target 

concentrations, select the target 

concentration and the sampler with the 

recommended sampling time and 

sampling rate combination that will 

produce the highest mass loading. The 

regression line is determined from the 

triplicate analysis of analytical standards 

at working range concentrations of 0.1 

(or RQL, whichever is less), 0.5, 1, 1.5, 

and 2 times the target concentration as 

follows: 

0

0.2x105

0.4x105

0.6x105

0.8x105

1.0x105

0 500 1000 1500 2000 2500

Mass (μg) per Sample

Area Counts (μV•s) Figure 3. Example of a calibration curve (y = 38.89x -

65.50).

 1. Prepare and dilute analytical standards as necessary. Analyze each standard three 

times. 

 2. Use the data collected to calculate Sy·x(cal) as shown in Equation 5 and to construct the 

calibration curve (as shown in Figure 3) for inclusion in the method. 

 3. Generate a chromatogram of a standard at the target concentration for inclusion in the 

method. (Section 3.5.1 in the text of the method) 

7 of 59 
 The standard error of estimate is a measure of variation or scatter about the line of regression2

and it is calculated as follows: 

 

where SY·X(CAL) is the standard error of estimate for the 

calibration 

kn

)Y(Y S

2

OBS EST

X(CAL)Y −

− = ∑ ⋅ )5(

YOBS is the observed response 

YEST is estimated response from the regression 

curve 

n is the total number of data points 

k = 2 for linear regression 

k = 3 for quadratic regression 

 

 C. Analytical interferences 

 Analytical interferences become evident if they interfere with quantitation of the analyte. The 

interferences selected for testing should be based, in part, on interferences present in 

workplaces similar to those in which the new method may be used. The literature should also 

be reviewed to identify possible interferences. These potential interferences can often be 

resolved by changing chromatographic conditions or by using a more selective analytical 

detector. 

 1. Determine the effects of suspected interferences by analyzing spiked analytical 

standards. Avoid serious interferences to the analytical method by modifying the 

analytical method or the sampling procedure. 

 2. If a reagent has been added to the sampling medium, generate an additional 

chromatogram at the target concentration for inclusion in the method showing the 

reagent’s relationship to the analyte. (Section 3.5.1) 

 D. Qualitative analysis 

 Present a mass spectrum or alternate chromatographic conditions that will aid in confirming the 

identity or purity of the analyte (or derivative) peak. Mass spectrometry may provide the most 

conclusive identification and shall be addressed in all cases, even if this amounts to an 

explanation why it is not possible or not available. Peak response ratios and analysis with 

alternate detectors may also be useful. Use the format of Section 3.5.1 to present analytical 

conditions with chromatograms, UV spectra, or mass spectra. Include this information in the 

method. (Section 4.10) If the mass spectrum was taken from a spectral library, it is not 

necessary to include analytical conditions. 

III. Validation of Sampling Procedure 

 Use dynamically generated controlled test atmospheres whenever possible to prepare samples for 

validation tests. All test atmospheres generated throughout these validation tests must be noncondensing. It may be necessary, however, to use static test atmospheres such as those prepared in 

gas-sampling bags when safety considerations or other problems prevent use of dynamically 

generated controlled test atmospheres. It might be necessary to use vapor-spiked samples where 

the analyte is volatilized directly upstream of the sampler while drawing air through the sampler. 

Water can be added to the sampler by using humid air in these tests. These alternative and other 

innovative techniques used to prepare samples may require that the analyte be contained in a noninterfering solvent. Gary O. Nelson’s book “Gas Mixtures Preparation and Control” is a useful 

 

2 Arkin, H.; Colton, R.C. Statistical Methods, 5th ed.; Barnes & Noble: New York, 1970; pp 84-88. 

8 of 59 
resource when generating test atmospheres.3

 Procedures used to generate samples should be fully 

described in the backup data section of the validated method. (Section 4.11) 

This section of the guidelines address validation of samplers containing adsorbent media or filters, and 

may require slight modification for validation of more unique samplers such as those utilizing reactive 

reagents, or those containing both adsorbent and filter components such as OSHA Versatile Samplers 

(OVS). Modification may also be required for the validation of bubbler sampling procedures. Consider 

bubblers only as a primary sampling technique of last resort. Specific requirements which apply to the 

validation of diffusive samplers are included in the appropriate sections. The overall extraction 

efficiency, determined in Section III.C, shall be applied to analytical results from capacity, interference, 

and reproducibility validation test results. 

 A. Active samplers 

 1. Sampling rate 

 a. For those substances that have a peak, ceiling, or short-term exposure limit, 

determine the limitations of taking a short-term sample (applicable time from Table 

Z-2 of 29 CFR 1910 or expanded health standards) at the proposed sampling rate. 

If a short-term sample collected at the proposed sampling rate does not result in a 

mass of analyte equal to or greater than 10 times the RQL, study the use of a 

higher flow rate through additional breakthrough studies. For ceiling exposure 

limits listed in Table Z-1 or in expanded standards, determine if 15 min is a 

practical recommended sampling time. 

 b. Select a sampling rate that is suitable for the active sampler. In general, use 50-

200 mL/min for adsorbent tubes and 1-2 L/min for filters and OSHA Versatile 

Samplers (OVS). The sampling rate for samplers that utilize reagent coated 

sampling media may depend on reaction kinetics. The goal is to have a 4-hour 

recommended sampling time for TWA samples. Measure the pressure drop across 

the sampler at each recommended sampling rate and confirm that a sampling 

pump is commercially and commonly available that is capable of maintaining 

constant flow at the measured pressure drop. 

 2. Capacity 

 a. Sampler capacity is defined by the length of time a sampler can be used under a 

set of known test conditions without significant loss of analyte. Capacity can also 

be described as a corresponding air volume or as a collected analyte mass. 

Capacity tests employ only the front adsorbent section of two-section absorbent 

tubes. Use breakthrough tests to determine sampler capacity. Consider 

breakthrough to have occurred when the effluent from the active sampler contains 

a concentration of analyte that is 5% of the upstream concentration (5% 

breakthrough). This can be determined by monitoring the downstream effluent with 

an instrument such as a total hydrocarbon analyzer, a gas chromatograph, or an 

infrared spectrophotometer, after the response of the upstream concentration has 

first been established. When use of an instrument is not possible, breakthrough 

can be determined with a series of backup samplers that are changed at measured 

time intervals. The time intervals will vary with the sampling medium and with the 

analyte, but they must be sufficiently short so that the 5% breakthrough point can 

be accurately determined. Analyze each backup sampler separately. If sampler 

 

3

 Nelson, G.O., Gas Mixtures Preparation and Control, Lewis Publishers, Boca Raton, 1992. 

9 of 59 
capacity is not exceeded after 10 hours of sampling at two times the target 

concentration, discontinue the sampling capacity test and report this fact in the 

method. 

 b. Determine breakthrough at 

ambient temperature from a 

dynamically generated 

controlled test atmosphere 

containing an analyte 

concentration equal to 2 times 

the target concentration. Use 

an absolute humidity for the 

test atmosphere of 15.7 

milligrams of water per liter of 

air (about 80% relative 

humidity at 22.2ΕC). 

 c. Perform three separate 

breakthrough tests to assure 

that sampler capacity has 

adequately been determined. 

0

2

4

6

8

10

0 500 1000 1500

Air Volume (L)

Breakthrough (%)

Figure 4. Example of breakthrough data.

 d. Prepare a plot of breakthrough data for inclusion in the method as shown in Figure 

4. 

 e. Set the recommended sampling time for the method at whichever time is shorter, 4 

hours or 80% of the time required to exceed the capacity of the sampler when 

challenged at two times the target concentration. 

 f. Retention efficiency 

 

 Retention efficiency tests are performed when it is not possible to use a 

dynamically generated controlled test atmosphere. They are designed to provide 

partial support for sampler capacity by showing that analyte when preloaded on the 

sampler is retained when the recommended sampling conditions are used to draw 

humid air through the sampler. 

 

 Perform retention efficiency tests for adsorbent tubes in the following manner: Use 

only the front section of two-section tubes, and spike the sampler in a manner that 

places the analyte at the head of the adsorbent bed. This can be accomplished for 

volatile substances by placing the analyte on the glass wool plug immediately 

ahead of the adsorbent tube while drawing air through the sampler. The analyte 

will be rapidly transferred to the head of the adsorbent bed when the test is started. 

An alternative technique that can be used for less volatile substances is to spike 

the analyte directly onto the head of the adsorbent bed. No more than about 20 μL 

of liquid should be used in these tests. 

 Perform retention efficiency tests for filters and for samplers that contain both a 

filter and an adsorbent (such as OVS tubes) in a similar manner. Be certain to 

spike the samplers in such a way that the analyte is not immediately transferred to 

the support pad or to the absorbent bed. Volatile substances can be spiked on a 

medium that only weakly retains the analyte which is connected in-series upstream 

to the sampling cassette or OVS tube. The analyte will be rapidly transferred to the 

sampler when the test is started. Nonvolatile substances must be directly spiked 

10 of 59 
on the filter surface. This can be accomplished by placing the filter (without any 

support pad) on a suitable support such as the rim of a small beaker so that only 

the outside edge of the filter is supported and then spiking the liquid in about 5-10 

small spots randomly spaced over the face of the filter. This is especially important 

if a reagent is coated on the filter. 

 If filters are used with support pads (back-up pads), they are extracted and 

analyzed separately when retention efficiency tests are performed. If backup pads 

are used, spike six filters and place them in separate sealed cassettes together 

with backup pads for 4 hours with no air drawn through them. These filters will be 

used as controls to determine if the analyte is transferred to the support pad by 

contact without air being drawn through the cassette. 

 

 Perform retention tests as follows: 

 i. Spike six samplers with an amount of analyte equivalent to two times the target 

concentration based on a tentative recommended air volume. Use only the 

front section of two-section adsorbent tubes. Do not spike the samples with 

more than 20 μL of liquid in order to avoid saturation of the sampling medium. 

 ii. Select a recommended sampling rate that is suitable for the samplers. The 

absolute humidity of the air shall be approximately 15.7 milligrams of water per 

liter of air (about 80% relative humidity at 22.2ΕC). The test must be conducted 

for a sufficient time to draw at least 1.25 times the tentative recommended air 

volume through the samplers. 

 iii. Monitor the downstream effluent of the sampler with an instrument as in a 

breakthrough test using a dynamically generated controlled test atmosphere if 

possible. If it is not possible to use an instrument, monitor breakthrough with a 

series of backup samplers that are changed at measured time intervals and 

then analyzed. The time intervals will vary with the sampling medium and with 

the analyte, but they must be sufficiently short so that the 5% breakthrough 

point can be accurately determined. Analyze the spiked samplers at the 

completion of the test. 

 

 iv. Express the analytical results of the backup sampler as percent breakthrough 

by dividing them by the amount spiked on the sampler and plot the results 

against air volume sampled as shown in Figure 4. Report the recovery of the 

spiked samplers determined at the end of the test. 

 

3. Sampling interferences 

Sampling interferences may affect sampler capacity, may chemically react with the 

analyte and affect recovery of the analyte, and may result in analytical interferences. 

The interferences selected for testing should be based, in part, on interferences 

present in workplaces similar to those in which the new method may be used. The 

literature should also be reviewed to identify possible interferences. 

 a. Test for retention of the analyte by using one set of six samplers to sample a 

dynamically generated controlled test atmosphere containing two times the target 

concentration at an absolute humidity of 15.7 milligrams of water per liter of air 

(about 80% relative humidity at 22.2ΕC) for one-quarter of the recommended 

sampling time. Discontinue sampling and set three samplers aside. Flush the 

generation system with contaminant-free air. Contaminant-free air is laboratory 

11 of 59 
conditioned air at known relative humidity but without any added chemical except 

water. Sample the contaminant-free humid air for three-quarters of the 

recommended sampling time using three of the six samplers. Analyze the six 

samplers. Upon analysis, the mean recovery for the second three samplers must 

be greater than 90% of the mean recovery for the first three samples. 

 If the first test fails, repeat the test by using another set of six samplers to sample 

the same dynamically generated controlled test atmosphere but reduce the two 

sampling times by one-half. If the test passes, the new recommended sampling 

time is one-half of the old value. If the mean of the recoveries of the second half of 

the set is still less than 90% of the mean recovery of the first three samples, 

consider retention inadequate and an alternate sampling medium must be found 

and tested. 

 b. Test for the effect of low humidity on analyte recovery by using a set of three 

samplers to sample a dynamically generated controlled test atmosphere containing 

two times the target concentration at an absolute humidity of 3.9 milligrams of 

water per liter of air (about 20% relative humidity at 22.2ΕC) using the 

recommended sampling time. Upon analysis, all three front sections of the 

individual samples shall have collected enough analyte to be greater than 90% of 

the theoretical amount. If not, perform the test at a higher absolute humidity (i.e., 

5.8 milligrams of water per liter of air or about 30% relative humidity at 22.2ΕC) and 

list the restriction in the Special Requirements Section on the cover page of the 

method. 

 

 c. Test for the effect of low concentration on analyte recovery by using a set of three 

samplers to sample a dynamically generated controlled test atmosphere containing 

0.1 times the target concentration at an absolute humidity of 15.7 milligrams of 

water per liter of air (about 80% relative humidity at 22.2ΕC) for the recommended 

sampling time. Upon analysis, all three front sections of the individual samples 

shall have collected enough analyte to be greater than 90% of the theoretical 

amount. If not, an alternate sampling and/or analytical procedure that provides at 

least 90% recovery must be found and tested. 

 d. Test for the effect of at least one suspected chemical sampling interference on 

recovery by using a set of three samplers to sample a dynamically generated 

controlled test atmosphere containing one times the target concentration of the 

analyte at an absolute humidity of 15.7 milligrams of water per liter of air (about 

80% relative humidity at 22.2ΕC) for the recommended sampling time. The 

suspected interference shall be set at an appropriate level which may be its PEL, 

TLV, or level anticipated to be found in the workplace. If more than one 

interference is tested, then the concentration of the interference should be divided 

by the number of interferences so that the sampler will not be overloaded. If two 

interferences are used, each could have a concentration equal to one-half of its 

PEL, TLV, or anticipated level. Upon analysis, all three front sections of the 

individual samplers shall have each collected enough analyte to be greater than 

90% of the theoretical amount of the analyte. If 10% or more of the analyte is 

found on the back section, the recommended sampling time may be too long. 

Repeat the sampler capacity test with the interferences present in the dynamically 

generated controlled test atmosphere, reduce the sampling time, and determine if 

the shorter sampling time is appropriate. 

