524.3-1

 EPA Document # EPA 815-B-09-009 

METHOD 524.3 MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN 

WATER BY CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS 

SPECTROMETRY 

Version 1.0 

June 2009 

B. Prakash, A. D. Zaffiro, and M. Zimmerman (Shaw Environmental, Inc.) 

D. J. Munch (U.S. EPA, Office of Ground Water and Drinking Water) 

B. V. Pepich (U.S. EPA, Region 10 Laboratory) 

TECHNICAL SUPPORT CENTER 

OFFICE OF GROUND WATER AND DRINKING WATER 

U. S. ENVIRONMENTAL PROTECTION AGENCY 

CINCINNATI, OHIO 45268 
 

524.3-2

METHOD 524.3 

MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY CAPILLARY 

COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY 

1. SCOPE AND APPLICATION

1.1 This is a gas chromatography/mass spectrometry (GC/MS) method for the determination of 

purgeable organic compounds in finished drinking waters. Discontinuous scanning modes 

such as selected ion monitoring (SIM) and selected ion storage (SIS) are permitted for 

determining selected analytes that are monitored at levels too low for the full scan detection 

mode. Precision and accuracy data have been generated for the method analytes in reagent 

water, drinking water from a groundwater source, and drinking water from a surface water 

source. The single laboratory Lowest Concentration Minimum Reporting Level (LCMRL) 

has also been determined in reagent water. The following compounds can be determined 

using this method: 

Analyte

Chemical Abstract Services Registry 

Number (CASRN)

1,1,1,2-tetrachloroethane 630-20-6 

1,1,1-trichloroethane 71-55-6 

1,1,2,2-tetrachloroethane 79-34-5 

1,1,2-trichloroethane 79-00-5 

1,1-dichloroethane 75-34-3 

1,1-dichloroethene 75-35-4 

1,1-dichloropropene 563-58-6 

1,2,3-trichlorobenzene 87-61-6 

1,2,3-trichloropropane 96-18-4 

1,2,4-trichlorobenzene 120-82-1 

1,2,4-trimethylbenzene 95-63-6 

1,2-dibromo-3-chloropropane 96-12-8 

1,2-dibromoethane 106-93-4 

1,2-dichlorobenzene 95-50-1 

1,2-dichloroethane 107-06-2 

1,2-dichloropropane 78-87-5 

1,3,5-trimethylbenzene 108-67-8 

1,3-butadiene a

 106-99-0 

1,3-dichlorobenzene 541-73-1 

1,3-dichloropropane 142-28-9 

1,4-dichlorobenzene 106-46-7 

1-chlorobutane 109-69-3 

2-chlorotoluene 95-49-8 

4-chlorotoluene 106-43-4 

4-isopropyltoluene 99-87-6 
 

524.3-3

Analyte

Chemical Abstract Services Registry 

Number (CASRN)

allyl chloride 107-05-1 

benzene 71-43-2 

bromobenzene 108-86-1 

bromochloromethane 74-97-5 

bromodichloromethane 75-27-4 

bromoform 75-25-2 

bromomethane 74-83-9 

carbon disulfide 75-15-0 

carbon tetrachloride 56-23-5 

chlorobenzene 108-90-7 

chlorodifluoromethane a 75-45-6 

chloroform 67-66-3 

chloromethane 74-87-3 

cis-1,2-dichloroethene 156-59-2 

cis-1,3-dichloropropene 10061-01-5 

dibromochloromethane 124-48-1 

dibromomethane 74-95-3 

dichlorodifluoromethane 75-71-8 

diethyl ether 60-29-7 

diisopropyl ether (DIPE) b

 108-20-3 

ethyl methacrylate 97-63-2 

ethylbenzene 100-41-4 

hexachlorobutadiene 87-68-3 

hexachloroethane 67-72-1 

isopropylbenzene 98-82-8 

methyl acetate c 79-20-9 

methyl iodide 74-88-4 

methylene chloride 75-09-2 

methyl-t-butyl ether (MtBE) 1634-04-4 

m-xylene 108-38-3 

naphthalene 91-20-3 

n-butylbenzene 104-51-8 

n-propylbenzene 103-65-1 

o-xylene 95-47-6 

pentachloroethane 76-01-7 

p-xylene 106-42-3 

sec-butylbenzene 135-98-8 

styrene 100-42-5 

t-amyl ethyl ether (TAEE) b

 919-94-8 

t-amyl methyl ether (TAME) b 994-05-8 

t-butyl alcohol (TBA) b 75-65-0 
 

524.3-4

Analyte

Chemical Abstract Services Registry 

Number (CASRN)

