California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 7 - General Industry Safety Orders › Group 16 - Control of Hazardous Substances › Article 110 - Regulated Carcinogens › Appendix B to Section 5217 - Sampling Strategy and Analytical Methods for Formaldehyde

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
To protect the health of employees, exposure
						  measurements must be unbiased and representative of employee exposure. The
						  proper measurement of employee exposure requires more than a token commitment
						  on the part of the employer. OSHA's mandatory requirements establish a
						  baseline; under the best of circumstances all questions regarding employee
						  exposure will be answered. Many employers, however, will wish to conduct more
						  extensive monitoring before undertaking expensive commitments, such as
						  engineering controls, to assure that the modifications are truly necessary. The
						  following sampling strategy, which was developed at NIOSH by Nelson A. Leidel,
						  Kenneth A. Busch, and Jeremiah R. Lynch and described in NIOSH publication No.
						  77-173 (Occupational Exposure Sampling Strategy Manual) will assist the
						  employer in developing a strategy for determining the exposure of his or her
						  employees.
There is no one correct way to determine employee
						  exposure. Obviously, measuring the exposure of every employee exposed to
						  formaldehyde will provide the most information on any given day. Where few
						  employees are exposed, this may be a practical solution. For most employers,
						  however, use of the following strategy will give just as much information at
						  less cost.
Exposure data collected on a single day will not
						  automatically guarantee the employer that his or her workplace is always in
						  compliance with the formaldehyde standard. This does not imply, however, that
						  it is impossible for an employer to be sure that his or her worksite is in
						  compliance with the standard. Indeed, a property designed sampling strategy
						  showing that all employees are exposed below the PELs, at least with a 95
						  percent certainty, is compelling evidence that the exposure limits are being
						  achieved provided that measurements are conducted using valid sampling strategy
						  and approved analytical methods.
There are two PELs, the TWA concentration and the STEL.
						  Most employers will find that one of these two limits is more critical in the
						  control of their operations, and OSHA expects that the employer will
						  concentrate monitoring efforts on the critical component. If the more difficult
						  exposure is controlled, this information, along with calculations to support
						  the assumptions, should be adequate to show that the other exposure limit is
						  also being achieved.
Sampling Strategy
Determination of the Need for Exposure
						  Measurements
The employer must determine whether employees may be
						  exposed to concentrations in excess of the action level. This determination
						  becomes the first step in an employee exposure monitoring program that
						  minimizes employer sampling burdens while providing adequate employee
						  protection. If employees may be exposed above the action level, the employer
						  must measure exposure. Otherwise, an objection determination that employee
						  exposure is low provides adequate evidence that exposure potential has been
						  examined.
The employer should examine all available relevant
						  information, e.g., insurance company and trade association data and information
						  from suppliers or exposure data collected from similar operations. The employer
						  may also use previously-conducted sampling including area monitoring. The
						  employer must make a determination relevant to each operation although this
						  need not be on a separate piece of paper. If the employer can demonstrate
						  conclusively that no employee is exposed above the action level or the STEL,
						  through the use of objective data, the employer need proceed no further on
						  employee exposure monitoring until such time that conditions have changed and
						  the determination is no longer valid.
If the employer cannot determine that employee exposure
						  is less than the action level and the STEL, employee exposure monitoring will
						  have to be conducted.
Workplace Material Survey
The primary purpose of a survey of raw material is to
						  determine if formaldehyde is being used in the work environment and if so, the
						  conditions under which formaldehyde is being used.
The first step is to tabulate all situations where
						  formaldehyde is used in a manner such that it may be released into the
						  workplace atmosphere or contaminate the skin. This information should be
						  available through analysis of company records and information on the MSDSs
						  available through provisions of this standard and the Hazard Communication
						  standard.