 

12 of 59 
B. Diffusive samplers 

 1. Sampling rate and capacity 

 It is necessary to generate controlled test atmospheres to determine sampling rates 

and capacities for diffusive samplers. The face velocity of the test atmosphere over the 

samplers should be 0.4 m/second. Before determining sampling rate and capacity, the 

preliminary extraction efficiency from wet absorbent should be determined as follows: 

Calculate the mass of analyte that would be collected on the diffusive sampler after 

sampling a dynamically generated controlled test atmosphere containing the target 

concentration using an approximate sampling rate based on the manufacturer’s 

literature (e.g., SKC is 13 mL/min and 3M is 31 mL/min) for four hours. Spike at least 

two samplers with this amount of analyte and another two samplers with 5% of the 

amount. Upon analysis, the preliminary extraction efficiencies should be sufficiently 

high and within ∀5% of each other. Use the average as the preliminary extraction 

efficiency. After the preliminary sampling rate and preliminary recommended sampling 

time are determined with the preliminary extraction efficiency, perform the final 

extraction efficiency studies in Section III.C. Recalculate the final sampling rate and 

final recommended sampling time using the final extraction efficiency. 

 a. For those substances that have a peak, ceiling, or short-term exposure limit, 

determine the limitations of taking a short-term sample (applicable time from Table 

Z-2 of 29 CFR 1910 or expanded health standards). The shortest recommended 

sampling time for a short-term sample should result in a mass of analyte equal to 

or greater than 10 times the RQL. For ceiling exposure limits listed in Table Z-1, 

determine if 15 min is practical as the recommended sampling time. 

b. Determine sampling rates by using replicate samples to sample a dynamically 

generated controlled test atmosphere for increasing time intervals. Collect three 

samples for each time interval. The time intervals will normally be 5, 10, and 30 

min plus 1, 2, 3, 4, 6, 8, and 10 hours. The concentration of the test atmosphere 

should be two times the target concentration. If the analyte is in Table Z-2 or in an 

expanded standard, use two times the TWA PEL. An absolute humidity of 15.7 

milligrams of water per liter of air (about 80% relative humidity at 22.2 °C) should 

be used. The concentration of the test atmosphere should be verified with an 

alternate method. Two alternate methods are needed if the first alternate method 

does not agree with the theoretical concentration. Alternate methods may include 

an active sampling method and an on-line instrument such as a GC or an IR. The 

theoretical concentration shall be used in subsequent calculations if it is verified. 

Record the temperature and atmospheric pressure inside the chamber. The 

sampler masses are corrected for extraction efficiency as determined in Section 

III.C. Analytical data from only the primary sorbent section of samplers that have a 

secondary sorbent section should be used in these tests. Sampling rate is 

expressed in milliliters per min, and will be calculated by the following equation: 

 

where RSS is sampling rate at sampling site (mL/min) 

E

SS EtC

M1000 )6( R = M is mass collected (μg) 

C is concn of the test atmosphere (μg/L) 

t is sampling time (min) 

13 of 59 

EE is extraction efficiency (decimal form) 

1000 is unit conversion from L to mL 
 c. Convert the ambient sampling rates that are determined at sampling site 

temperature and atmospheric pressure to equivalent sampling rates at NTP 

conditions of 760 mmHg and 298.2 K with the following equation4

: 

 

where RNTP is the sampling rate at NTP conditions 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ =

NTP

SS 2

3

SS

NTP

NTP SS P

P

T

T )7( RR RSS is the sampling rate at sampling site 

TSS is the sampling site temperature in K 

TNTP is 298.2 K 

PSS is the pressure at the sampling site 

PNTP is 760 mmHg

 d. Plot the sampling rates against sampling times as shown Figure 5. Find the 

preliminary sampling rate by averaging the nine values for the 0.5, 1, and 2 hour 

samples (12.2 mL/min). Draw horizontal lines that are 10% above and below the 

preliminary sampling rate (13.42 and 10.98 mL/min). Average all the values from 5 

min to 10 hours that are between the lines to determine the sampling rate. The 

range should contain at least four of the time intervals and the standard deviation 

of the sampling rate should be no more than 5%. Report the mean (12.1 mL/min), 

standard deviation (0.445 mL/min) and the relative standard deviation (3.7%) for all 

the data points used to determine the sampling rate. Report the sampling rate as 

milliliters per min at 760 mmHg and 25 °C and report the range of time it covers for 

example: 5 min to 4 hours. 

Table 1 

Determination of Sampling Rate 

and Recommended Sampling Time 

time (h) first second third 

5 min 12.4 12.5 12.6 

10 min 12.3 12.4 12.5 

0.5 12.1 12.2 12.3 

1 12.0 12.2 12.3 

2 12.1 12.2 12.4 

3 12.0 12.1 12.2 

4 11.8 11.9 12.0 

6 11.4 11.5 11.6 

8 11.2 11.0 11.1 

10 10.2 10.3 10.1 

9

10

11

12

13

14

0 2 4 6 8 10

Time (hours)

Sampling Rate (mL/min)

Figure 5. Example of plotted data to determine the 

recommended sampling time and sampling rate. 

 

 e. To determine the recommended sampling time, use the data from the previous 

paragraph. Sampler capacity is defined to be exceeded when the sampling rate 

appears to decrease rapidly. Sampler capacity was not been exceeded if the 

sampling rate does not appear to decrease. The sampling rate remains constant, 

but analyte can no longer be quantitatively retained because capacity has been 

exceeded. Find the data point with the longest time that is between the horizontal 

lines. Multiply this time by 0.80 to determine the maximum sampling time (6.4 

hours). If this time is greater than 4 hours, the sampling time recommended in the 

method will be 4 hours. This will provide a conservative safety margin when 

samples are taken in complex work atmospheres where substances may compete 

for sites on the adsorbent. 

 

4

 Shulsky, M. “Review of Calculations with Solid Sorbent Passive Monitors to Determine Air Contaminant Concentrations”, OSHA 

Salt Lake Technical Center, Salt Lake City, UT. Unpublished work, 1983. 

14 of 59 
2. Sampling interferences 

 a. Test for reverse diffusion of the analyte by using one set of six samplers to sample 

a dynamically generated controlled test atmosphere containing two times the target 

concentration at an absolute humidity of 15.7 milligrams of water per liter of air 

(about 80% relative humidity at 22.2ΕC) for one-quarter of the recommended 

sampling time. Discontinue sampling and set three samplers aside. Flush the 

generation system with contaminant-free air. Contaminant-free air is laboratory 

conditioned air at known relative humidity but without any added chemical except 

water. Sample the contaminant-free humid air for three-quarters of the 

recommended sampling time with the other three samplers. Analyze the six 

samplers. Upon analysis, the mean recovery for the second three samplers must 

be greater than 90% of the mean recovery for the first three samples. If the test 

passes, the recommended sampling time is the value from the previous paragraph. 

 If the first test fails, repeat the test by using another set of six samplers to sample 

the same dynamically generated controlled test atmosphere but reduce the two 

sampling times by one-half. If the test passes, the new recommended sampling 

time is one-half of the old value. If the mean of the recoveries of the second three 

samplers is still less than 90% of the mean recovery of the first three samples, then 

reverse diffusion is significant and an alternate sampler must be considered. 

 

 b. Test for the effect of low humidity on sampler performance by exposing a set of 

three samplers to a dynamically generated controlled test atmosphere containing 

two times the target concentration at an absolute humidity of 3.9 milligrams of 

water per liter of air (about 20% relative humidity at 22.2ΕC) for the recommended 

sampling time. Upon analysis, all three of the individual samples shall have 

collected enough analyte to be greater than 90% of the theoretical amount. If not, 

perform the test at a higher absolute humidity (i.e., 5.8 milligrams of water per liter 

of air or about 30% relative humidity at 22.2ΕC) and list the restriction in the 

Special Requirements Section on the cover page of the method. Use the average 

diffusive sampling rate determined in Section III.B converted to its equivalent 

sampling rate at sampling site temperature and pressure to calculate results. 

 c. Test for the effect of low concentration on sampler performance by exposing a set 

of three samplers to a dynamically generated controlled test atmosphere containing 

0.1 times the target concentration at an absolute humidity of 15.7 milligrams of 

water per liter of air (about 80% relative humidity at 22.2ΕC) for the recommended 

sampling time. Upon analysis, each of the three individual samples shall have 

collected enough analyte to be greater than 90% of the theoretical amount. If not, 

an alternate sampler must be considered. Use the average diffusive sampling rate 

determined in Section III.B converted to its equivalent sampling rate at sampling 

site temperature and pressure to calculate results. 

 d. Test for the effect of at least one suspected chemical sampling interference on 

recovery by using a set of three samplers to sample a dynamically generated 

controlled test atmosphere containing one times the target concentration of the 

analyte at an absolute humidity of 15.7 milligrams of water per liter of air (about 

80% relative humidity at 22.2ΕC) for the recommended sampling time. The 

suspected interference shall be set at an appropriate level which may be its PEL or 

TLV. If more than one interference is used, then the concentration of the 

interference should be divided by the number of interferences used so that the 

sampler will not be overloaded. If two interferences are used, each could have a 

concentration equal to one-half of its PEL or TLV. Upon analysis, all three samples 

15 of 59 
shall have each collected enough analyte to be greater than 90% of the theoretical 

amount of the analyte. If results are less than 90%, then the recommended 

sampling time may be too long. Repeat the sampler capacity test with the 

interferences present in the atmosphere to determine if a shorter sampling time is 

appropriate. Use the average diffusive sampling rate determined in Section III.B 

converted to its equivalent sampling rate at sampling site temperature and 

pressure to calculate results. 

 C. Extraction efficiency and stability of extracted samples 

 The following section was written primarily for adsorbent media, but the same procedures can 

be used for filter media. Determine the extraction efficiency for support pads (if they are used 

with filters) as described in Step 9 of this Section. Determine the extraction efficiency for 

cassette wipes as described in Step 10 of this Section when sampling is performed using 25- or 

37-mm cassettes. If both filter and adsorbent media are used in the same sampler (e.g. OVS 

sampler), determine the extraction efficiency for each medium separately. 

 Determine extraction efficiency using only the front sections of two-section adsorbent tubes. It 

may be convenient to place the sampling medium in an extraction vial that has a septum cap 

and then spike it in the vial. 

 1. Determine the amount of time required to fully extract a constant amount of analyte 

from spiked samples. Extract and analyze a series of spiked samplers that covers the 

range of from the RQL to 2 times the target concentration for each sampler while 

increasing the amount of time between addition of the extraction solvent and analysis. 

Shake each sample by hand for a few seconds shortly after adding the solvent. If the 

extraction time is excessive, determine if mechanical agitation can reduce the time to 

fully extract the sample. SKC Passive Samplers are extracted using a specialized 

mechanical shaker. 

 2. The overall extraction efficiency is the mean percent of analyte recovered from dry 

samplers determined at 0.1, 0.25, 0.5, 1, 1.5, and 2 times the target concentration, 

based on the recommended air volume. If there are several target concentrations, 

select the target concentration and recommended sampling time combination which will 

produce the highest mass loading on the sampler. A dry sampler is one that is used as 

received from the manufacturer. The average of all the levels will be the overall 

extraction efficiency for the analytical procedure, provided they are similar. The 

average extraction efficiencies for each level tested should be within ±5% of the overall 

average. The individual extraction efficiencies within a level should agree to within 

±5%. If the extraction efficiency does not remain constant, determine if a different 

extraction solvent or extraction technique will provide constant results. If another 

extraction solvent does not provide constant results, a plot of extraction efficiency 

versus concentration shall be constructed and included in the method. Determine 

extraction efficiency at the RQL but do not include these results in the overall average. 

 Perform a test of the extraction efficiency with wet samplers but do not include the 

results in the overall average for dry samplers as follows: 

 a. Sample contaminant free humid air at an absolute humidity of 15.7 milligrams of 

water per liter of air (about 80% relative humidity at 22.2ΕC) at the recommended 

sampling rate for the recommended sampling time using four active samplers. 

Also expose four diffusive samplers to the humid air for the recommended 

sampling time. 

 

16 of 59 
 b. Spike the wet active and diffusive samplers at one times the target concentration. 

If there are several target concentrations, select the target concentration and 

recommended sampling time combination which will produce the highest mass 

loading on the sampler. 

 

 c. Extract and analyze the samples. If there is a significant difference in the mean of 

the extraction efficiency for wet samplers and the overall extraction recovery for dry 

samplers, repeat the test. A significant difference is when the mean of the wet 

samplers is 5 to 10% different from the mean of the dry sampler at the same mass 

loading. A difference of ≤5% is preferred. For GC analysis, the difference may be 

an analytical issue and it might be possible to resolve it by changing analytical 

method parameters such as the internal standard or the GC injector liner. If the 

difference persists, investigate changing the sampler or extraction solvent to 

minimize the difference. 

 d. An alternative, but less exact, way to simulate wet sampling media is to spike the 

medium with 50 μL of deionized water before spiking it with the analyte. 

 3. Prepare four samplers at each of the six concentrations. Prepare four samplers at the 

target concentration using wet media. Prepare an additional four samplers at the RQL. 

Store the spiked samples at room temperature for a sufficient time to assure complete 

adsorption of the analyte. Although the time required may vary with each particular 

analyte, the samples should be stored overnight unless a shorter time period can be 

justified. 

 4. Prepare three analytical standards at each of the six concentration levels. Prepare the 

analytical standards with the same microliter syringe used in spiking the extraction 

samples. 

 5. Extract the spiked samples using the selected technique. After an appropriate amount 

of time for equilibrium to occur, analyze the samples. Analyze standards and samples 

for each level in the following order: standard no. 1; samples no. 1 and no. 2; standard 

no. 2; samples no. 3 and no. 4; standard no. 3. Reseal two of the dry samples 

containing the target concentration amount of analyte immediately after analysis for use 

in the test described in Step 7 of this Section. 

 6. For each level, separately calculate the extraction efficiency for each of the spiked 

samples using the average of the three analytical standards as follows: 

 

where EE is extraction efficiency 100

M

M

E 

S

R (8) E = MR is mass recovered 

MS is mass spiked 

 Overall average extraction efficiency greater than 75% is acceptable but an average 

greater than 90% is preferred. 

 7. Determine the stability of extracted dry samples by reanalyzing the four dry target (2 

samples with resealed vials, and 2 samples with punctured septa) concentration 

extraction samples approximately 24, 48, and 72 hours after the extraction efficiency 

was initially determined. Reseal two of the four vials containing these samples with 

new septa after each analysis. The remaining two samples shall retain their punctured 

septa throughout the test. Use freshly prepared standards for each reanalysis. The 

results obtained from the resealed samples will determine if restrictions must be placed 

on how soon after extraction the samples must be analyzed. The results from the 

17 of 59 
samples stored with punctured septa will determine if restrictions must be placed on the 

reanalysis of samples that may sit (as in an autosampler tray) before reanalysis. 

Consider extracted samples stable for the length of time that the difference between 

results for the initial analysis and results for the reanalysis is not greater than 10% for 

each sample. Also determine the number of punctures in each septum during the 

injection of the sample and report this number. 

 8. If storage instability after 24 hours is detected in Step 7, a reduced time study may be 

necessary in which extracted samples are reanalyzed at sufficiently short time 

intervals. Use this data to determine how long after extraction a valid analysis (or 

reanalysis) can be performed. Use the same criteria for sample stability as above. 

 

 9. If support pads are used in conjunction with 25 or 37-mm filters, determine their 

extraction efficiency by spiking them with a sample loading equivalent to the RQL or 

0.05 times the target concentration whichever is higher. If a reactive reagent is used 

on the sampling filter it may be necessary to use the reagent in this test. 

 10. Select a medium and a technique (wet or dry) to be used to wipe interior walls of 25- or 

37-mm filter cassettes used for particulate sampling. Spike the interior walls of 4 

cassettes with 10 times the RQL or 0.1× target concentration (whichever is less), and 4 

separate cassettes with 1.0 times the target concentration of the analyte to determine 

the efficiency at which the analyte is removed by wiping. Allow these cassettes to 

stand for a sufficient time (overnight for nonvolatile analytes) and then use the selected 

technique to perform the test. Determine the extraction efficiency from the wipe 

medium by spiking the medium separately and allowing them to stand overnight. A 

minimum recovery of 75% is required for this test. If results are less than 75%, 

determine if a second wipe performed with the same wipe medium used to collect the 

first wipe sample and with the same spiked cassette used for that test will provide total 

results greater than 75%. Fold the wipe medium so that the first collected sample is 

inside the folded wipe to perform the second wipe. If the second wipe does not provide 

recovery greater than 75%, perform the second cassette wipe using a fresh wipe 

medium. If a reactive reagent is used on the sampling filter it may be necessary to use 

the reagent in this test. 