t-butyl ethyl ether (ETBE) b

 637-92-3 

t-butylbenzene 98-06-6 

tetrachloroethene 127-18-4 

tetrahydrofuran 109-99-9 

toluene 108-88-3 

trans-1,2-dichloroethene 156-60-5 

trans-1,3-dichloropropene 10061-02-6 

trichloroethene 79-01-6 

trichlorofluoromethane 75-69-4 

vinyl chloride 75-01-4 

a

 New in revision 524.3: emerging contaminant of interest 

b

 New in revision 524.3: reformulated gasoline additive 

c

 New in revision 524.3: potential breakdown product of MtBE 

1.2 The mass spectrometry conditions described in this method were developed using a gas 

chromatograph (GC) interfaced to a quadrupole mass spectrometer (MS). 

1.3 The single laboratory LCMRL is the lowest spiking concentration such that the probability of 

spike recovery in the 50% to 150% range is at least 99%. Single laboratory LCMRLs for the 

analytes in this method ranged from 0.030 to 0.35 microgram per liter (μg/L) in the full scan 

mode, and are listed in Table 6. Single laboratory LCMRLs were also determined for selected 

analytes in the selected ion monitoring (SIM) mode (Table 10). The procedure used to 

determine the LCMRL is described elsewhere.1

1.4 Laboratories using this method are not required to determine LCMRLs, but they must 

demonstrate that the minimum reporting level (MRL) for each analyte meets the requirements 

described in Section 9.2.4. 

1.5 Detection limit (DL) is defined as the statistically calculated minimum concentration that can 

be measured with 99% confidence that the reported value is greater than zero.2

 The DL is 

dependent on sample matrix, fortification concentration, and instrument performance. Determining the DL for analytes in this method is optional (Sect. 9.2.6). DLs for method analytes 

fortified into reagent water ranged from 0.0077 to 0.14 μg/L in the full scan mode. These 

values are presented in Table 6. DLs were also determined for selected analytes in SIM mode 

(Table 10). 

1.6 This method is intended for use by analysts skilled in the technique of purge-and-trap 

concentration, the operation of GC/MS instrumentation, and the interpretation of the 

associated data. 

1.7 METHOD FLEXIBILITY – In recognition of technological advances in analytical 

instrumentation and techniques, the laboratory is permitted to modify purge-and-trap 

parameters and the GC/MS conditions. Because the purge-and-trap technique has a 

significant number of analyst-chosen parameters, and because it employs a procedural 
 

524.3-5

calibration, the authors have determined an acceptable range of purge-and-trap conditions that 

may be used (Sect. 9.1) and a means by which to evaluate method modifications (Sect. 9.4). 

Changes may not be made to sample collection and preservation (Sect. 8) or to the 

quality control (QC) requirements (Sect. 9). Modifications that are introduced solely in the 

interest of reducing cost or sample processing time, but result in poorer method performance, 

may not be used. The option to operate the MS in SIM or SIS mode is restricted to analytes 

that cannot be effectively analyzed in full scan mode for compounds of interest, e.g., 1,2-

dibromoethane and 1,2-dibromo-3-chloropropane. The SIM detection mode should not be 

used to enhance analyte signal for instrumentation that is not properly optimized and 

maintained. Trihalomethanes (THMs) and other commonly occurring contaminants in 

drinking water must be analyzed in the full scan detection mode. In all cases where method 

modifications are proposed, the analyst must perform the procedures outlined in the Initial 

Demonstration of Capability (IDC, Sect. 9.2), verify that all QC acceptance criteria in this 

method (Tables 15 and 16) are met, and verify method performance in real sample matrices 

(Sect. 9.4.4). 

NOTE: This description of method flexibility is an abbreviated summation. Additional 

specific detail is provided throughout the method, which supersedes the above general 

guidance. 

2. SUMMARY OF METHOD

Headspace-free samples are collected in amber, glass vials with polytetrafluoroethylene (PTFE)-

faced septa. Samples are dechlorinated with ascorbic acid and the pH is adjusted with maleic acid. 