If there is an indication from materials handling
						  records and accompanying MSDSs that formaldehyde is being used in the following
						  types of processes or work operations, there may be a potential for releasing
						  formaldehyde into the workplace atmosphere:
(1) Any operation that involves grinding, sanding,
						  sawing, cutting, crushing, screening, sieving, or any other manipulation of
						  material that generates formaldehyde-bearing dust;
(2) Any processes where there have been employee
						  complaints or symptoms indicative of exposure to formaldehyde;
(3) Any liquid or spray process involving
						  formaldehyde;
(4) Any process that uses formaldehyde in preserved
						  tissue; and
(5) Any process that involves the heating of a
						  formaldehyde-bearing resin. Processes and work operations that use formaldehyde
						  in these manners will probably require further investigation at the worksite to
						  determine the extent of employee monitoring that should be conducted.
Workplace Observations
To this point, the only intention has been to provide
						  an indication as to the existence of potentially exposed employees. With this
						  information, a visit to the workplace is needed to observe work operations, to
						  identify potential health hazards, and to determine whether any employees may
						  be exposed to hazardous concentrations of formaldehyde.
In many circumstances, sources of formaldehyde can be
						  identified through the sense of smell. However, this method of detection should
						  be used with caution because of olfactory fatigue.
Employee location in relation to source of formaldehyde
						  is important in determining if an employee may be significantly exposed to
						  formaldehyde. In most instances, the closer a worker is to the source, the
						  higher the probability that a significant exposure will occur.
Other characteristics should be considered. Certain
						  high temperature operations give rise to higher evaporation rates. Locations of
						  open doors and windows provide natural ventilation that tend to dilute
						  formaldehyde emissions. General room ventilation also provides a measure of
						  control.
Calculation of Potential Exposure Concentrations
By knowing the ventilation rate in a workplace and the
						  quantity of formaldehyde generated, the employer may be able to determine by
						  calculation if the PELs might be exceeded. To account for poor mixing of
						  formaldehyde into the entire room, locations of fans and proximity of employees
						  to the work operation, the employer must include a safety factor. If an
						  employee is relatively close to a source, particularly if he or she is located
						  downwind, a safety factor of 100 may be necessary. For other situations, a
						  factor of 10 may be acceptable. If the employer can demonstrate through such
						  calculations that employee exposure does not exceed the action level or the
						  STEL, the employer may use this information as objective data to demonstrate
						  compliance with the standard.
Sampling Strategy
Once the employer determines that there is a
						  possibility of substantial employee exposure to formaldehyde, the employer is
						  obligated to measure employee exposure.
The next step is selection of a maximum risk employee.
						  When there are different processes where employees may be exposed to
						  formaldehyde, a maximum risk employee should be selected for each work
						  operation.
Selection of the maximum risk employee requires
						  professional judgment. The best procedure for selecting the maximum risk
						  employee is to observe employees and select the person closest to the source of
						  formaldehyde. Employee mobility may affect this selection; e.g., if the closest
						  employee is mobile in his tasks, he may not be the maximum risk employee. Air
						  movement patterns and differences in work habits will also affect selection of
						  the maximum risk employee.
When many employees perform essentially the same task,
						  a maximum risk employee cannot be selected. In this circumstance, it is
						  necessary to resort to random sampling of the group of workers. The objective
						  is to select a subgroup of adequate size so that there is a high probability
						  that the random sample will contain at least one worker with high exposure if
						  one exists. The number of persons in the group influences the number that need
						  to be sampled to ensure that at least one individual from the highest 10
						  percent exposure group is contained in the sample. For example, to have 90
						  percent confidence in the results, if the group size is 10, nine should be
						  sampled; for 50, only 18 need to be sampled.
If measurement shows exposure to formaldehyde at or
						  above the action level or the STEL, the employer needs to identify all other
						  employees who may be exposed at or above the action level or STEL and measure
						  or otherwise accurately characterize the exposure of these employees.
Whether representative monitoring or random sampling
						  are conducted, the purpose remains the same--to determine if the exposure of
						  any employee is above the action level. If the exposure of the most exposed
						  employee is less than the action level and the STEL, regardless of how the
						  employee is identified, then it is reasonable to assume that measurements of
						  exposure of the other employees in that operation would be below the action
						  level and the STEL.
Exposure Measurements
There is no "best" measurement strategy for all
						  situations. Some elements to consider in developing a strategy are:
(1) Availability and cost of sampling equipment,
(2) Availability and cost of analytic
						  facilities,
(3) Availability and cost of personnel to take
						  samples,
(4) Location of employees and work operations,
(5) Intraday and interday variations in the
						  process,
(6) Precision and accuracy of sampling and analytic
						  methods, and
(7) Number of samples needed.