 

 D. Effects of storage 

 1. Ambient and refrigerated temperature storage tests are performed simultaneously if 

stability of the analyte on the collection medium is unknown or if recovery is expected 

to decrease over time. The refrigerated storage test is optional if the samples are 

stable at ambient temperature. Collect 33 samples if a refrigerated temperature test is 

performed or 18 samples if only an ambient test is performed, from a dynamically 

generated controlled test atmosphere containing the analyte at the target 

concentration. The absolute humidity should be 15.7 milligrams of water per liter of air 

(about 80% relative humidity at 22.2ΕC). Use the recommended sampling time; and 

the recommended sampling rate for active samplers. If sample collection is extremely 

time consuming, increase the test atmosphere concentration or increase the active 

sampling rate in order to obtain the correct analyte loading on the samplers within a 

reasonable time. If this approach is taken, make certain that sampler capacity is not 

exceeded due to the altered sampling conditions. 

 2. Analyze three samples on the day they are collected. Use the average diffusive 

sampling rate determined in Section III.B converted to its equivalent sampling rate at 

sampling site temperature and pressure to calculate results for diffusive samplers. Do 

not correct sample results for extraction efficiency. 

18 of 59 
 3. Store fifteen samples at ambient temperature in the dark, and store the remaining 15 

samples under refrigeration at a temperature of 2-6ΕC. 

 4. Analyze three samples from each set approximately every third day so that the storage 

test is at least two weeks in length. 

 5. Measure recovery from the regression curve obtained by plotting percent recovery (not 

corrected for extraction efficiency) versus days of storage. 

 6. A change in recovery of more than 10% in the two weeks is a significant uncorrectable 

bias and must be avoided. Also, the recovery (not corrected for extraction efficiency) 

must remain above 75% during storage and the 95% confidence limits must be within 

±25% (see Section IV.C). When these conditions are not met, they may be overcome 

by use of an alternate sampling medium, by refrigerated sample storage, or by time 

requirements placed on completion of the analysis. The preferable goal is the use a 

convenient sampler without restrictions on storage conditions, or time requirements for 

completion of analysis. The effect of ambient shipment to the laboratory and then 

refrigerated storage of samples until analysis can be estimated. This is done by 

tracking cumulative sample loss on the plot for the ambient storage test for the first five 

days and then switching to the plot for the reduced temperature test for the remainder 

of the storage time. If the change in recovery remains greater than 10%; or if recovery 

is still less than 75%; or if the 95% confidence limits are greater than ±25% even after 

sample refrigeration, an alternate sampling procedure must be found and tested. 

 7. Plot the storage test data as 

shown in Figure 6. Note that this 

figure includes data for the overall 

precision, which is defined in a 

following section. The scale on 

the vertical axis is from 0% to 

125%. The 95% confidence limits 

are ±1.96 times the overall 

standard error of estimate 

(equation 11) for the regression 

line for the storage data. 

0

25

50

75

100

125

0 5 10 15

{Analyte} Ambient Storage

y = 0.135x + 100.3

Overall Std Error of Estimate = 5.15%

95% Confidence Limits = ±(1.96)(5.15%) = ±10.1%

Storage Time (Days)

Recovery (%)

Figure 6. Example of a storage test. 

IV. Validation of Overall Procedure 

 A. Detection limit of the overall procedure 

(DLOP) 

 1. Determine DLOP using the same procedure that was used to determine DLAP (Section 

II.A), except data shall be obtained from spiked samplers instead of analytical 

standards. 

 2. Report the DLOP as mass per sample and as equivalent air concentrations based on 

the recommended sample air volume. 

 3. Prepare a plot of the DLOP data for inclusion in the method as shown in Figure 7. 

 

19 of 59 
 B. Reliable Quantitation Limit (RQL) 

 1. The RQL is the lower limit for precise quantitative measurements. Employing the 

regression line data used to calculate the DLOP, determine the RQL with the following 

formula, providing recovery from the sampler with mass closest to the RQL, is 100 

±25% of its theoretical value. 

A

S

10L Y X(DLOP)

RQL

⋅ (9) =

la. 

 

where LRQL is the reliable quantitation limit 

SY·X(DLOP) is the standard error of estimate for the 

regression line for DLOP 

A is the analytical sensitivity (slope) 

 If the recovery from the sampler with mass closest to the RQL is not within ±25% of its 

theoretical value, then the RQL will be equal to the lowest spiked concentration that is 

±25% of its theoretical value. Determine this from a plot of recovery versus mass as 

shown in Figure 8, for inclusion in the method. Additional data points can be obtained 

by spiking a series of samplers with 2, 3, 4, or 5 times the highest mass spiked for the 

DLOP. 

 2. Report the RQL as mass per sample and as an equivalent air concentration based on 

the recommended sample air volume. 

 3. Generate a chromatogram of the RQL for inclusion in the method. 

60

70

80

90

0 0.2 0.4 0.6 0.8 1.0

RQL

Mass (μg) per Sample

Recovery (%)

0

300

600

900

1200

1500

0 0.2 0.4 0.6 0.8 1.0

RQL

DLOP

Mass (μg) per Sample

Area Counts (μV•s)

Figure 7. Example of plotted DLOP/RQL data (y = 

1241x + 7.3).

Figure 8. Example of a calculated RQL when recovery 

is the determining factor (y = 33.5x + 62.3). 

 

 C. Determination of the precision 

 1. Use data from Effects of Storage (Section III.D) in the determination of the overall 

precision. The precision cited for the method is based on the storage data that reflects 

the temperature recommended for shipment of samples. 

 2. Determine the standard error of estimate for the regression curve5,6 of each storage 

test with the following formu

5

 Snedcor, G.W.; Cochran, W.G. Statistical Methods, 6th ed.; Iowa State University: Ames, Iowa, 1967; p 467. 6

 Arkin, H.; Colton, R. C. Statistical Methods, 5th ed.; Barnes & Noble: New York, 1970; pp 84-88. 

20 of 59 
 

where SY•X(STO) is the standard error of estimate from 

storage 

kn

)Y(Y S

2

OBS EST

X(STO)Y −

− = ∑ ⋅ (10) Yobs is observed response 

 Yest is estimated response from regression curve 

n is total number of data points 

k is 2 for a linear regression 

k is 3 for quadratic regression

 3. Determine the overall standard error of estimate for each sampler type from the data 

used in both storage tests. Use the ambient test if the restrictions in Section III.D.6. are 

satisfied. Use the overall standard error of estimate from the refrigerated storage test if 

the ambient test fails. If the refrigerated storage test also fails, restrictions must be set 

on the maximum storage time that will be allowed before samples must be analyzed. 

List the overall standard error of estimate on the cover page of the completed method. 

 a. Active sampler 

 Determine the overall standard error of estimate for the overall procedure for each 

storage test (SEE) by including the sampling pump variability (VSP) with the following 

formula. Use 5% for VSP. 

2 where SEE is the overall standard error of estimate 

SP

2 (11) EE = SS ⋅X(STO)Y +V SY·X(STO) is the standard error of estimate from 

storage 

VSP is the sampling pump variability (5%) 

 b. Diffusive sampler 

 Modification of the calculation for overall standard error of estimate is required for 

diffusive samplers because VSP is not an applicable parameter. In its place use 

sampling rate variation (VSR), which is considered a function of sampler design and 

must be determined before methods development work with the sampler is 

performed. Because diffusive sampling rates are a function of temperature (T) and 

atmospheric pressure (P), the standard error of estimate must include additional 

uncertainty when these parameters are not determined at the sampling site. (See 

Sections IV.C.7 and 8.) 

 The formula for the determination of the total standard error of estimate for diffusive 

samplers thus becomes: 

where SEE is the overall standard error of 

estimate 

2

P

2 (12) = ⋅ T +++ VV 2

SR

2

EE SS X(STO)Y V

SY·X(STO) is the standard error of estimate 

from storage 

 

VSR is the sampling rate variation

VT is the sampling rate uncertainty due 

to unreported temperature (7.7%)

VP is the sampling rate uncertainty due 

to unreported pressure (3%) 

 

21 of 59 
 but when the sampling site temperature and pressure are known, it simplifies to: 

 

2 where SEE is the overall standard error of estimate 

SR

2 (13) EE = SS ⋅X(STO)Y +V SY·X(STO) is the standard error of estimate from 

storage 

VSR is the sampling rate variation 

 The sampling rate variation must be determined for any manufacturer’s unique diffusive 

sampling product (such as 3M Organic Vapor Monitor, or SKC 575 Series Passive 

Sampler) before that sampler can be used by OSHA. Determine the sampling rate 

variation using a factorial test, similar to that of the NIOSH diffusive sampler testing 

protocol7

 or the SLTC protocol8,9 for the validation for diffusive samplers. The sampling 

rate variation for SKC 575 Series Passive Sampler and the 3M 3520 Organic Vapor 

Monitor was determined to be 8.7%10 and 6.4%11, respectively. 

 4. Assuming a normal distribution of values about the regression curve and uniformity of 

variation about the entire range of the storage stability curve, ±1.96 times the overall 

standard error of estimate will represent the 95% confidence limit which is the precision 

of the method. 

 5. Represent the overall precision data graphically as shown in Figure 6, and cite the 

overall standard error of estimate derived from the data that reflects the recommended 

temperature for sample shipment as the precision of the method. 

 6. The two-sided 95% confidence limits of the overall procedure must be within ∀25%. 

 7. When the temperature at the sampling site is unknown, a value of 7.7% is used for VT. 

This is an estimate of the maximum variation in sampling rate caused by a temperature 

range of 22.2 ∀ 15ΕC (72 ∀ 27ΕF). When the sampling site temperature is known, VT

is equal to zero. 

 

 8. When the pressure at the sampling site is unknown, determine it from the estimated 

elevation of the sampling site, and use a value of 3% for VP. This is the variation in 

pressure due to changing weather conditions, which was determined by tracking 

atmospheric pressure at SLTC for a year. When the pressure at the sampling site is 

known, VP is equal to zero. 

 

7

 Cassinielli, M.E.; Hull, R.D.; Crable, J.V.; and Teass, A.W., “Protocol for the Validation of Passive Monitors”, Diffusive Sampling: 

An Alternative Approach to Workplace Air Monitoring, Berlin, A.; Brown, R.H.; and Saunders, K.J., Eds., Royal Society of 

Chemistry, Burlington House, London, pp 190-202, 1987. 8

 Hendricks, W. Development of a Protocol for Laboratory Testing of Diffusive Samplers, 1996. United States Department of Labor, 

Occupational Safety & Health Administration web site. http://osha.gov/dts/sltc/methods/studies/3movm/3movm.html (accessed 

January 7, 2009). 9

 Hendricks, W. Determination of the Sampling Rate Variation for SKC 575 Series Passive Samplers, 1998. United States 

Department of Labor, Occupational Safety & Health Administration. 

http://osha.gov/dts/sltc/methods/studies/skc575/skc575.html (accessed January 7, 2009). 10 Hendricks, W. Determination of the Sampling Rate Variation for SKC 575 Series Passive Samplers, 1998. United States 

Department of Labor, Occupational Safety & Health Administration. 

http://osha.gov/dts/sltc/methods/studies/skc575/skc575.html (accessed January 7, 2009). 11 Hendricks, W. Development of a Protocol for Laboratory Testing of Diffusive Samplers, 1996. United States Department of 

Labor, Occupational Safety & Health Administration web site. http://osha.gov/dts/sltc/methods/studies/3movm/3movm.html 

(accessed January 7, 2009). 

22 of 59 
 9. If the elevation of the sampling 

site is unknown, the elevation can 

be estimated by data found on the 

internet. One internet source is: 

http://www.airnav.com. Select the 

AIRPORTS button. Select LOOK 

BY TOWN/REGION. Enter the 

city name. Check HELIPORTS 

and PRIVATE. This will identify all 

public airports, military airfields, 

private landing strips and all 

locations that accept helicopters. 

Select the radius of the search 

area. Select an airfield that is 

close to the sampling site. Maps 

are displayed to help with the 

selection of the nearest airfield. The elevation will be listed near the top of the airfield’s 

information. Use the equation in Figure 9 to estimate the atmospheric pressure of the 

sampling site. 

600

700

800

0 2000 4000 6000 8000

Elevation (ft)

Atmospheric Pressure (mmHg)

Figure 9. Plot of atmospheric pressure vs. elevation 

(y = 3.768E-07x2

 – 2.741E-02x + 760). 

Table 212

Atmospheric Pressure Versus Elevation 

elevation 

(ft) 

pressure 

(mmHg) 

elevation 

(ft) 

pressure 

(mmHg) 

elevation 

(ft) 

pressure 

(mmHg) 

elevation 

(ft) 

pressure 

(mmHg) 

elevation 

(ft) 

pressure 

(mmHg) 

0 

100 

200 

300 

400 

500 

600 

700 

800 

900 

760 

757 

755 

752 

749 

746 

744 

741 

738 

736 

1000 

1100 

1200 

1300 

1400 

1500 

1600 

1700 

1800 

1900 

733 

730 

727 

725 

722 

720 

717 

714 

712 

709 

2000 

2100 

2200 

2300 

2400 

2500 

2600 

2700 

2800 

2900 

707 

704 

701 

699 

696 

694 

691 

689 

686 

683 

3000 

3200 

3400 

3600 

3800 

4000 

4200 

4400 

4600 

4800 

681 

676 

671 

667 

661 

657 

651 

647 

642 

637 

5000 

5200 

5400 

5600 

5800 

6000 

6500 

7000 

7500 

8000 

632 

628 

623 

619 

613 

609 

597 

587 

575 

565 

 D. Reproducibility 

 1. Prepare six samples for each target concentration and for each sampler type in the 

same manner as used to prepare storage samples. Submit them to SLTC for analysis. 

Include a complete draft copy of the method for analyst instruction. The analyst will 

analyze the samples relying solely on the draft method for guidance to reproduce the 

analytical conditions. If possible, the analyst will use different analytical equipment to 

analyze the samples than was used to develop the method. If the samples are stored 

before analysis, the conditions under which they are stored should correspond to the 

recommended storage conditions of the method. If the analyte has a ceiling, peak or 

short term exposure limit, generate another set of reproducibility samples if the mass of 

analyte for the short-term sample is less than 10% of the mass collected for a long-term 

sample. 

 

12 Nelson, G.O., Gas Mixtures Preparation and Control, Lewis Publishers, Boca Raton, 1992, p. 265-266. 

23 of 59 
 2. No individual analytical result shall deviate from the theoretical value by more than 1.96 

times the standard error of estimate determined in Section IV.C. If this does occur, 

steps must be taken to determine and eliminate the cause of the excessive imprecision 

(e.g., an unanticipated technical problem or a lack of clarity in the analytical instructions 

provided in the draft copy). The analyst will discuss any problem or concern that arises 

from analysis of the reproducibility samples with the person that developed the method. 

The reproducibility test must then be repeated. 

 3. The analyst will discuss the analysis of the reproducibility samples with the Methods 

Development Team supervisor or team leader. 