A 5.0-milliliter (mL) aliquot of the sample is transferred to a glass sparging vessel along with 

appropriate amounts of internal standard and quality control compounds. The method analytes are 

purged from the water using helium and trapped on a sorbent material. After purging, the trap may 

be dry purged for a short period to remove water. Additional water management techniques may be 

applied. The trap is heated and backflushed with helium to transfer the analytes directly into a gas 

chromatographic inlet. The inlet is operated in the split mode in order to achieve the desired desorb 

flow rates and further reduce water transmission. Analytes are transferred onto a capillary GC 

column, which is temperature programmed to optimize the separation of method analytes. 

Compounds eluting from the GC are directed into a mass spectrometer for detection and 

quantitation. The method analytes are identified by comparing the acquired mass spectra and 

retention times to reference spectra and retention times for calibration standards acquired under 

identical GC/MS conditions. The concentration of each analyte is calculated using the internal 

standard technique and response curves obtained via procedural calibration (Sect. 3.18). 

3. DEFINITIONS

3.1 ANALYSIS BATCH – A sequence of samples, analyzed within a 24-hour period, including 

no more than 20 field samples. Each Analysis Batch must also include all required QC 

samples, which do not contribute to the maximum field sample total of 20. The required QC 

samples include: 

Laboratory Reagent Blank (LRB), 

 Continuing Calibration Check (CCC) Standards, 

Laboratory Fortified Sample Matrix (LFSM), and 

Laboratory Fortified Sample Matrix Duplicate or Field Duplicate (LFSMD or FD). 
 

524.3-6

3.2 CALIBRATION STANDARD – An aqueous solution of the method analytes prepared from 

the Primary Dilution Standard solution. The calibration standard solutions are used to 

calibrate the instrument response with respect to analyte concentration. 

3.3 CONTINUING CALIBRATION CHECK (CCC) – A calibration standard containing the 

method analytes, internal standards and surrogate analytes, which is analyzed periodically to 

verify the accuracy of the existing calibration. 

3.4 DESORB FLOW RATE – The rate at which gas is passed through the sorbent trap during the 

desorb cycle. The desorb flow rate is approximately equal to the total flow rate through the 

GC inlet (mL/min). 

3.5 DETECTION LIMIT (DL) – The minimum concentration of an analyte that can be identified, 

measured, and reported with 99% confidence that the analyte concentration is greater than 

zero. This is a statistical determination (Sect. 9.2.6), and accurate quantitation is not expected 

at this level. 

3.6 DRY PURGE VOLUME – The total volume of purge gas (mL) bypassing the sparging vessel 

and passing through the sorbent trap during the dry purge cycle as a moisture control measure. 

3.7 FIELD DUPLICATE (FD) – Separate samples collected at the same time, shipped and stored 

under identical conditions. Method precision, including the contribution from sample 

collection procedures, is estimated from the analysis of FDs. For the purposes of this method, 

Field Duplicates are necessary to conduct repeat analyses if the original field sample is lost, or 

to conduct repeat analyses in the case of QC failures associated with the analysis of the 

original field sample. Field Duplicates are used to prepare Laboratory Fortified Sample 

Matrix (Sect. 3.11) and Laboratory Fortified Sample Matrix Duplicate (Sect. 3.12) QC 

samples. 

3.8 FIELD REAGENT BLANK (FRB) – An aliquot of reagent water that is placed in a sample 

container in the laboratory and treated as a sample in all respects, including shipment to the 

sampling site, exposure to sampling site conditions, storage, preservation, and all analytical 

procedures. The purpose of the FRB is to determine if method analytes or other interferences 

are introduced into the samples during transport and storage. 

3.9 INTERNAL STANDARD (IS) – A pure compound added to all standard solutions, field 

samples and QC samples in a known amount. Each internal standard is assigned to a specific 

analyte or multiple analytes, and is used to measure relative response. 

3.10 LABORATORY FORTIFIED BLANK (LFB) – An aliquot of reagent water to which known 

quantities of the method analytes are added. The LFB is analyzed in the same manner as a 

sample, including the preservation procedures in Section 8. The LFB is used during the IDC 

to verify method performance for precision and accuracy. 

3.11 LABORATORY FORTIFIED SAMPLE MATRIX (LFSM) – A Field Duplicate to which 

known quantities of the method analytes are added. The LFSM is processed and analyzed as a 

sample, and its purpose is to determine whether the sample matrix contributes bias to the 
 

524.3-7

analytical results. For this method, separate field samples are required for preparing fortified 

matrix so that sampling error is included in the accuracy estimate. 