Samples taken for determining compliance with STEL
						  differ from those that measure the TWA concentration in important ways. STEL
						  samples are best taken in a non-random fashion using all available knowledge
						  relating to the area, the individual, and the process to obtain samples during
						  periods of maximum expected concentrations. At least three measurements on a
						  shift are generally needed to spot gross errors or mistakes; however, only the
						  highest value represents the STEL.
If an operation remains constant throughout the
						  workshift, a much greater number of samples would need to be taken over the 32
						  discrete non-overlapping periods in an 8-hour workshift to verify compliance
						  with a STEL. If employee exposure is truly uniform throughout the workshift, an
						  employer in compliance with the 1 ppm TWA would be in compliance with the 2 ppm
						  STEL, and this determination can probably be made using objective data.
Need to Repeat the Monitoring Strategy
Interday and intraday fluctuations in employee exposure
						  are mostly influenced by the physical processes that generate formaldehyde and
						  the work habits of the employee. Hence, implant process variations influence
						  the employer's determination of whether or not additional controls need to be
						  imposed. Measurements that employee exposure is low on a day that is not
						  representative of worst conditions may not provide sufficient information to
						  determine whether or not additional engineering controls should be installed to
						  achieve the PELs.
The person responsible for conducting sampling must be
						  aware of systematic changes which will negate the validity of the sampling
						  results. Systematic changes in formaldehyde exposure concentration for an
						  employee can occur due to:
(1) The employee changing patterns of movement in the
						  workplace,
(2) Closing of plant doors and windows,
(3) Changes in ventilation from season to
						  season,
(4) Decreases in ventilation efficiency or abrupt
						  failure of engineering control equipment, and
(5) Changes in the production process or work habits of
						  the employee. Any of these changes, if they may result in additional exposure
						  that reaches the next level of action (i.e., 0.5 or 1.0 ppm as an 8-hr average
						  or 2 ppm over 15 minutes) require the employer to perform additional monitoring
						  to reassess employee exposure.
A number of methods are suitable for measuring employee
						  exposure to formaldehyde or for characterizing emissions within the worksite.
						  The preamble to this standard describes some methods that have been widely used
						  or subjected to validation testing. A detailed analytical procedure derived
						  from the OSHA Method 52 for acrolein and formaldehyde is presented below for
						  informational purposes.
Inclusion of OSHA's method in this appendix in no way
						  implies that it is the only acceptable way to measure employee exposure to
						  formaldehyde. Other methods that are free from significant interferences and
						  that can determine formaldehyde at the permissible exposure limits within z 25
						  percent of the "true" value at the 95 percent confidence level are also
						  acceptable. Where applicable, the method should also be capable of measuring
						  formaldehyde at the action level to z 35 percent of the "true" value with a 95
						  percent confidence level. OSHA encourages employers to choose methods that will
						  be best for their individual needs. The employer must exercise caution,
						  however, in choosing an appropriate method since some techniques suffer from
						  interferences that are likely to be present in workplaces of certain industry
						  sectors where formaldehyde is used.
OSHA's Analytical Laboratory Method
Method: No. 52
Matrix: Air
Target Concentration: 1 ppm (1.2
						  mg/m3)
Procedures: Air samples are collected by drawing known
						  volumes of air through sampling tubes containing XAD-2 adsorbent which have
						  been coated with 2-(hydroxymethyl) piperidine. The samples are desorbed with
						  toluene and then analyzed by gas chromatography using a nitrogen selective
						  detector.
Recommended Sampling Rate and Air Volumes: 0.1L/min and
						  24 L
Reliable Quantitation Limit: 16 ppb
						  (20ug/m3)
Standard Error of Estimate of the Target Concentration:
						  7.3%
Status of the Method: A sampling and analytical method
						  that has been subjected to the established evaluation procedures of the Organic
						  Methods of Evaluation Branch.