24 of 59 
PREPARATION OF WRITTEN REPORTS FOR FULLY VALIDATED METHODS

The following format provides a means of reporting data obtained during validation of sampling and 

analytical methods that employ chromatographic analysis. The cover page is intended as a quick 

reference that provides basic information. The Method Validation Section contains tabulated and 

graphical laboratory data that may be referenced throughout the report. 

Each fully validated method will be assigned a version number beginning with the number "1.0". 

Significant changes or revisions to the method require that a new version number be assigned, for 

example "2.0". If the document is revised, the date revised will be placed on the cover page and a 

discussion concerning the revision included in Section 1.1.1 History. 

Required statements concerning the status of the method, accessibility problems, intended use of the 

method, manufacturer disclaimer, toxic effects disclaimer, reference to OSHA Methods Development 

Guidelines, basis of cited air concentrations, sampling safety, chemical hygiene plan, analytical safety, 

and QA practices are placed at certain points in the method text. These required statements will not be 

altered and will be inserted in the locations shown in the example fully validated method. 

Text formatting, instructions for field and laboratory personnel, and descriptive discussion shown in the 

example fully validated method will not be altered unless such text in clearly inaccurate or inappropriate. 

The purpose of section and paragraph indents is to delineate text and to provide a convenient way to 

reference sections and paragraphs in subsequent sections and paragraphs. Indents should be used as 

shown in the example fully validated method unless additional indents are necessary for clarity. 

Quaternary indents , for example 3.4.1.1, will be avoided whenever possible. 

Page Numbering - Number the cover page. Number pages in the center of the footer in 8 point Arial font. 

Example: The first page of Method 1001 would be "1 of 38". 

Editorial comments and text locations requiring the author to insert information are set off with braces 

"{ }". The note in braces is not itself intended to be inserted in the method. 

Text will be written in 10 point Arial font with full justification with no added hyphenation. 

Tabs: Cover page - 2.0 - Method - 0.25, 0.63, 1.13, 1.38 

OSHA logo on cover page - size = 0.500", right margin, wrap behind text. 

Graphs - size = 3.1", caption is 9 point Arial font. 

Tables- size = 3.1, 9 point Arial font. 

References will follow as closely as possible the format recommended by the American Chemical Society 

in the 3rd edition of "The ACS Style Guide - A Manual for Authors and Editors." 

25 of 59 
{ANALYTE} 

{as listed in CFR or ACGIH} 

Method number: 1xxx 

Version: x.0 

Target concentration: ____ ppm (____ mg/m3

) 

OSHA PEL: ____ ppm (____ mg/m3

) {None if no PEL} 

ACGIH TLV: ____ ppm (____ mg/m3

) {None if no TLV} 

{Include skin designations when applicable} 

Procedure: Active samples are collected by drawing workplace air through ____ 

{active sampler} with personal sampling pumps. Diffusive samples are 

collected by exposing ____ {diffusive sampler} to workplace air. 

Samples are extracted with ____ and analyzed by ____ using a ____ 

detector. 

Recommended sampling time 

and sampling rate: 

____ {Active sampler}: ____ min at ____ mL/min (____ L) 

{If the sampling rate is 

greater than 250 mL/min, 

use L/min} 

____ {Diffusive sampler}: ____ min (sampling rate at 760 mmHg and 25 °C ____ mL/min) 

Reliable quantitation limit: 

____ {Active sampler}: ____ ppm (____ mg/m3

) 

____ {Diffusive sampler}: ____ ppm (____ mg/m3

) 

Standard error of estimate 

at the target concentration: 

____ {Active sampler}: ____% 

____ {Diffusive sampler}: ____%* 

*For diffusive samplers when sampling site atmospheric pressure and 

temperature are known. When either or both of these values are 

unknown, see Section 4.5 for applicable standard errors of estimate. 

Special requirements: When using a ____ {diffusive sampler}, report the temperature and 

uncorrected sampling site atmospheric pressure. {If there are no special 

requirements, delete this item} 

Status of method: Fully validated method. This method has been subjected to the 

established validation procedures of the Methods Development Team. 

____ {month year} {Chemist} ____ 

Date revised ____ {month year} 

Methods Development Team 

Industrial Hygiene Chemistry Division 

OSHA Salt Lake Technical Center 

Sandy UT 84070-6406 

26 of 59 
1. General Discussion 

 For assistance with accessibility problems in using figures and illustrations presented in this method, 

please contact the Salt Lake Technical Center (SLTC) at (801) 233-4900. This procedure was 

designed and tested for internal use by OSHA personnel. Mention of any company name or 

commercial product does not constitute endorsement by OSHA. 

 1.1 Background 

 1.1.1 History 

{Explain why past methodology is inadequate, and how the new procedure is superior. 

Also, obvious questions that may be raised by knowledgeable readers should be 

addressed. Keep length to 1.5 pages or less.} 

 1.1.2 Toxic effects (This section is for information only and should not be taken as the basis 

of OSHA policy.) 

{Cite sources for presented information. If both animal data and human data are 

presented, present the animal data first. If the entire section is taken from one 

reference, the reference notation can be placed behind the qualifying statement in the 

heading.} 

 1.1.3 Workplace exposure 

{Report major sources of exposure in the workplace and, if available, the size of the 

work population that is exposed. If the entire section is taken from one reference, the 

reference notation can be placed behind the heading.} 

 1.1.4 Physical properties and descriptive information {these are examples and can be used if 

applicable, other physical properties can also be listed.} 

 synonyms: ____ 

 solubility: ____ 

 IMIS number13: ____ appearance: ____ 

 CAS number: ____ vapor pressure: {kPa (mmHg)} ____ 

 molecular weight: ____ flash point: ____ 

 boiling point: ____ odor: ____ 

 melting point: ____ lower explosive limit: ____ 

 8max: ____ specific gravity: ____ 

 structural formula: ____ molecular formula: ____ 

 

13 Chemical Sampling Information. U.S. Department of Labor, Occupational Safety and Health Administration Web site. 

http://osha.gov/dts/chemicalsampling/toc/toc_chemsamp.html (accessed March 11, 2009). 

27 of 59 
This method was validated according to the OSHA SLTC “Validation Guidelines for Air Sampling Methods 

Utilizing Chromatographic Analysis”14. The Guidelines define analytical parameters, specify required 

laboratory tests, statistical calculations, and acceptance criteria. The analyte air concentrations 

throughout this method are based on the recommended sampling and analytical parameters. Air 

concentrations listed in ppm are referenced to 25ΕC and 760 mmHg (101.3 kPa). 

2. Sampling Procedure 

 All safety practices that apply to the work area being sampled should be followed. The sampling 

equipment should be attached to the worker in a manner that will not interfere with work performance 

or safety. 

 

 2.1 Apparatus {Provide general descriptions of the required equipment followed by a description of 

specific equipment actually used in the validation, if applicable.} 

 2.1.1 ____ {Active sampler} 

 Example: 

Samples are collected with {description of the sampler, 7-cm Η 4-mm i.d. Η 6-mm o.d. 

glass sampling tubes packed with two sections of ____ {adsorbent}}. The front section 

contains 110 mg and the back section contains 55 mg of ____ {adsorbent}. The 

sections are held in place and separated with glass wool plugs. For this validation, 

commercially prepared ____ {active samplers} were purchased from ____ {Supplier} 

(catalog no. ____, lot no._____). 

A sampling tube holder is required to protect the worker from the sharp end of the glass 

sampling tube. 

Samples are collected using a personal sampling pump calibrated to within ∀5% of the 

recommended flow rate with the sampling device in-line. 

 2.1.2 ____ {Diffusive sampler} 

Samples are collected with a ____ {diffusive sampler}. For this validation, 

commercially available samplers were purchased from ____ {Supplier} (catalog no. 

_____, lot no. _____). 

 2.1.3 A thermometer and barometer are required to determine the sampling site air 

temperature and atmospheric pressure. 

 2.2 Reagents {If no reagents are required, state "None required". Otherwise use the format 

described in Section 3.2.} 

 2.3 Technique {Describe steps involved in sample collection, preparation, and shipment.} 

 

 2.3.1 ____ {Adsorbent tube} 

 

14 Eide, M.; Simmons, M.; Hendricks, W. Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis, 2010. 

United States Department of Labor, Occupational Safety & Health Administration. 

http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf (accessed March 11, 2010).

28 of 59 
Immediately before sampling, break off the ends of the flame-sealed tube to provide an 

opening approximately half the internal diameter of the tube. Wear eye protection 

when breaking ends. Use sampling tube holders to minimize the hazard to the worker 

from the broken ends of the tubes. All tubes should be from the same lot. 

The smaller section of adsorbent in the adsorbent tube is used as a back-up and is 

positioned nearest the sampling pump. Attach the tube holder (with the adsorbent 

tube) to the sampling pump so that the adsorbent tube is in an approximately vertical 

position with the inlet facing down in the worker’s breathing zone during sampling. 

Position the sampling pump, tube holder, and tubing so they do not impede work 

performance or safety. 

Draw air directly into the inlet of the sampling tube holder. The air being sampled 

should not pass through any hose or tubing before entering the sampling tube. 

Sample for up to ____ min at ____ mL/min (____ L) when using ____ {sampler} to 

collect TWA (long-term) samples. 

Sample for ____ min at ____ mL/min (____ L) when using ____ {sampler} to collect 

{short-term, ceiling, or peak whichever is appropriate} samples. 

After sampling for the appropriate time, remove the adsorbent tube and seal it with 

plastic end caps. Seal each sample end-to-end with a Form OSHA-21 as soon as 

possible. 

Submit at least one blank sample with each set of samples. Handle the blank sample 

in the same manner as the other samples except draw no air through it. 

Record sample air volume (liters), sampling time (min) and sampling rate (mL/min) for 

each sample, along with any potential interference on the Form OSHA-91A. 

Submit the samples to the laboratory for analysis as soon as possible after sampling. If 

delay is unavoidable, store the samples in a refrigerator as a precaution. 

Ship any bulk sample(s) separate from the air samples. 

 

 2.3.2 ____ {Filter sampler} 

Remove the plastic end plugs from the filter cassette immediately before sampling. 

{Remove the rear plastic plug and the top piece of the filter cassette for open-face 

sampling.} 

Attach the cassette to the sampling pump so that it is in an approximately vertical 

position with the inlet facing down during sampling. Position the sampling pump, 

cassette, and tubing so it does not impede work performance or safety. 

Draw the air to be sampled directly into the inlet of the cassette. The air being sampled 

is not to be passed through any hose or tubing before entering the cassette. 

Sample for up to ____ min at ____ L/min (____ L) when using ____ {sampler} to collect 

TWA (long-term) samples. 

Sample for ____ min at ____ L/min (____ L) when using ____ {sampler} to collect 

{short-term, ceiling, or peak whichever is appropriate} samples. 

29 of 59 
After sampling for the appropriate time, remove the sample and seal the cassette with 

plastic end plugs {plug and top piece}. Seal each sample end-to-end with a Form 

OSHA-21 as soon as possible. 

Submit at least one blank sample with each set of samples. Handle the blank sampler 

in the same manner as the other samples except draw no air through it. 

Record sample air volumes (liters), sampling time (min), and sampling rate (L/min) for 

each sample, along with any potential interference. 

Submit the samples to the laboratory for analysis as soon as possible after sampling. 

If delay is unavoidable, store the samples in a refrigerator as a precaution. 

Ship any bulk sample(s) separate from the air samples. 

 2.3.3 SKC 575-002 Passive Samplers (In general, follow the manufacturer's instructions.) 

 Remove the sampler from its air-tight package. 

Record the start time on the sampler label and on the Form OSHA-91A. Remove the 

cover and cover retainer when ready to begin sampling. CAUTION - The sampler 

immediately begins to sample when the cover is removed. Keep the O-ring, press-on 

cover, cover retainer, port plugs and poly(tetrafluorethylene) (PTFE) tube in the 

package for later use. 

Attach the sampler to the worker near his/her breathing zone with the perforations in 

the sampler facing forward. Assure that the area directly in front of the sampler is 

unobstructed throughout the sampling period. 

Sample for up to ____ min when using ____ {sampler} to collect TWA (long-term) 

samples. The sampling rate for ____ {analyte} using ____ {sampler} is ____ mL/min at 

760 mmHg and 25 °C. 

Sample for ____ min when using ____ {sampler} to collect {short-term, ceiling, or peak 

whichever is appropriate} samples. The sampling rate for ____ {analyte} using ____ 

{sampler} is ____ mL/min at 760 mmHg and 25 °C. 

At the end of the sampling period, immediately detach the sampler from the worker and 

attach the O-ring and cover onto the side of the sampler with the perforations. Secure 

the cover onto the sampler using the cover retainer. Visually inspect the O-ring to be 

sure it is forming a proper seal around the entire circumference of the sampler. Record 

the stop time on the sampler label and also on the Form OSHA-91A. Return each 

sampler to its package, close the package, and seal it with a Form OSHA-21. 

Prepare a blank in a low background area by removing an unused sampler from its 

package. Then remove the cover and the cover retainer. Immediately attach an Oring, a cover, and a cover retainer onto the sampler. Return the blank sampler to its 

package, close the package, and seal it with a Form OSHA-21. 

Verify that the sampling times are properly recorded on the Form OSHA-91A for each 

sample. Also, identify blank samples on this form. 

Record the room temperature and atmospheric pressure at the sampling site on the 

Form OSHA-91A. 

30 of 59 
List any compounds that could be considered potential interferences, especially 

solvents that are being used in the sampling area. 

Submit the samplers to the laboratory for analysis as soon as possible. Include all port 

plugs and PTFE tubes which will be used in the laboratory analyses in the bag with the 

sampler. If delay is unavoidable, store the samples in a refrigerator as a precaution. 

 Ship any bulk sample(s) in a container separate from the air samples. 

 2.3.4 3M 3520 OVMs (In general, follow the manufacture’s instructions.) 

The samplers come individually sealed in small metal cans. When ready to begin 

sampling, remove the plastic lid from the can and lift up on the revealed ring. Pull back 

on the ring to open the can. Discard the metal top of the can and remove the sampler. 

CAUTION - The sampler immediately begins to sample when the can is unsealed. 

Keep the two closure caps with attached port plugs, cup and PTFE tubes in the can for 

later use. Close the can with the plastic lid. 

Record the start time on the back of the sampler and on the Form OSHA-91A. 

Attach the sampler to the worker near his/her breathing zone with the white face 

forward. Assure that the area directly in front of the sampler is unobstructed throughout 

the sampling period. Do not remove the white film and ring from the sampler until the 

sampling period is terminated. 

Sample for up to ____ min when using ____ {sampler} to collect TWA (long-term) 

samples. The sampling rate for ____ {analyte} using ____ {sampler} is ____ mL/min at 

760 mmHg and 25 °C. 

Sample for ____ min when using ____ {sampler} to collect {short-term, ceiling, or peak 

whichever is appropriate} samples. The sampling rate for ____ {analyte} using ____ 

{sampler} is ____ mL/min at 760 mmHg and 25 °C. 

At the end of the sampling period, detach the sampler from the worker and remove the 

white film and retaining ring. For each sampler (one sampler at a time), immediately

after removing the white film and retaining ring, separate the primary (top), and 

secondary (bottom) sections of the sampler using the edge of a coin as a pry. Snap a 

closure cap onto the top of the primary section. Snap a cup onto the bottom of the 

primary section. Snap a closure cap onto the secondary section of the sampler. 

Assure that the attached port plugs are all placed firmly into the port holes. Return the 

sampler sections (with their closure caps, cup, and port plugs all securely affixed) to the 

metal can which contains the PTFE tubes (which will be used by the laboratory). Close 

the can with the plastic lid, and seal it with a Form OSHA-21. 

Perform the following in a low background area for a set of samplers as soon as 

possible after sampling. Prepare a blank by removing the white film and ring and 

attaching a closure cap onto an unused sampler. For the blank sampler, separate the 

primary (top), and secondary (bottom) sections of the sampler using the edge of a coin 

as a pry. Snap a cup onto the bottom of the primary section. Snap a closure cap onto 

the secondary section of the sampler. Assure that the attached port plugs are all 

placed firmly into the port holes. Return the blank sampler sections (with their closure 

caps, cup, and port plugs all securely affixed) to the metal can which contains the 

PTFE tubes (which will be used by the laboratory). Close the can with the plastic lid, 

and seal it with a Form OSHA-21. 

31 of 59 
 Verify that the sampling times are properly recorded on the Form OSHA-91A for each 

sample. Also, identify blank samples on this form. 

 Record the room temperature and atmospheric pressure of the sampling site on Form 

OSHA-91A. 

 List any compounds that could be considered potential interferences, especially 

solvents that are being used in the sampling area. 

 Submit the samplers to the laboratory for analysis as soon as possible. If delay is 

unavoidable, store the samples in a refrigerator as a precaution. 

 Ship any bulk sample(s) in a container separate from the air samples. 

3. Analytical Procedure 

Adhere to the rules set down in your laboratory's Chemical Hygiene Plan15 (for instance: OSHA SLTC 

adheres to the rules set down in the OSHA SLTC Chemical Hygiene Plan). Avoid skin contact and 

inhalation of all chemicals and review all appropriate MSDSs before beginning the analytical 

procedure. Follow all applicable quality assurance practices established in your laboratory's internal 

quality system (for instance: OSHA SLTC follows the quality assurance practices established in the 

OSHA SLTC Quality Assurance Manual). 

 

 3.1 Apparatus {Provide general descriptions of the required equipment. Follow each general 

description with a specific description of equipment actually used in the validation.} 

 Example: 

 Gas chromatograph equipped with an FID. An Agilent 6890 Series GC System was used in 

this validation. 

 3.2 Reagents {Provide general descriptions of the required reagents. Follow each general 

description with a description of the specific reagent actually used in the validation.} 

 Example: 

 Methylene chloride, [CAS no.], ___ grade or better. The methylene chloride used in this 

validation was A.C.S. HPLC grade (lot no. Q87C654) purchased from Aldrich (Milwaukee, WI). 

 Carbon disulfide (CS2), [CAS no.], ____ grade or better. The CS2 used in this validation was 

low benzene grade (lot no. 37529) purchased from JT Baker Chemical Co. (Phillipsburg, NJ). 

N,N-Dimethylformamide (DMF), [CAS no.], ____ grade or better. The DMF used in this 

validation was 99+% (lot no. LP642) purchased from Aldrich (Milwaukee, WI). 

p-Cymene, [CAS no.], The p-cymene used in this validation was 99+% (lot no. SW 9180SU) 

purchased from Aldrich (Milwaukee, WI). 

 Extraction solvent. The extraction solvent used in this validation consisted of ____ {list volume} 

μL/mL p-cymene in 99/1 (V/V) CS2/DMF. The p-cymene was added as an internal standard. 

The extraction efficiency is affected by the extraction solvent, the internal standard, the 

sampling medium, and the technique used to extract the samples. Other reagents and 

techniques than described in this method can be used provided they are tested as specified in 

the validation guidelines.16 

 

15 Occupational Exposure to Hazardous Chemicals in Laboratories. Code of Federal Regulations, Part 1910.1450, Title 29, 2003. 16 Eide, M.; Simmons, M.; Hendricks, W. Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis, 2010. 

United States Department of Labor, Occupational Safety & Health Administration. 

http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf (accessed March 11, 2010).

32 of 59 
 3.3 Standard preparation {Describe preparation of standards in general and give an example.} 

 Example: 

 Prepare concentrated stock standards of ____ {analyte} in the extraction solvent. Prepare 

working analytical standards by injecting microliter amounts of concentrated stock standards 

into 2-mL vials containing 1 mL of extraction solvent delivered from the same dispenser used to 

extract samples. For example, to prepare a target level standard, inject ____ μL of a stock 

solution containing ____ mg/mL of ____ {analyte} into 1 mL of extraction solvent. 

 Bracket sample concentrations with standard concentrations. If upon analysis, sample 

concentrations fall outside the range of prepared standards, prepare and analyze additional 

standards to confirm instrument response, or dilute high samples with extraction solvent and 

reanalyze the diluted samples. 

 3.4 Sample preparation {Describe steps involved in preparing samples for analysis.} 

 

 Example: 

 3.4.1 ____ {Active sampler} 

Remove the plastic end caps from the sample tube and carefully transfer each section 

of the adsorbent to separate 2-mL vials. Discard the glass tube and glass wool plugs. 

Add 1.0 mL of extraction solution to each vial and immediately seal the vials with 

PTFE-lined caps. 

Extract the samples for ____ {30 min} by {describe technique}. 

 3.4.2 SKC 575-002 Samplers (In general, follow the manufacturer's instructions.) 

Cut off the ends of the two protruding tubes of each sampler with a razor blade, sharp 

knife, or scissors. 

Slowly add 1.0 mL of extraction solvent through one of the protruding tubes (ports). 

After about 30 seconds, slowly add another 1.0 mL of extraction solvent. 

Immediately insert plugs into the ports. 

Mount the samplers on the sampler rack (SKC Cat. No. 226-04-5) of a specialized 

shaker (SKC Cat. No. 226D-03-1) and shake the samplers for ____ {time}. 

Do not leave the extracted sample in the sampler. Transfer each extracted sample by 

removing the plugs from the sampler ports, firmly inserting the tapered end of a 

supplied PTFE tube into the outer port and carefully pouring the solution through the 

PTFE tube into a labeled autosampler vial. 

 3.4.3 3M 3520 OVMs (In general, follow the manufacturer's instructions.) 

Remove both sampler sections from the metal cans, along with the sections of PTFE 

tubing. Assure that the closure caps are firmly snapped to the primary and secondary 

sections of all the samplers. Also assure that all cap plugs are firmly seated in the cap 

ports. Any deviations must be noted. 

Prepare one section of the sampler at a time by temporarily removing the cap plugs 

from the ports and adding 2.0 mL of extraction solvent through the center port. This is 

most easily done by dispensing two 1.0-mL aliquots of extraction solvent using a 

dispenser. Immediately replace the plugs in the ports. {An alternate means of 

33 of 59 
preparation for 3M 3520 OVMs is to remove the cap, remove the interior retaining ring, 

remove the front charcoal pad, and place it into a 4-mL vial. Remove the pad from the 

second section of the sampler in similar fashion and place it in a separate 4-mL vial. 

Add 2-mL of the extraction solvent to each vial and cap the vials.} Extract the sample 

for ____ {min} by {describe technique}. 

Transfer the solution from each sampler section by removing both plugs from the ports, 

inserting a supplied decanting spout (a small section of PTFE tubing) into the outer port 

and pouring the liquid through the spout into a labeled autosampler vial. {or by 

transferring the solution from the extraction vial to a labeled autorampler vial}. 

Immediately cap each vial. 

 

 3.5 Analysis 

 {Provide detailed instrument settings; include a chromatogram at the target concentration, a 

calibration curve, and the calibration technique used.} 

 3.5.1 Analytical conditions 

 Example: 

GC conditions

oven temperature: 60 °C (hold 1 min), ramp to 225 °C at 15 °C/min (hold 3 min) 

injector temperature: 250 °C 

detector temperature: 300 °C 

run time: 15 min 

column: Supelco SPB-5 capillary column, 60-m × 0.32-mm i.d, df = 1.0-

μm, or equivalent 

column mode: constant pressure (14 psi) {or constant flow} 

initial column gas flow: 1.2 mL/min (hydrogen) 

septum purge: 1.5 mL/min (hydrogen) 

injection size: 1.0 μL (10 to 1 split) 

inlet liner: Agilent 5183-4647 or equivalent 

retention times: 6.5 min (compound A) 

6.9 min (compound B) 

10.0 min (compound C) 

13.6 min (compound D) 

FID conditions

hydrogen flow: 30 mL/min 

air flow: 450 mL/min 

nitrogen make up flow: 45 mL/min 

34 of 59 
0

50

100

150

200

250

0 5 10 15

4 3 1 2

Time (min)

Response (m

V)

Figure 3.5.1. Chromatogram obtained at the target

concentration with the recommended analytical

conditions (1: compound A; 2: compound B; 3:

compound C; 4: compound D). 

 

 3.5.2 An internal standard (ISTD) calibration method is used. A calibration curve can be 

constructed by plotting ISTD-corrected response of standard injections versus 

micrograms of analyte per sample. Bracket the samples with freshly prepared 

analytical standards over a range of concentrations. 

0

0.2x105

0.4x105

0.6x105

0.8x105

1.0x105

0 500 1000 1500 2000 2500

Mass (μg) per Sample

Area Counts (μV•s)

Figure 3.5.2. Calibration curve for ____ {analyte} (y = 

38.89x -65.50).

 3.6 Interferences (analytical) 

 Example: 

 3.6.1 Any compound that produces an FID response and has a similar retention time as the 

analyte or internal standard is a potential interference. If any potential interferences 

were reported, they should be considered before samples are extracted. Generally, 

chromatographic conditions can be altered to separate interferences from the analyte. 

35 of 59 
 3.6.2 When necessary, the identity of an analyte peak can be confirmed with additional 

analytical data or procedures (Section 4.10). 

 3.7 Calculations {Use 24.46 L/mole [(22.41 L/mole)(298.2 K)/273.2 K] for the molar volume.} 

 Example: 

 3.7.1 ____ {Active sampler} 

The amount of ____ {analyte} per sample is obtained from the appropriate calibration 

curve in terms of micrograms per sample, uncorrected for extraction efficiency. The 

back section is analyzed primarily to determine the extent of sampler saturation. If any 

analyte is found on the back section, it is added to the amount on the front section. If 

more than 20% of the total amount is found on the back section, report that the sampler 

may have been saturated on the Form OSHA-91B. This total amount is then corrected 

by subtracting the total amount (if any) found on the blank. The air concentration is 

calculated using the following formulas. 

 

where CM is concn by weight in air (mg/m3) 

M is micrograms per sample 

E V is liters of air sampled 

M VE

M C =

EE is extraction efficiency, in decimal form 

where CV is concn by volume (ppm) 

CM is concn by weight in air (mg/m3

) 

VM is 24.46 (molar volume at NTP) r

MM

V M

VC C =

Mr is molecular weight 

 

 3.7.2 ____ {Diffusive sampler} 

The amount of ____ {analyte} for the samples is obtained from the appropriate 

calibration curve in terms of micrograms per sample, uncorrected for extraction 

efficiency. The back section of a 3M 3520 OVM is analyzed primarily to determine the 

extent of sampler saturation. If any analyte is found on the back section, this amount is 

multiplied by 2.2 (as per manufacturer’s instructions) and then added to the amount on 

the front section. If more than 20% of the total amount is found on the back section, 

report that the sampler may have been saturated on the Form OSHA-91B. This total 

amount is then corrected by subtracting the total amount (if any) found on the blank. 

The air concentration is calculated using the following formulas. 

 

where RSS is the sampling rate at the sampling site 

(mL/min) 

RNTP is the sampling rate at NTP (mL/min) 

TSS is the temp at the sampling site (K) 

TNTP is 298.2 K 

PSS is the sampling site pressure (mmHg) 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ =

SS

NTP 2

3

NTP

SS

SS NTP P

P

T

T RR

PNTP is 760 mmHg 

 

where CM is concn by weight in air (mg/m3) 

M is micrograms per sample 

RSS is the sampling rate at the sampling site 

(mL/min) 

t is the sampling time (min) 

ESS

M E t R

1000M C =

EE is extraction efficiency in decimal form 

 

where CV is concentration by volume (ppm)

VM is 24.46 (molar volume at NTP)

CM is concentration by weight (mg/m3

) r

MM

V M

VC C =

Mr is molecular weight

 

36 of 59 
If the sampling site temperature is not provided, assume that it is 22.2ΕC. If the 

sampling site atmospheric pressure is not given, calculate an approximate value based 

on the sampling site elevation from the following equation. 

 

Pss is the approximate atmospheric pressure 

(mmHg)

E is the sampling site elevation (ft) 

A is 3.768 × 10-7 mmHg/ft2

760BEAEP 2

SS +−=

B is 0.02741 mmHg/ft 

4. Method Validation 

General instruction for the laboratory validation of OSHA sampling and analytical methods that employ 

chromatographic analysis is presented in “Validation Guidelines for Air Sampling Methods Utilizing 

Chromatographic Analysis”17. These Guidelines detail required validation tests, show examples of 

statistical calculations, list validation acceptance criteria, and define analytical parameters. Air 

concentrations listed in ppm are referenced to 25 °C and 760 mmHg (101.3 kPa). 

 

 4.1 Detection limit of the analytical procedure (DLAP) {Present test data in a table and in a graph. 

{Use a single summary paragraph, and separate tables and graphs for multiple analytes.} 

 Example: 

 The DLAP is measured as the mass of analyte introduced onto the chromatographic column. 

Ten analytical standards were prepared with equally descending increments of ____ {analyte} 

with the highest standard containing ____ μg/mL. This is the concentration that would produce 

a peak approximately 10 times the response of a reagent blank at or near the chromatographic 

retention time of the analyte. These standards and the reagent blank were analyzed with the 

recommended analytical parameters (1-μL injection with a __:1 split). The data obtained were 

used to determine the required parameters (standard error of estimate and slope) for the 

calculation of the DLAP. Values of ____ and ____ were obtained for the slope and standard 

error of estimate respectively. The DLAP was calculated to be ____ pg. 

 

0

500

1000

1500

0 150 300 450

DLAP

Mass (pg) Injected Onto Column

Area Counts (μV•s)

Figure 4.1. Plot of data to determine the DLAP (y = 3.28x 

+ 20.8). 

 4.2 Detection limit of the overall procedure (DLOP) and reliable quantitation limit (RQL) {Present 

test data in a table, in a graph, and in a chromatogram of the RQL. Use a single summary 

Table 4.1 

Detection Limit of the Analytical Procedure 

concentration 

(μg/mL) 

mass on column area counts 

(pg) (μV-s) 

0 0 0 

0.421 42.1 173 

0.841 84.1 318 

1.26 126 425 

1.68 168 573 

2.10 210 690 

2.52 252 853 

2.94 294 973 

3.36 336 1150 

3.78 378 1270 

4.21 421 1380 

 

17 Eide, M.; Simmons, M.; Hendricks, W. Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis, 2010. 

United States Department of Labor, Occupational Safety & Health Administration. 

http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf (accessed March 11, 2010).

37 of 59 
paragraph and separate tables and chromatograms for multiple analytes and samplers. 

Present DLOP and RQL values in separate summary tables if there are multiple analytes or 

samplers} 

 

The DLOP is measured as mass per sample and expressed as equivalent air concentrations 

based on the recommended sampling parameters. Ten samplers were spiked with equally 

descending increments of analyte, such that the highest sampler loading was ____ μg/sample. 

This is the amount spiked on a sampler that would produce a peak approximately 10 times the 

response of a sample blank at or near the chromatographic retention time of the analyte. These 

spiked samplers and the sample blank were analyzed with the recommended analytical 

parameters, and the data obtained used to calculate the required parameters (standard error of 

estimate and the slope) for the calculation of the DLOP. Values of ____ and ____ were 

obtained for the slope and standard error of estimate respectively. The DLOP was calculated to 

be ____ μg/sample (____ ppm or ____ mg/m3

). 