Date: March 1985
1. General Discussion
1.1 Background: The current OSHA method for collecting
						  acrolein vapor recommends the use of activated 13X molecular sieves. The
						  samples must be stored in an ice bath during and after sampling and also they
						  must be analyzed within 48 hours of collection. The current OSHA method for
						  collecting formaldehyde vapor recommends the use of bubblers containing 10%
						  methanol in water as the trapping solution.
This work was undertaken to resolve the sample
						  stability problems associated with acrolein and also to eliminate the need to
						  use bubblers to sample formaldehyde. A goal of this work was to develop and/or
						  to evaluate a common sampling and analytical procedure for acrolein and
						  formaldehyde.
NIOSH has developed independent methodologies for
						  acrolein and formaldehyde which recommend the use of reagent-coated adsorbent
						  tubes to collect the aldehydes as stable derivatives. The formaldehyde sampling
						  tubes contain Chromosorb 102 adsorbent coated with N-benzylethanolamine (BEA)
						  which reacts with formaldehyde vapor to form a stable oxazolidine compound. The
						  acrolein sampling tubes contain XAD-2 adsorbent coated with 2-(hydroxymethyl)
						  piperidine (2-HMP) which reacts with acrolein vapor to form a different, stable
						  oxazolidine derivative. Acrolein does not appear to react with BEA to give a
						  suitable reaction product. Therefore, the formaldehyde procedure cannot provide
						  a common method for both aldehydes. However, formaldehyde does react with 2-HMP
						  to form a very suitable reaction product. It is the quantitative reaction of
						  acrolein and formaldehyde with 2-HMP that provides the basis for this
						  evaluation.
This sampling and analytical procedure is very similar
						  to the method recommended by NIOSH for acrolein. Some changes in the NIOSH
						  methodology were necessary to permit the simultaneous determination of both
						  aldehydes and also to accommodate OSHA laboratory equipment and analytical
						  techniques.
1.2 Limit-defining parameters: The analyte air
						  concentrations reported in this method are based on the recommended air volume
						  for each analyte collected separately and a desorption volume of 1 mL. The
						  amounts are presented as acrolein and/or formaldehyde, even though the
						  derivatives are the actual species analyzed.
1.2.1 Detection limits of the analytical procedure: The
						  detection limit of the analytical procedure was 386 pg per injection for
						  formaldehyde. This was the amount of analyte which gave a peak whose height was
						  about five times the height of the peak given by the residual formaldehyde
						  derivative in a typical blank front section of the recommended sampling
						  tube.
1.2.2 Detection limits of the overall procedure: The
						  detection limits of the overall procedure were 482 ng per sample (16 ppb or 20
						  ug/m3 for formaldehyde). This was the amount of
						  analyte spiked on the sampling device which allowed recoveries approximately
						  equal to the detection limit of the analytical procedure.
1.2.3 Reliable quantitation limits: The reliable
						  quantitation limit was 482 ng per sample (16 ppb or 20
						  ug/m3) for formaldehyde. These were the smallest
						  amounts of analyte which could be quantitated within the limits of a recovery
						  of at least 75% and a precision (± 1.96 SD)of ± 25% or
						  better.
The reliable quantitation limit and detection limits
						  reported in the method are based upon optimization of the instrument for the
						  smallest possible amount of analyte. When the target concentration of an
						  analyte is exceptionally higher than these limits, they may not be attainable
						  at the routine operating parameters.
1.2.4 Sensitivity: The sensitivity of the analytical
						  procedure over concentration ranges representing 0.4 to 2 times the target
						  concentration, based on the recommended air volumes, was 7,589 area units per
						  ug/mL for formaldehyde. This value was determined from the slope of the
						  calibration curve. The sensitivity may vary with the particular instrument used
						  in the analysis.
1.2.5 Recovery: The recovery of formaldehyde from
						  samples used in an 18-day storage test remained above 92% when the samples were
						  stored at ambient temperature. These values were determined from regression
						  lines which were calculated from the storage data. The recovery of the analyte
						  from the collection device must be at least 75% following storage.
1.2.6 Precision (analytical method only): The pooled
						  coefficient of variation obtained from replicate determinations of analytical
						  standards over the range of 0.4 to 2 times the target concentration was 0.0052
						  for formaldehyde (section
						  4.3).