0

300

600

900

1200

1500

0 0.2 0.4 0.6 0.8 1.0

RQL

DLOP

Mass (μg) per Sample

Area Counts (μV•s)

Table 4.2 

Detection Limit of the Overall Procedure 

mass per sample 

(μg) 

area counts 

(μV-s) 

0 

0.096 

0.191 

0.287 

0.232 

0.478 

0.573 

0.669 

0.764 

0.860 

0.955 

0 

118 

214 

357 

515 

623 

744 

916 

864 

1043 

1208 

Figure 4.2.1. Plot of data to determine the 

DLOP/RQL (y = 277x – 75.5).

The RQL is considered the lower limit for 

precise quantitative measurements. It is 

determined from the regression line 

parameters that were obtained for the 

calculation of DLOP providing 75% to 

125% of the analyte is recovered. The 

RQL is ____ μg/sample (____ ppm or ____ 

μg/m3

). Recovery at this concentration is 

____%. 

When short-term samples are collected, 

the air concentration equivalent to the 

reliable quantitation limit becomes larger. 

For example, the reliable quantitation limit 

for ____ {active sampler} is ____ ppm 

(____ mg/m3

) for ____ {analyte} when 

____ L is sampled. 

 4.3 Precision of the analytical method 

 Example: 

 The precision of the analytical method measured as the mass equivalent to the standard error 

of estimate determined from the {list type of curve, example: linear} regression of data points 

from standards over a range that covers 0.1 {or RQL whichever is higher} to 2 times the target 

8.0

8.5

9.0

9.5

10.0

7.0 7.5 8.0 8.5 9.0

1

Time (min)

Response (m

V) Figure 4.2.2. Chromatogram of the RQL (1: ____ 

{analyte}). 

38 of 59 
concentration for the sampler with the highest mass loading. A calibration curve was 

constructed and shown in Section 3.5.2 from the three injections of five standards. The 

standard error of estimate was ____ {mass}. 

Table 4.3 

Instrument Calibration 

Η target 0.1Η 0.5Η 1.0Η 1.5Η 2.0Η

concn 

(μg/sample) 123 615 1230 1845 2461 

area counts 

(μV·s) 

4772 

4770 

4799 

23988

23738

23741

47783 71790 95054

47593 71490 95987

47895 71901 95616

 4.4 Storage stability test {Describe the storage test, including preparation of samples.} 

 4.4.1 ____ {Active sampler} 

 Storage samples for ____ {analyte} were prepared by sampling a dynamically 

generated controlled test atmosphere using the recommended sampling parameters. 

The concentration of ____ {analyte} in the test atmosphere was the target 

concentration (____ppm or ____mg/m3

), and the relative humidity was ____ {RH} at 

____ {temp} ΕC. Thirty-three storage samples were prepared. Three samples were 

analyzed on the day of generation. Fifteen samples were stored at reduced 

temperature (4ΕC) and the other fifteen were stored in a closed drawer at ambient 

temperature (about ____ {temp}ΕC). At 2-5 day intervals {preferably 3-day intervals}, 

three samples were selected from each of the two storage sets and analyzed. Sample 

results are not corrected for extraction efficiency. 

 Table 4.4.1 

Storage Test for ____ {Analyte} 

time 

(days) 

ambient storage 

 

0

25

50

75

100

125

0 5 10 15

{Analyte} Ambient Storage

y = 0.135x + 100.3

Overall Std Error of Estimate = 5.15%

95% Confidence Limits = ±(1.96)(5.15%) = ±10.1%

Storage Time (Days)

Recovery (%)

0

25

50

75

100

125

0 5 10 15

{Analyte} Referigerated Storage

y = 0.101x + 99.4

Overall Std Error of Estimate = 5.33%

95% Confidence Limits = ±(1.96)(5.33%) = ±10.4%

Storage Time (Days)

Recovery (%)

recovery (%) 

refrigerated storage 

recovery (%) 

0 100.5 99.9 100.7 100.5 99.9 100.7 

4 98.6 100.9 100.3 97.4 96.2 98.7 

7 102.6 100.9 101.2 101.5 98.8 100.9 

11 102.7 104.8 101.6 101.9 101.9 102.4 

14 101.9 101.0 102.7 100.2 98.8 103.2 

18 101.1 103.8 101.9 100.7 98.4 102.8 

Figure 4.4.1.2. Refrigerated storage test for ____ 

{analyte}. Figure 4.4.1.1. Ambient storage test for ____ {analyte}. 

39 of 59 
 

 4.4.2 ____ {Diffusive sampler} 

 Storage samples for ____ {analyte} were prepared sampling a dynamically generated 

controlled test atmosphere using the recommended sampling time. The concentration 

of ____ {analyte} in the test atmosphere was the target concentration (____ ppm or 

____mg/m3

), and the relative humidity was ____ {RH} at ____ {temp} ΕC. Thirty-three 

storage samples were prepared. Three samples were analyzed on the day of 

generation. Fifteen of the samplers were stored at reduced temperature (4ΕC) and the 

other fifteen were stored in a closed drawer at ambient temperature (about ____ {temp}

ΕC). At 2-5 day intervals {preferably 3-day intervals}, three samples were selected 

from each of the two storage sets and analyzed. Sample results are not corrected for 

extraction efficiency. Results were calculated using the sampling rate determined in 

Section 4.7 converted to its equivalent sampling rate at sampling site temperature and 

pressure. 

Table 4.4.2 

Storage Test for ____ {Analyte} 

time 

(days) 

ambient storage 

recovery (%) 

refrigerated storage 

recovery (%) 

0 

4 

7 

11 

14 

16 

103.5

99.6 

100.0

100.8

95.6 

96.5 

101.6

100.5

101.9 103.5 101.6 101.9 

95.8 99.3 99.4 101.8 

95.8 

105.5 

97.5 

99.1 

95.8 93.8 95.9 

100.6

100.9

98.8 100.2 103.6

96.6 99.1 98.9 99.6 

94.5 98.8 99.3 99.5 

125 125

0

25

50

75

100

0 5 10 15

{Analyte} Ambient Storage

y = -0.260x + 100.8

Overall Std Error of Estimate = 6.84%

95% Confidence Limits = ±(1.96)(6.84%) = ±13.4%

Storage Time (Days)

Recovery (%)

0

25

50

75

100

0 5 10 15

{Analyte} Referigerated Storage

y = 0.101x + 99.4

Overall Std Error of Estimate = 5.33%

95% Confidence Limits = ±(1.96)(5.33%) = ±10.4%

Storage Time (Days)

Recovery (%)

Figure 4.4.2.1. Ambient storage test for ____ {analyte}. Figure 4.4.2.2. Refrigerated storage test for ____

{analyte}. 

 

 4.5 Precision (overall procedure) 

 

 The precision of the overall procedure at the 95% confidence level is obtained by multiplying 

the overall standard error of estimate by 1.96 (the z-statistic from the standard normal 

distribution at the 95% confidence level). Ninety-five percent confidence intervals are drawn 

about the regression lines in the storage stability figures shown in Section 4.4. 

 4.5.1 ____ {Active sampler} 

40 of 59 
 The precession of the overall procedure at the 95% confidence level for the ambient 

temperature {or reduced temperature (____ΕC)} 15-day storage test (at the target 

concentration) is ∀____ %. It was obtained from the overall standard error of estimate 

(____ %) of the data shown in Figure ____. It contains an additional 5% for sampling 

pump error. {The standard error of estimate listed on the cover page of the method 

and in this section must be based on the storage data that reflects the temperature 

recommended for shipment and storage of samples.} 

 

 4.5.2 ____ {Diffusive sampler} 

 The precisions of the overall 

procedure at the 95% confidence 

level for the ambient temperature 

{or reduced temperature (____

ΕC)} 15-day storage test (at the 

target concentration) for ____ 

{diffusive sampler} are given in 

Table 4.5.2. They each include an 

additional ____% for sampling rate 

variation18,19. There are different values given, depending on whether both, either, or 

neither temperature (T) or atmospheric pressure (P) are known at the sampling site. If 

the sampling site temperature is unknown, it is assumed to be 22.2 ± 15ΕC (72 ± 27

ΕF) and a variability of ±7.7% is included. If the atmospheric pressure is not known, it 

is estimated from the sampling site elevation and a variability of ±3% is included. {The 

standard error of estimate listed on the cover page of the method and in this section 

must be based on the storage data that reflects the temperature recommended for 

shipment and storage of samples. Temperature and barometric pressure are known 

conditions for storage samples.} 

Table 4.5.2 

Overall Standard Error of Estimate 

and Precision of the Overall Procedure 

known condition error (%) precision (∀%) 

both T & P

only T

only P

neither T nor P

____ 

____ 

____ 

____ 

____ 

____ 

____ 

____ 

 4.5.3 Recovery 

 The recovery of ____ {analyte} from samples used in a ____-day storage test remained 

above ____ % and ____% {the lowest points on the respective regression curves of 

Section 4.5} when the samples were stored at ____ΕC for ____ {active sampler} and 

____ {diffusive sampler}, respectively. (Or if the case requires: The recovery of ____ 

{analyte} from samples used in a ____-day storage test remained above 75% for the 

first ____ days when samples were stored at ____ΕC.) {Use the same storage data as 

used for precision to calculate recovery} 

 4.6 Reproducibility {Describe reproducibility test and present data in Tables 4.6.1 and 4.6.2. 

Specify that the "amount found" is corrected for extraction efficiency.} 

 Example: 

 Six samples were prepared for both types of sampler by sampling a dynamically generated 

controlled test atmosphere similar to that used in the collection of the storage samples. The 

concentration of ____ {analyte} in the test atmosphere was the target concentration (____ ppm 

or ____mg/m3

), and the relative humidity was ____ {RH} at ____ {temp} ΕC. The samples 

were submitted to the OSHA Salt Lake Technical Center for analysis. The samples were 

analyzed after being stored for ____ days at ____ΕC. Sample results were corrected for 

extraction efficiency. No sample result for ____ {analyte} had a deviation greater than the 

 

18 Hendricks, W. Development of a Protocol for Laboratory Testing of Diffusive Samplers, 1996. United States Department of 

Labor, Occupational Safety & Health Administration. http://osha.gov/dts/sltc/methods/studies/3movm/3movm.html (accessed 

January 7, 2009). 19 Hendricks, W. Determination of the Sampling Rate Variation for SKC 575 Series Passive Samplers, 1998. United States 

Department of Labor, Occupational Safety & Health Administration. 

http://osha.gov/dts/sltc/methods/studies/skc575/skc575.html (accessed January 7, 2009).

41 of 59 
precision of the overall procedure determined in Section 4.5. Theoretical masses for ____ 

{diffusive sampler} were determined using the sampling rate determined in Section 4.7 

converted to its equivalent sampling rate at sampling site temperature and atmospheric 

pressure. 

 

Table 4.6.1 Table 4.6.2 

Reproducibility Data for ____ {Analyte} Reproducibility Data for ____ {Analyte} 

Collected on ____ {Active Sampler} Collected on ____ {Diffusive Sampler} 

 4.7 Sampler capacity {add "and sampling rate for ____diffusive samplers}" if appropriate {Describe 

breakthrough or other studies used.} 

 4.7.1 ____ {Active sampler} 

 

 The sampling capacity of the front section of an ____ {active sampler} was tested by 

sampling a dynamically generated controlled test atmosphere containing ____ {analyte} 

at two times the target concentration (____ppm or ____ mg/m3

) and ____ {RH} relative 

humidity at ____ {temp} ΕC. The samples were collected at ____ mL/min. A GC 

equipped with a gas sampling valve and an FID was placed in-line behind the front test 

section and was used to monitor the effluent from the sampling tube every 5 min. The 

recommended sampling time is ____ hours. 

theoretical 

(μg/sample) 

recovered 

(μg/sample) 

recovery 

(%) 

deviation theoretical recovered 

(μg/sample)

recovery 

(%) (μg/sample) (%) 

deviation 

(%) 

420.6 

420.6 

420.6 

420.6 

420.6 

420.6 

420.6 

420.6 

420.6 

420.6 

420.6 

388.6 

395.5 

393.2 

379.6 

379.0 

406.1 

92.4 

94.0 

93.5 

90.3 

90.1 

96.6 

!7.6 

!6.0 

!6.5 

!9.7 

!9.9 

!3.4 

388.6 

395.5 

393.2 

379.6 

379.0 

406.1 

92.4 

94.0 

93.5 

90.3 

90.1 

96.6 

!7.6 

!6.0 

!6.5 

!9.7 

!9.9 

420.6 !3.4 

0

2

4

6

8

10

0 500 1000 1500

Air Volume (L)

Breakthrough (%)

Figure 4.7.1. Five-percent breakthrough air volume for 

____{analyte}.

Table 4.7.1 

Breakthrough of ____ {Analyte} 

From Front Section of ____ {Active Sampler} 

test 

no. 

air vol 

(L) 

sampling 

time 

(min) 

downstream 

concn 

(mg/m3

) 

breakthrough

(%) 

1 

2 

3 

14.2 

15.8 

18.7 

21.5 

23.0 

24.5 

13.8 

16.0 

19.3 

22.0 

23.3 

24.8 

13.5 

15.5 

18.5 

21.8 

22.5 

25.0 

285 

315 

375 

430 

460 

490 

275 

320 

385 

440 

465 

495 

270 

310 

370 

435 

450 

500 

0.00 

0.00 

0.72 

1.96 

2.91 

3.94 

0.00 

0.31 

0.84 

2.04 

3.15 

4.11 

0.00 

0.21 

0.75 

1.85 

3.20 

4.20 

0.0 

0.0 

1.02 

2.78 

4.13 

5.59 

0.0 

0.44 

1.19 

2.90 

4.47 

5.84 

0.0 

0.30 

1.07 

2.63 

4.55 

5.97 

42 of 59 
 

43 of 59 
 4.7.2 ____ {Diffusive sampler} 

 The sampling rate and sampler capacity for ____ {diffusive sampler} were determined 

by sampling a dynamically generated controlled test atmosphere for increasing time 

intervals. Sampler capacity is exceeded when the plotted sampling rate decreases 

rapidly as the sampler becomes saturated. The concentration of the test atmosphere 

was two times the target concentration (____ ppm or ____ mg/m3

) at ____ {RH} 

relative humidity and ____ {temp} ΕC. The preliminary sampling rate was determined 

by averaging the nine values for the 0.5, 1 and 2 hour samples. Horizontal lines were 

placed 10% above and 10% below the preliminary sampling rate. The sampling rate is 

____ mL/min at 760 mmHg and 25ΕC and represents the average of all values 

between the lines. The standard deviation and RSD are ____ mL/min and ____%, 

respectively. The data obtained are shown in Table 4.7.2 and Figure 4.7.2. Mass 

collected is corrected for extraction efficiency. The recommended sampling time is 

____ hours. 

Table 4.7.2 

Determination of Sampling Rate and Time 

sampling rate (mL/min) 

time (h) first second third 

0.083 

0.167 

0.5 

1 

2 

3 

4 

6 

8 

10 

12.4 

12.3 

12.1 

12.0 

12.1 

12.0 

11.8 

11.4 

10.9 

10.6 

12.5 

12.4 

12.2 

12.2 

12.2 

12.1 

11.9 

11.5 

11.0 

10.7 

12.6 

12.5 

12.3 

12.3 

12.4 

12.2 

12.0 

11.6 

11.1 

10.5 

 

4.8 Extraction efficiency and stability of extracted samples 

 The extraction efficiency is affected by the extraction solvent, the internal standard, the 

sampling medium, and the technique used to extract the samples. Other reagents and 

techniques than described in this method can be used provided they are tested as specified in 

the validation guidelines.20 

 4.8.1 ____ {Active sampler} 

 Extraction efficiency 

 The extraction efficiency of ____ {analyte} was determined by liquid-spiking four ____ 

{active sampler} at each concentration level. These samples were stored overnight at 

ambient temperature and then analyzed. The overall mean extraction efficiency over 

the working range of 0.1 to 2 times the target concentration was ____%. The 

9

10

11

12

13

14

2 4 6 8 10

Time (hours)

Sampl ni g Rate (mL/m ni )

Figure 4.7.2. Example of plotted data to determine 

the sampling rate and recommended sampling time. 