1.2.7 Precision (overall procedure): The precision at
						  the 95% confidence level for the ambient temperature storage tests was ±
						  14.3% for formaldehyde. These values each include an additional ± 5% for
						  sampling error. The overall procedure must provide results at the target
						  concentrations that are ± 25% at the 95% confidence level.
1.2.8 Reproducibility: Samples collected from
						  controlled test atmospheres and a draft copy of this procedure were given to a
						  chemist unassociated with this evaluation. The formaldehyde samples were
						  analyzed following 15 days storage. The average recovery was 96.3% and the
						  standard deviation was 1.7%.
1.3 Advantages:
1.3.1 The sampling and analytical procedures permit the
						  simultaneous determination of acrolein and formaldehyde.
1.3.2 Samples are stable following storage at ambient
						  temperature for at least 18 days.
1.4 Disadvantages: None.
2. Sampling Procedure
2.1 Apparatus:
2.1.1 Samples are collected by use of a personal
						  sampling pump that can be calibrated to within ± 5% of the recommended
						  0.1L/min sampling rate with the sampling tube in line.
2.1.2 Samples are collected with laboratory prepared
						  sampling tubes. The sampling tube is constructed of silane treated glass and is
						  about 8-cm long. The ID is 4 mm and the OD is 6 mm. One end of the tube is
						  tapered so that a glass wool end plug will hold the contents of the tube in
						  place during sampling. The other end of the sampling tube is open to its full
						  4-mm ID to facilitate packing of the tube. Both ends of the tube are
						  firepolished for safety. The tube is packed with a 75-mg backup section,
						  located nearest the tapered end and a 150-mg sampling section of pre-treated
						  XAD-2 adsorbent which has been coated with 2-HMP. The two sections of coated
						  adsorbent are separated and retained with small plugs of silanized glass wool.
						  Following packing, the sampling tubes are sealed with two 
						  7/32 inch
						  OD plastic end caps. Instructions for the pretreatment and the coating of XAD-2
						  adsorbent are presented in section
						  4 of this method.
2.1.3 Sampling tubes, similar to those recommended in
						  this method, are marketed by Supelco, Inc. These tubes were not available when
						  this work was initiated, therefore, they were not evaluated.
2.2 Reagents: None required.
2.3 Technique:
2.3.1 Properly label the sampling tube before sampling
						  and then remove the plastic end caps.
2.3.2 Attach the sampling tube to the pump using a
						  section of flexible plastic tubing such that the large, front section of the
						  sampling tube is exposed directly to the atmosphere. Do not place any tubing
						  ahead of the sampling tube. The sampling tube should be attached in the
						  worker's breathing zone in a vertical manner such that it does not impede work
						  performance.
2.3.3 After sampling for the appropriate time, remove
						  the sampling tube from the pump and then seal the tube with plastic end
						  caps.
2.3.4 Include at least one blank for each sampling set.
						  The blank should be handled in the same manner as the samples with the
						  exception that air is not drawn through it.
2.3.5 List any potential interferences on the sample
						  data sheet.
2.4 Breakthrough:
2.4.1 Breakthrough was defined as the relative amount
						  of analyte found on a backup sample in relation to the total amount of analyte
						  collected on the sampling train.
2.4.2 For formaldehyde collected from test atmospheres
						  containing 6 times the PEL, the average 5% breakthrough air volume was 41 L.
						  The sampling rate was 0.1L/min and the average mass of formaldehyde collected
						  was 250 ug.
2.5 Desorption Efficiency: No desorption efficiency
						  corrections are necessary to compute air sample results because analytical
						  standards are prepared using coated adsorbent. Desorption efficiencies were
						  determined, however, to investigate the recoveries of the analytes from the
						  sampling device. The average recovery over the range of 0.4 to 2 times the
						  target concentration, based on the recommended air volumes, was 96.2% for
						  formaldehyde. Desorption efficiencies were essentially constant over the ranges
						  studied.
2.6 Recommended Air Volume and Sampling Rate:
2.6.1 The recommended air volume for formaldehyde is 24
						  L.
2.6.2 The recommended sampling rate is 0.1L/min.
2.7 Interferences:
2.7.1 Any collected substance that is capable of
						  reacting 2-HMP and thereby depleting the derivatizing agent is a potential
						  interference. Chemicals which contain a carbonyl group, such as acetone, may be
						  capable of reacting with 2-HMP.
2.7.2 There are no other known interferences to the
						  sampling method.
2.8 Safety Precautions:
2.8.1 Attach the sampling equipment to the worker in
						  such a manner that it will not interfere with work performance or
						  safety.
2.8.2 Follow all safety practices that apply to the
						  work area being sampled.
3. Analytical Procedure
3.1 Apparatus:
3.1.1 A gas chromatograph (GC), equipped with a
						  nitrogen selective detector. A Hewlett-Packard Model 5840A GC fitted with a
						  nitrogen-phosphorus flame ionization detector (NPD) was used for this
						  evaluation. Injections were performed using a Hewlett-Packard Model 7671A
						  automatic sampler.
3.1.2 A GC column capable of resolving the analytes
						  from any interference. A 6 ft x ¼ in OD (2mm ID) glass GC column
						  containing 10% UCON 50-HB-5100 + 2% KOH on 80/100 mesh Chromosorb W-AW was used
						  for the evaluation. Injections were performed on-column.
3.1.3 Vials, glass 2-mL with Teflon-lined caps.
3.1.4 Volumetric flasks, pipets, and syringes for
						  preparing standards, making dilutions, and performing injections.
3.2 Reagents:
3.2.1 Toluene and dimethylformamide. Burdick and
						  Jackson solvents were used in this evaluation.
3.2.2 Helium, hydrogen, and air, GC grade.
3.2.3 Formaldehyde, 37% by weight, in water. Aldrich
						  Chemical, ACS Reagent Grade formaldehyde was used in this evaluation.
3.2.4 Amberlite XAD-2 adsorbent coated with
						  2-(hydrosymethyl-piperidine (2-HMP), 10% by weight (section
						  4).
3.2.5 Desorbing solution with internal standard. This
						  solution was prepared by adding 20 uL of dimethylformamide to 100 mL of
						  toluene.
3.3 Standards preparation:
3.3.1 Formaldehyde: Prepare stock standards by diluting
						  known volumes of 37% formaldehyde solution with methanol. A procedure to
						  determine the formaldehyde content of these standards is presented in section
						  4. A standard containing 7.7 mg/mL
						  formaldehyde was prepared by diluting 1 mL of the 37% reagent to 50 mL with
						  methanol.
3.3.2 It is recommended that analytical standards be
						  prepared about 16 hours before the air samples are to be analyzed in order to
						  ensure the complete reaction of the analytes with 2-HMP. However, rate studies
						  have shown the reaction to be greater than 95% complete after 4 hours.
						  Therefore, one or two standards can be analyzed after this reduced time if
						  sample results are outside the concentration range of the prepared
						  standards.
3.3.3 Place 150-mg portions of coated XAD-2 adsorbent,
						  from the same lot number as used to collect the air samples, into each of
						  several glass 2-mL vials. Seal each vial with a Teflon-lined cap.
3.3.4 Prepare fresh analytical standards each day by
						  injecting appropriate amounts of the diluted analyte directly onto 150-mg
						  portions of coated adsorbent. It is permissible to inject both acrolein and
						  formaldehyde on the same adsorbent portion. Allow the standards to stand at
						  room temperature. A standard, approximately the target levels, was prepared by
						  injecting 11 uL of the acrolein and 12 uL of the formaldehyde stock standards
						  onto a single coated XAD-2 adsorbent portion.
3.3.5 Prepare a sufficient number of standards to
						  generate the calibration curves. Analytical standard concentrations should
						  bracket sample concentrations. Thus, if samples are not in the concentration
						  range of the prepared standards, additional standards must be prepared to
						  determine detector response.
3.3.7 Desorb the standards in the same manner as the
						  samples following the 16-hour reaction time.
3.4 Sample preparation:
3.4.1 Transfer the 150-mg section of the sampling tube
						  to a 2-mL vial. Place the 75-mg section in a separate vial. If the glass wool
						  plugs contain a significant number of adsorbent beads, place them with the
						  appropriate sampling tube section. Discard the glass wool plugs if they do not
						  contain a significant number of adsorbent beads.