 

20 Eide, M.; Simmons, M.; Hendricks, W. Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis, 2010. 

United States Department of Labor, Occupational Safety & Health Administration. 

http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf (accessed March 11, 2010).

44 of 59 
extraction efficiency at the RQL was ____%. The presence of water had no significant 

effect on extraction efficiency. The extraction efficiencies for the RQL and for the wet 

samplers are not included in the overall mean. Wet media were prepared by drawing 

humid air (____ {RH} relative humidity at ____ {temp} °C) at ____ {recommended 

sampling rate} for ____ {recommended sampling time}. The data obtained are shown 

in Table 4.8.1.1. 

Table 4.8.1.1 

Extraction Efficiency of ____ {Analyte} from ____ {Active Sampler} 

level sample number

Η target 

concn 

μg per 

sample 1 2 3 4 mean 

0.1 

0.25 

0.5 

1.0 

1.5 

2.0 

21.0 99.8 97.5 

RQL 

1.0 (wet) 

52.5 

105 

210 

315 

420 

2.08 

210 

103.5 99.5 

101.6 102.4 

101.9 101.8 

105.8 105.0 

95.8 92.8 

90.4 95.1 

99.6 

99.9 

99.6 

100.5 

95.8 

100.4 

97.7 

87.6 

104.3 94.7 

101.2 

100.0 

95.8 

100.2 

94.2 

97.7 

90.0 

100.5 

99.6 

100.6 

100.1 

99.9 

101.4 

96.0 

90.8 

99.8 

 

 Stability of extracted samples 

 The stability of extracted samples was examined by reanalyzing the target 

concentration samples 24, 48, and 72 hours after the initial analysis. After the original 

analysis was performed two vials were recapped with new septa which were replaced 

after each reanalysis. The remaining two vials retained their punctured septa 

throughout the test. All samples were allowed to stand in the autosampler tray at 

{ambient} temperature. The samples were reanalyzed with freshly prepared standards. 

Diff is the difference between the initial analysis and the subsequent analysis. Each 

septum was punctured ____ times for each injection. The data obtained are shown in 

Table 4.8.1.2. 

 

Table 4.8.1.2 

Stability of Extracted Samples for ____ {Analyte} 

punctured septa replaced punctured septa retained

initial 

(%) 

24 h 

(%) 

diff 

 (%) 

48 h 

(%) 

diff 

 (%) 

72 h 

(%) 

diff 

 (%) 

initial 

(%) 

24 h 

(%) 

diff 

 (%) 

48 h 

(%) 

diff 

 (%) 

72 h 

(%) 

diff 

 (%) 

101.9 

101.8 

101.9 

99.9 

101.2 

100.6 

-2.0 

-0.6 

103.5 +1.6 100.5 

97.8 

-1.3 

99.5 

mean 

101.5 

-2.3 

-0.4 99.2 

-1.4 

-4.0 

-2.7 

95.8 

100.2 

98.0 

95.9 

97.9 

96.9 

+0.1 

-2.3 

-1.1 

99.8 

97.5 

mean 

98.6 

+4.0 

-2.7 

+0.6 

100.6 

102.4 

101.5 

+4.8 

+2.2 

+3.5 

 4.8.2 ____ {Diffusive sampler} 

 Extraction efficiency 

 The extraction efficiency of ____ {analyte} was determined by liquid-spiking four ____ 

{diffusive sampler} at each concentration level. These samples were stored overnight 

at ambient temperature and then extracted and analyzed. The overall mean extraction 

efficiency over the range of 0.1 to 2 times the target concentration was ____%. The 

extraction efficiency at the RQL was ____%. The presence of water had no significant 

effect on extraction efficiency. The extraction efficiencies for the RQL and for the wet 

samplers are not included in the overall mean. Wet media were prepared by exposing 

45 of 59 
the samplers to humid air (____ {RH} relative humidity at ____ {temp} °C) for ____ 

{recommended sampling time}. The data obtained are shown in Table 4.8.2.1. 

Table 4.8.2.1 

Extraction Efficiency of ____ {Analyte} from ____ {Diffusive Sampler} 

level sample number

Η target 

concn 

μg per 

sample 1 2 3 4 mean 

0.1 

0.25 

0.5 

1.0 

1.5 

2.0 

RQL 

1.0 (wet) 

12.6 

31.5 

63.0 

126 

189 

252 

4.06 

126 

98.8 99.1 

101.6 103.4 

102.4 99.9 

101.2 100.8 

95.8 92.8 

102.8 104.0 

96.8 99.8 

99.5 

99.0 

100.9 

95.7 

95.9 

97.7 

100.1 

98.7 

103.5 99.6 

100.0 

96.7 

98.0 

101.0 

97.7 

99.4 

98.7 

100.0 

99.2 

100.7 

99.0 

99.7 

96.0 

101.6 

98.5 

100.6 

 

 Stability of extracted samples 

 The stability of extracted samples was examined by reanalyzing the target 

concentration samples 24, 48, and 72 hours after the initial analysis. After the original 

analysis was performed two vials were recapped with new septa which were replaced 

after each reanalysis. The remaining two vials retained their punctured septa 

throughout the test. All samples were allowed to stand in the autosampler tray at 

{ambient} temperature. The samples were reanalyzed with freshly prepared standards. 

Diff is the difference between the initial analysis and the subsequent analysis. Each 

septum was punctured ____ times for each injection. The data obtained are shown in 

Table 4.8.2.2. 

Table 4.8.2.2 

Stability of Extracted Samples for ____ {Analyte} 

punctured septa replaced punctured septa retained

initial 

(%) 24 h (%) diff  (%) 

48 h 

(%) 

diff 

 (%) 

72 h 

(%) 

diff 

 (%) 

initial 

(%) 

24 h 

(%) 

diff 

 (%) 

48 h 

(%) 

diff 

 (%) 

72 h 

(%) 

diff 

 (%) 

101.2 

100.5 

100.9 

99.8 

98.8 

99.3 

-1.4 

-1.7 

97.7 -3.5 98.2 -3.0 

-1.9 

-2.5 

95.9 

101.0 

98.5 

100.8 

99.4 

100.1 

+4.9 

-1.6 

+1.6 

100.1 

99.4 

mean 

99.8 

+4.2 

97.7 -2.8 98.6 

mean 

-1.6 97.7 -3.2 98.4 

-1.6 

-1.3 

97.1 

99.8 

98.5 

+1.2 

-1.2 

0.0 

 

 4.9 Sampling interferences {use tables to present data when appropriate} 

 The tested sampling interferences had no significant effect on the ability of {sampler} to collect 

or retain ____{analyte}. {Or if any of the tested interferences has a significant effect on 

sampling, this fact and the remedy must be listed here and in the appropriate subsection(s) of 

Section 2.} 

 

46 of 59 
 4.9.1 ____ {Active sampler} 

 Retention 

 

 Retention was tested by sampling a 

dynamically generated controlled test 

atmosphere containing two times the 

target concentration (____ ppm or____ 

mg/m3

) of ____ {analyte} at ____ {RH} 

relative humidity and ____ {temp} ΕC. 

The test atmosphere was sampled with 

six ____ {sampler} at ____ mL/min for 

____ min. {one-quarter of the recommended sampling time}. Sampling was 

discontinued and the samplers were separated into two sets of 3 samplers each. The 

generation system was flushed with contaminant-free air. Contaminant-free air is 

laboratory conditioned air at known relative humidity and temperature but without any 

added chemical except water. Sampling was resumed with a set of three samples and 

contaminant-free air at ____ {RH} relative humidity and ____ {temp} ΕC at ____ 

mL/min for ____ min {three-quarters of the recommended sampling time} and then all 

six samplers were analyzed. The data obtained are shown in Table 4.9.1. 

 Low humidity 

 The effect of low humidity was tested by sampling a dynamically generated controlled 

test atmosphere containing two times the target concentration (____ ppm or ____ 

mg/m3

) of ____ {analyte} at ____ {RH} relative humidity and ____ {temp} ΕC. The test 

atmosphere was sampled with three ____ {sampler} at ____ mL/min for ____ min {the 

recommended sampling time}. All of the samples were immediately analyzed. Sample 

results were ____%, ____%, and ____% of theoretical. 

Table 4.9.1 

Retention of ____ {Analyte} 

on ____ {Active Sampler} 

 recovery (%) 

set 1 2 3 mean 

first 

second 

second/first 

99.6 

100.4 

98.2 

100.1 

100.0 

100.2 

99.3 

100.2 

100.9 

 Low concentration 

 The effect of low concentration was tested by sampling a dynamically generated 

controlled test atmosphere containing 0.1 times the target concentration (____ ppm or 

____ mg/m3

) of ____ {analyte} at ____ {RH} relative humidity and ____ {temp} °C. The 

test atmosphere was sampled with three ____ {sampler} at ____ mL/min for ____ min 

{the recommended sampling time}. All of the samples were immediately analyzed. 

Sample results were ____%, ____%, and ____% of theoretical. 

Chemical interference 

 The effect of potential chemical sampling interference(s) was tested by sampling a 

dynamically generated controlled test atmosphere containing one times the target 

concentration (____ ppm or ____ mg/m3

) of ____ {analyte} at ____ {RH} relative 

humidity and ____ {temp} ΕC and the interference(s). The interference(s) were {list 

interference(s) and concn(s)}. The test atmosphere was sampled with three ____ 

{sampler} at ____ mL/min for ____ min {the recommended sampling time}. All of the 

samples were immediately analyzed. Sample results were ____%, ____%, and ____% 

of theoretical. 

 

47 of 59 
 4.9.2 ____ {Diffusive sampler} 

 Reverse diffusion 

 Reverse diffusion was tested by 

sampling a dynamically generated 

controlled test atmosphere 

containing two times the target 

concentration (____ ppm or ____ 

mg/m3

) of ____ {analyte} at ____ 

{RH} relative humidity and ____ 

{temp} ΕC. Six samplers were 

exposed to the test atmosphere for ____ min {one-quarter of the recommended 

sampling time}. Sampling was discontinued and the samplers were separated into two 

sets of 3 samplers each. The generation system was flushed with contaminant-free air. 

Sampling was resumed with a set of three samples exposed to contaminant-free air at 

____ {RH} relative humidity and ____ {temp} ΕC for ____ min {three-quarters of the 

recommended sampling time} and then all six samplers were analyzed. The data 

obtained are shown in Table 4.9.2. Reverse diffusion was less than ____%. 

Table 4.9.2 

Reverse Diffusion of 

____ {Analyte} From ____ {Diffusive Sampler} 

mass (μg) 

set 1 2 3 mean 

first 

second 

second/first

212.0 

203.4 

209.2 

201.1 

204.0 

204.2 

208.4 

202.9 

97.4 

 Low humidity 

 The effect of low humidity was tested by sampling a dynamically generated controlled 

test atmosphere containing two times the target concentration (____ ppm or ____ 

mg/m3

) of ____ {analyte} at ____ {RH} relative humidity and ____ {temp} ΕC. Three 

samplers were exposed to the test atmosphere for ____ min {the recommended 

sampling time}. All of the samples were immediately analyzed. Results were 

calculated using the average sampling rate determined in Section 4.7 converted to its 

equivalent sampling rate at sampling site temperature and pressure. The results were 

____%, ____%, and ____% of theoretical. 

 

 Low concentration 

 The effect of low concentration was tested by sampling a dynamically generated 

controlled test atmosphere containing 0.1 times the target concentration (____ ppm or 

____ mg/m3

) of ____ {analyte} at ____ {RH} relative humidity and ____ {temp} ΕC. 

Three samplers were exposed to the test atmosphere for ____ min {the recommended 

sampling time}. All of the samples were immediately analyzed. Results were 

calculated using the average sampling rate determined in Section 4.7 converted to its 

equivalent sampling rate at sampling site temperature and pressure. The results were 

____%, ____%, and ____% of theoretical. 

 Chemical sampling interference 

 The effect of potential chemical sampling interference(s) was tested by sampling a 

dynamically generated controlled test atmosphere containing one times the target 

concentration (____ ppm or ____ mg/m3

) of ____ {analyte} at ____ {RH} relative 

humidity and ____ {temp} ΕC and the interference(s). The interference(s) were {list 

interference(s) and concn(s)}. Three samplers were exposed to the test atmosphere 

for ____ min {the recommended sampling time}. All of the samples were immediately 

analyzed. Results were calculated using the average sampling rate determined in 

Section 4.7 converted to its equivalent sampling rate at sampling site temperature and 

pressure. The results were ____%, ____%, and ____% of theoretical. 

 

48 of 59 
 4.10 Qualitative analysis 

 

 {GC/MS may provide conclusive peak 

identification and should be addressed in 

all cases, even when the discussion 

amounts to why it is not possible or not 

available. Use the format of Section 3.5.1 

to present GC/MS conditions if the mass 

spectrum was generated using in-house 

instrumentation. Be sure to include 

relevant MS conditions. The format for 

mass spectra is shown in Figure 4.10. 

Include a citation if the included mass 

spectrum was taken from a library. It is 

not necessary to list GC/MS conditions if 

the spectrum was taken from a library. 

Use the same format to present analytical 

conditions if alternate means for qualitative 

analysis are presented.} 

0

2000

4000

6000

8000

10000

0 20 40 60 80 100

73

29

43

45

88

m/z

Abundance

Figure 4.10. Mass spectrum of ____ {analyte}. 

 

 Example 

GC/MS conditions

oven temperature: 60 °C (hold 1 min), ramp to 225 °C at 15 °C/min (hold 3 min) 

injector temperature: 250 °C 

detector temperature: 300 °C 

run time: 15 min 

column: Supelco SPB-5 capillary column, 60-m × 0.32-mm i.d, df = 1.0-

μm, or equivalent 

column mode: constant pressure (14 psi) {or constant flow} 

initial column gas flow: 1.2 mL/min (helium) 

septum purge: 1.5 mL/min (helium) 

injection size: 1.0 μL (10 to 1 split) 

inlet liner: Agilent 5183-4647 or equivalent 

MS conditions

MS temperatures 

mass range 

etc.

 

49 of 59 
 4.11 Generation of test atmospheres 

 {Describe the apparatus used to generate and sample test atmospheres and include a diagram 

if possible.} 

 Example 

 Test atmospheres were generated from ____ 

solutions containing ____ {analyte}. 

Isco 

pump 

 

Miller Nelson controller 

Mixing 

chamber 

Diffusive sampler exposure 

chamber

Active samplers 

Vapor 

generator 

exit 

The apparatus was placed in a walk-in hood. 

Test atmospheres were generated by 

pumping low microliter volumes of the ____ 

{analyte} solution with an Isco precision HPLC 

pump through a short length of 0.53-mm 

diameter uncoated fused silica capillary tubing 

into a vapor generator where it was heated 

and evaporated into a dilution air stream 

(Figure 4.11). The vapor generator was a 

short length of glass tubing with a side port for 

introduction of the capillary tubing. The vapor 

generator was heated with a variable voltagecontrolled heating tape to evaporate the ____ 

{analyte} solution. The humidity, temperature, 

and volume of dilution air of were regulated by 

use of a Miller Nelson Flow-TemperatureHumidity controller. The test atmosphere 

passed from the vapor generator into a glass 

mixing chamber, and then into a glass 

exposure chamber where samples could be 

collected. Active samplers were connected to glass ports extending from the exposure 

chamber and diffusive samplers were placed inside the chamber. The air velocity through the 

exposure chamber was approximately 0.4 m/sec. The humidity and temperature were 

measured at the exit of the exposure chamber with an Omega Digital Thermo-hygrometer. 

Figure 4.11. The test atmosphere generation and 

sample collection apparatus. 

50 of 59 
PREPARATION OF WRITTEN REPORTS FOR PARTIALLY VALIDATED METHODS 

Each partially validated method will be assigned a version number beginning with the number "1.0". 

Significant changes or revisions to the method require that a new version number be assigned, for 

example "2.0". If the document is revised, the date revised will be placed on the cover page and a 

discussion concerning the revision included in Section 1.1.1 History. 

. 

Partially validated methods will include data on the following items:

 1. Background information - Include the purpose of the work, physical properties, and other easily 

acquired information that would normally be reported in the Background Section of a fully validated 

method. 

 2. Detection limit of the overall procedure (DLOP) - Determine this parameter in the same manner as 

in a full validation. 

 3. Reliable quantitation limit (RQL) - Determine this parameter in the same manner as in a full 

validation. 

 4. Extraction efficiency - Determine these parameters over the working rage of 0.1 to 2 times the 

target concentration in the same manner as in a full validation. Determine the extraction efficiency 

at one times the target concentration using wet media. Determine the extraction efficiency at the 

RQL. Do not include the extraction efficiency from wet media or at the RQL in the overall average. 

 5. Retention efficiency - The recommended sampling time and sampling rate will be based, at least in 

part, on retention efficiency. Perform retention efficiency tests with loadings equivalent to two times 

the target concentration using humid air at an absolute humidity of 15.7 milligrams of water per liter 

of air (about 80% at 22.2 ΕC). The minimum length of time that the retention efficiency test must 

be conducted is 1.25 times the sampling time recommended in the method. 

 6. Storage stability test – Perform a storage stability test with spiked samples at loadings equivalent to 

the target concentration. The recommended volume of humid air (absolute humidity of 15.7 

milligrams of water per liter of air (about 80% at 22.2 ΕC)) will be drawn through the samplers at the 

recommended sampling rate before storage. Prepare 12 spiked samples, store them at ambient 

temperature in the dark, and analyze three samples approximately every five days over two weeks. 

It may be necessary to perform another storage stability test at refrigerated temperature if instability 

is observed at ambient temperature. 

 7. Recommendation for further study - Recommendations will be made that should be considered 

before a full validation is performed. 

Prepare written partially validated methods according to the following outline. This outline is similar to 

that used for a fully validated method except that the validation data is included in the various method 

sections instead of in a separate Backup Data section. Use the guidelines for Fully Validated Methods as 

a reference for more specific format details. 

Required statements concerning the status of the method, accessibility problems, intended use of the 

method, manufacturer disclaimer, toxic effects disclaimer, reference to OSHA Methods Development 

Guidelines, basis of cited air concentrations, sampling safety, chemical hygiene plan, analytical safety, 

and QA practices are placed at certain points in the method text. These required statements will not be 

altered and will be inserted in the locations shown in the example partially validated method. 

51 of 59 
Text formatting, instructions for field and laboratory personnel, and descriptive discussion shown in the 

example partially validated method will not be altered unless such text in clearly inaccurate or 

inappropriate. 

The purpose of section and paragraph indents is to delineate text and to provide a convenient way to 

reference sections and paragraphs in subsequent sections and paragraphs. Indents should be used as 

shown in the example partially validated method unless additional indents are necessary for clarity. 

Quaternary indents, for example 3.4.1.1, will be avoided whenever possible. 

52 of 59 
{ANALYTE} 

{as listed in CFR or ACGIH} 

Method number: PV2xxx

Version: x.0 

Target concentration: ____ ppm (____ mg/m3

) 

OSHA PEL: ____ ppm (____ mg/m3

) {None if no PEL} 

ACGIH TLV: ____ ppm (____ mg/m3

) {None if no TLV} 

{Include skin designations when applicable} 

Procedure: Samples are collected by drawing workplace air through ____ with 

personal sampling pumps. Samples are extracted with ____ and 

analyzed by ____ using a ____ detector. 

Recommended sampling time 

and sampling rate: ____ min at ____ mL/min (____ L) 

 

Reliable quantitation limit: ____ ppm (____ mg/m3

) 

Special requirements: {If none, delete this item} 

Status of method: Partially validated method. This method has been subjected to the 

established validation procedures of the Methods Development Team 

and is presented for information and trial use. 

____ {month year} {Chemist} ____ 

Date revised: ____ (month year} 

{Branch} Analytical Services 

Industrial Hygiene Chemistry Division 

OSHA Salt Lake Technical Center 

Sandy UT 84070-6406 

53 of 59 
1. General Discussion 

 For assistance with accessibility problems in using figures and illustrations presented in this method, 

please contact the Salt Lake Technical Center (SLTC) at (801) 233-4900. This procedure was 

designed and tested for internal use by OSHA personnel. Mention of any company name or 

commercial product does not constitute endorsement by OSHA. 

 

 1.1 Background 

 1.1.1 History 

 {Explain the purpose of this work. Also, obvious questions that may be raised by 

knowledgeable readers should be addressed. Keep length at 1 to 1.5 pages or less.} 

 1.1.2 Toxic effects (This section is for information only and should not be taken as the basis 

of OSHA policy.) 

 {Cite sources for presented information. If both animal data and human data are 

presented, present the animal data first. If the entire section is taken from one 

reference, the reference notation can be placed behind the qualifying statement in the 

heading.} 

 1.1.3 Workplace exposure 

 {Report major sources of exposure in the workplace and, if available the size of the 

work population that is exposed. If the entire section is taken from one reference, the 

reference notation can be placed behind the heading.} 

 1.1.4 Physical properties and other descriptive information21 {these are examples that can 

be used if applicable, other physical properties can also be listed.} 

 synonyms: ____ 

 solubility: ____ 

 IMIS number22: ____ appearance: ____ 

 CAS number: ____ vapor pressure: {kPa (mmHg)} ____ 

 molecular weight: ____ flash point: ____ 

 boiling point: ____ odor: ____ 

 melting point: ____ lower explosive limit: ____ 

 8max: ____ specific gravity: ____ 

 structural formula: ____ molecular formula: ____ 

This method was validated according to the OSHA SLTC “Validation Guidelines for Air Sampling Methods 

Utilizing Chromatographic Analysis”23. The Guidelines define analytical parameters, specify required 

laboratory tests, statistical calculations, and acceptance criteria. The analyte air concentrations 

throughout this method are based on the recommended sampling and analytical parameters. Air 

concentrations listed in ppm are referenced to 25ΕC and 760 mmHg (101.3 kPa). 

 

21 This reference was used for most of the physical properties. 22 Chemical Sampling Information. U.S. Department of Labor, Occupational Safety and Health Administration Web site. 

http://osha.gov/dts/chemicalsampling/toc/toc_chemsamp.html (accessed March 11, 2009). 23 Eide, M.; Simmons, M.; Hendricks, W. Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis, 2010. 

United States Department of Labor, Occupational Safety & Health Administration. 

http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf (accessed March 11, 2010).

54 of 59 
1.2 Detection limit of the overall procedure (DLOP) and reliable quantitation limit (RQL) 

 Example: 

 The DLOP is measured as mass per sample and expressed as equivalent air concentrations, 

based on the recommended sampling parameters. Ten samplers were spiked with equally 

descending increments of analyte, such that the highest sampler loading was ____ μg/sample. 

This is the amount spiked on a sampler that would produce a peak approximately 10 times the 

response for a sample blank. These spiked samplers and the sample blank were analyzed with 

the recommended analytical parameters, and the data obtained were used to calculate the 

DLOP. Values of ____ and ____ were obtained for the slope and SEE respectively. The data 

obtained are shown in Table 1.2 and Figure 1.2.1. DLOP was calculated to be ____ μg/sample 

(____ ppm or ____ mg/m3

). 

0

300

600

900

1200

1500

0 0.2 0.4 0.6 0.8 1.0

RQL

DLOP

Mass (μg) per Sample

Area Counts (μV•s)

Table 1.2 

Detection Limit of the Overall Procedure 

mass per sample area counts 

(μg) (μV-s) 

0 0 

0.421 0 

0.841 178 

1.26 177 

1.68 375 

2.10 536 

2.52 696 

2.94 703 

3.36 810 

3.78 948 

4.21 1150 

 Figure 1.2.1. Plot of data to determine the DLOP/RQL 

(y = 277x – 75.5).

The RQL is the lower limit for precise quantitative measurements. It is determined from the 

regression line parameters obtained from the calculation of the DLOP, providing 75% to 125% 

of the analyte is recovered. The RQL is ____ μg per sample (____ ppm or ____ mg/m3

). 

Recovery at this concentration is ____%. 

8.0

8.5

9.0

9.5

10.0

7.0 7.5 8.0 8.5 9.0

1

Time (min)

Response (m

V) Figure 1.2.2. Chromatogram of the RQL (1: ____ 

{analyte}). 

55 of 59 
2. Sampling Procedure {Refer to the cited sections in the Fully Validated Method example for format 

detail. Use paragraphs instead of tertiary subsections} 

All safety practices that apply to the work area being sampled should be followed. The sampling 

equipment should be attached to the worker in such a manner that it will not interfere with the work 

performance or safety. 

 2.1 Apparatus {Section 2.1} 

 2.2 Reagents {if no reagents are required, state "None required". Otherwise use the format 

described in Section 3.2} 

 2.3 Technique {Section 2.3} 

 2.4 Extraction efficiency 

 

 The extraction efficiency is affected by the extraction solvent, the internal standard, the 

sampling medium, and the technique used to extract the samples. Other reagents and 

techniques than described in this method can be used provided they are tested as specified in 

the validation guidelines.24 

 Example 

 The extraction efficiencies of ____ {analyte} were determined by liquid-spiking ____ {sampler} 

with the analyte at 0.1 to 2 times the target concentration. These samples were stored 

overnight at ambient temperature and then extracted and analyzed. The mean extraction 

efficiency over the studied range was 98.7% for ____ {analyte}. The results for the RQL and 

the wet samplers were not included in the overall average. Wet samplers were prepared by 

sampling humid air (____ {RH} relative humidity at ____ {temp} °C) at {recommended sampling 

rate} for {recommended sampling time}. The data obtained are shown in Table 2.4. 

Table 2.4 

Extraction Efficiency of ____ {Analyte} from ____ {Active Sampler} 

level sample number

Η target μg per 1 2 3 4 mean 

concn sample 

0.1 21.0 99.8 97.5 

0.25 99.5 

0.5 

1.0 

1.5 

2.0 

RQL 

1.0 (wet) 

52.5 

105 

210 

315 

420 

2.08 

210 

103.5 

101.6 102.4 

101.9 101.8 

105.0 

92.8 

105.8 

95.8 

95.1 

99.6 

99.9 

99.6 

100.5 

95.8 

100.4 

97.7 

90.4 87.6 

104.3 94.7 

101.2 

100.0 

95.8 

100.2 

94.2 

97.7 

90.0 

100.5 

99.6 

100.6 

100.1 

99.9 

101.4 

96.0 

90.8 

99.8 

 

 2.5 Retention efficiency 

 Example: 

 Six ____ {samplers} were spiked with ____ μg of ____ {analyte} and then ____ L {1.25 times 

recommended volume} of humid air at ____ {RH} relative humidity and ____ {temp} ΕC was 

sampled. The samples were extracted and analyzed. The mean retention efficiency was 

 

24 Eide, M.; Simmons, M.; Hendricks, W. Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis, 2010. 

United States Department of Labor, Occupational Safety & Health Administration. 

http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf (accessed March 11, 2010).

56 of 59 
____%. There was ____% of ____ {analyte} found on the backup portion of the ____ 

{sampler}. {The amount spiked will be equivalent to two times the target concentration based 

on the recommended air sample volume}. The data obtained are shown in Table 2.5. 

Table 2.5 

Retention Efficiency of ____ {Analyte} 

sample number

section 1 2 3 4 5 6 mean 

front 

rear 

total 

99.1 

0 

99.1 

95.2 

1.2 

96.4 

97.3 

1.1 

98.4 

99.5 

0 

99.5 

99.6 

0 

99.6 

100.0 

0 

100.0 

98.4 

0.4 

98.8 

 

 2.6 Recommended air volume and sampling rate 

 Example: 

 Sample for up to ____min at ____mL/min for to collect TWA samples. 

 2.7 Sample stability 

 Example: 

 Twelve ____ {samplers} were each spiked 

with ____ μg of ____ {analyte} which is 

equivalent to ____ ppm (____ mg/m3

). 

The spiked samplers were used to sample 

____L {recommended air volume} of 

humid air at ____ {RH} relative humidity 

and ____ {temp} ΕC. The samples were 

then sealed and stored at ambient 

temperature. Three samples were analyzed immediately after preparation and three samples 

were analyzed every five days over the next 15 days. The data obtained are shown in Table 

2.7. 

3. Analytical Procedure {Refer to cited sections of format for Evaluated Methods for detail. Use 

paragraphs instead of using tertiary subsections} 

Adhere to the rules set down in your laboratory's Chemical Hygiene Plan25 (for instance: OSHA SLTC 

adheres to the rules set down in the OSHA SLTC Chemical Hygiene Plan). Avoid skin contact and 

inhalation of all chemicals and review all appropriate MSDSs before beginning the analytical 

procedure. Follow all applicable quality assurance practices established in your laboratory's internal 

quality system (for instance: OSHA SLTC follows the quality assurance practices established in the 

OSHA SLTC Quality Assurance Manual). 

 3.1 Apparatus {Section 3.1} 

Table 2.7 

Storage Test for ____ {Analyte}

 sample number

time (days) 1 2 3 

0 

5 

10 

15 

100.2 

99.8 

97.6 

93.7 

101.5 

100.8 

101.4 

91.8 

98.4 

100.5 

99.1 

95.2 

 

 3.2 Reagents {Section 3.2} 

 3.3 Standard preparation {Section 3.3} 

 3.4 Sample preparation {Section 3.4} 

 3.5 Analysis {Section 3.5} 

 3.6 Interferences (analytical) {Section 3.6} 

 

25 Occupational Exposure to Hazardous Chemicals in Laboratories. Code of Federal Regulations, Part 1910.1450, Title 29, 2003. 

.

57 of 59 
 3.7 Calculations {Section 3.7} 

4. Recommendations for Further Study 

58 of 59 
59 of 59 

PREPARATION OF WRITTEN REPORTS FOR ANALYTICAL STUDIES 

Follow the format of articles published in the ACS journal "Analytical Chemistry" as closely as possible 

and include sections on the following items: 

 1. Introduction (include purpose) 

 2. Experimental 

 3. Results and Discussion 

 4. References