3.4.2 Add 1 mL of desorbing solution to each
						  vial.
3.4.3 Seal the vials with Teflon-lined caps and then
						  allow them to desorb for one hour. Shake the vials by hand with vigorous force
						  several times during the desorption time.
3.4.4 Save the used sampling tubes to be cleaned and
						  recycled.
3.5 Analysis:
3.5.1 GC Conditions Column Temperature:
Bi-level temperature program-First level: 100 to
						  1405°C at 45°C/min following completion of the first level.
Second level: 140 to 180°C at 20°C/min
						  following completion of the first level.
Isothermal period: Hold column at 180°C until the
						  recorder pen returns to baseline (usually about 25 min after injection).
Injector temperature: 180°C
Helium flow rate: 30 mL/min (detector response will be
						  reduced if nitrogen is substituted for helium carrier gas).
Injection volume: 0.8 uL GC column: Six-ft x ¼
						  -in OD (2 mm ID) glass
GC column containing 10% UCON 50-HB-5100-2% KOH on
						  80/100 Chromosorb W-AW.
NPD conditions:
Hydrogen flow rate: 3 mL/min
Air flow rate: 50 mL/min
Detector temperature: 275°C
3.5.2 Chromatogram: For an example of a typical
						  chromatogram, see Figure 4.11 in OSHA Method 52.
3.5.3 Use a suitable method, such as electronic
						  integration, to measure detector response.
3.5.4 Use an internal standard method to prepare the
						  calibration curve with several standard solutions of different concentrations.
						  Prepare the calibration curve daily. Program the integrator to report results
						  in ug/mL.
3.5.5 Bracket sample concentrations with
						  standards.
3.6 Interferences (Analytical).
3.6.1 Any compound with the same general retention time
						  as the analytes and which also gives a detector response is a potential
						  interference. Possible interferences should be reported to the laboratory with
						  submitted samples by the industrial hygienist.
3.6.2 GC parameters (temperature, column, etc.) may be
						  changed to circumvent interferences.
3.6.3 A useful means of structure designation is GC/MS.
						  It is recommended this procedure be used to confirm samples whenever
						  possible.
3.6.4 The coated adsorbent usually contains a very
						  small amount of residual formaldehyde derivative (section
						  4.8).
3.7 Calculations:
3.7.1 Results are obtained by use of calibration
						  curves. Calibration curves are prepared by plotting detector response against
						  concentration for each standard. The best line through the data points is
						  determined by curve fitting.
3.7.2 The concentration in ug/mL for a particular
						  sample is determined by comparing its detector response to the calibration
						  curve. If either of the analytes is found on the backup section, it is added to
						  the amount found on the front section. Blank corrections should be performed
						  before adding the results together.
3.7.3 The acrolein and/or formaldehyde air
						  concentration can be expressed using the following equation:
mg/m3 = (A) (B)/C
where A = ug/mL from 3.7.2, B = desorption volume, and
						  C = L of air sampled.
No desorption efficiency corrections are
						  required.
3.7.4 The following equation can be used to convert
						  result in mg/m3 to ppm. ppm =
						  (mg/m3) (24.45)/MW
where mg/m3 = result from
						  3.7.3, 24.45 = molar volume of an ideal gas at 760 mm Hg and 25°C, MW =
						  molecular weight (30.0).
4. Backup Data
4.1 Backup data on detection limits, reliable
						  quantitation limits, sensitivity and precision of the analytical method,
						  breakthrough, desorption efficiency, storage, reproducibility, and generation
						  of test atmospheres are available in OSHA Method 52, developed by the Organics
						  Methods Evaluation Branch, OSHA Analytical Laboratory, Salt Lake City,
						  Utah.
4.2 Procedure to Coat XAD-2 Adsorbent with
						  2-HMP:
4.2.1 Apparatus: Soxhlet extraction apparatus, rotary
						  evaporation apparatus, vacuum desiccator, 1-L vacuum flask, 1-L round-bottomed
						  evaporative flask, 1-L Erlenmeyer flask, 250-mL Buchner funnel with a coarse
						  fritted disc, etc.
4.2.2 Reagents:
4.2.2.1 Methanol, isooctane, and toluene.
4.2.2.2 (Hydroxymethyl) piperidine.
4.2.2.3 Amberlite XAD-2 non-ionic polymeric adsorbent,
						  20 to 60 mesh, Aldrich Chemical XAD-2 was used in this evaluation.
4.2.3 Procedure: Weigh 125 g of crude XAD-2 adsorbent
						  into a 1-L Erlenmeyer flask. Add about 200 mL of water to the flask and then
						  swirl the mixture to wash the adsorbent. Discard any adsorbent that floats to
						  the top of the water and then filter the mixture using a fritted Buchner
						  funnel. Air dry the adsorbent for 2 minutes. Transfer the adsorbent back to the
						  Erlenmeyer flask and then add about 200 mL of methanol to the flask. Swirl and
						  then filter the mixture as before. Transfer the washed adsorbent to a 1-L
						  round-bottomed evaporative flask, add 13 g of 2-HMP and then 200 mL of
						  methanol, swirl the mixture and then allow it to stand for one hour. Remove the
						  methanol at about 405C and reduced pressure using a rotary evaporation
						  apparatus. Transfer the coated adsorbent to a suitable container and store it
						  in a vacuum desiccator at room temperature overnight. Transfer the coated
						  adsorbent to a Soxhlet extractor and then extract the material with toluene for
						  about 24 hours. Discard the contaminated toluene, add methanol in its place,
						  and then continue the Soxhlet extraction for an additional 4 hours. Transfer
						  the adsorbent to a weighted 1-L round-bottom evaporative flask and remove the
						  methanol using the rotary evaporation apparatus. Determine the weight of the
						  adsorbent and then add an amount of 2-HMP, which is 10% by weight of the
						  adsorbent. Add 200 mL of methanol and then swirl the mixture. Allow the mixture
						  to stand for one hour. Remove the methanol by rotary evaporation. Transfer the
						  coated adsorbent to a suitable container and store it in a vacuum desiccator
						  until all traces of solvents are gone. Typically, this will take 2-3 days. The
						  coated adsorbent should be protected from contamination. XAD-2 adsorbent
						  treated in this manner will probably not contain residual acrolein derivative.
						  However, this adsorbent will often contain residual formaldehyde derivative
						  levels of about 0.1 ug per 150 mg of adsorbent. If the blank values for a batch
						  of coated adsorbent are too high, then the batch should be returned to the
						  Soxhlet extractor, extracted with toluene again, and then recoated. This
						  process can be repeated until the desired blank levels are attained.
The coated adsorbent is now ready to be packed into
						  sampling tubes. The sampling tubes should be stored in a sealed container to
						  prevent contamination. Sampling tubes should be stored in the dark at room
						  temperature. The sampling tubes should be segregated by coated adsorbent lot
						  number. A sufficient amount of each lot number of coated adsorbent should be
						  retained to prepare analytical standards for use with air samples from that lot
						  number.
4.3 A Procedure to Determine Formaldehyde by Acid
						  Titration: Standardize the 0.1 N HC1 solution using sodium carbonate and methyl
						  orange indicator.
Place 50 mL of 0.1 M sodium sulfite and three drops of
						  thymophthalein indicator into a 250-mL Erlenmeyer flask. Titrate the contents
						  of the flask to a colorless endpoint with 0.1 N HC1 (usually one or two drops
						  is sufficient). Transfer 10 mL of the formaldehyde/methanol solution (prepared
						  in 3.3.1) into the same flask and titrate the mixture with 0.1 N HC1. again, to
						  a colorless endpoint. The formaldehyde concentration of the standard may be
						  calculated by the following equation:
Formal-
acid titer x acid
dehyde, =
normality x 30.0
mg/mL
mL of sample
This method is based on the quantitative liberation of
						  sodium hydroxide when formaldehyde reacts with sodium sulfite to form the
						  formaldehyde-bisulfite addition product. The volume of sample may be varied
						  depending on the formaldehyde content but the solution to be titrated must
						  contain excess sodium sulfite. Formaldehyde solutions containing substantial
						  amounts of acid or base must be neutralized before analysis.