3.12 LABORATORY FORTIFIED SAMPLE MATRIX DUPLICATE (LFSMD) – A second Field 

Duplicate, of the same sample used to prepare the LFSM, which is fortified identically to the 

LFSM. The LFSMD is used instead of the Field Duplicate to assess method precision and 

accuracy when the occurrence of the method analytes is infrequent. For this method, separate 

field samples are required for preparing fortified matrix so that sampling error is included in 

the precision estimate. 

3.13 LABORATORY REAGENT BLANK (LRB) – An aliquot of reagent water containing the 

preservatives, internal standards and surrogate analytes. The LRB is used to determine if the 

method analytes or interferences are introduced from the laboratory environment, the reagents 

or glassware. The LRB is also used to test for cross contamination in the purge-and-trap 

system. 

3.14 LOWEST CONCENTRATION MINIMUM REPORTING LEVEL (LCMRL) – The single 

laboratory LCMRL is the lowest spiking concentration such that the probability of spike 

recovery in the 50% to 150% range is at least 99%.1

3.15 MATERIAL SAFETY DATA SHEETS (MSDS) – Written information provided by vendors 

concerning a chemical’s toxicity, health hazards, physical properties, fire and reactivity data, 

storage instructions, spill response procedures, and handling precautions. 

3.16 MINIMUM REPORTING LEVEL (MRL) – The minimum concentration that can be reported 

by a laboratory as a quantified value for the method analyte in a sample following analysis. 

This concentration must meet the criteria defined in Section 9.2.4 and must be no lower than 

the concentration of the lowest calibration standard for each method analyte. 

3.17 PRIMARY DILUTION STANDARD (PDS) – A solution containing the method analytes (or 

internal standards and surrogate analytes) prepared in the laboratory from Stock Standard 

Solutions and diluted as needed to prepare calibration standards and sample fortification 

solutions. 

3.18 PROCEDURAL CALIBRATION – A calibration technique in which calibration standards are 

processed through the entire method, including sample preparation, addition of preservatives, 

extraction and concentration. 

3.19 PURGE FLOW RATE – The rate (mL/min) that the purge gas flows through the sparging 

vessel during the purge cycle. 

3.20 PURGE VOLUME – The total volume of purge gas (mL) that flows through the sparging 

vessel during the purge cycle. 

3.21 QUALITY CONTROL SAMPLE (QCS) – A solution containing the method analytes at a 

known concentration that is obtained from a source external to the laboratory and different 

from the source of calibration standards. The purpose of the QCS is to verify the accuracy of 

the primary calibration standards. 
 

524.3-8

3.22 REAGENT WATER – Purified water that does not contain any measurable quantity of the 

method analytes or interfering compounds at or above 1⁄2 the MRL. 

3.23 STOCK STANDARD SOLUTION (SSS) – A concentrated solution containing one or more 

of the method analytes that is prepared in the laboratory using assayed reference materials or 

purchased from a reputable commercial source, so that the concentration and purity of 

analytes are traceable to certificates of analysis. 

3.24 SURROGATE ANALYTE – A pure analyte which is extremely unlikely to be found in any 

sample, and which is added to a sample aliquot in a known amount before analysis. 

Surrogates are measured with the same procedures used to measure other sample components. 

Because surrogates are present in every sample, they provide a means of assessing method 

performance for a specific purge-and-trap analysis cycle. 

4. INTERFERENCES

4.1 SAMPLE CONTAINERS, SHIPPING AND STORAGE – Volatile organic compounds 

(VOCs) present in ambient air, shipping containers, and in the laboratory environment may 

permeate the PTFE-lined septa of the sample vials or be present at high concentrations in the 

headspace of the vial—especially if the vials were prepared in a laboratory. Contamination 

from these sources is assessed by analyzing Field Reagent Blanks as described in Section 

9.3.9. 

4.2 PURGE AND TRAP SYSTEM – Commercially available purge-and-trap concentrators and 

autosamplers have complex sample paths that are subject to cross contamination, which is 

commonly referred to as “carryover.” Carryover is controlled by minimizing the transfer line 

length from the autosampler to the sparging vessel and optimizing the bake cycle and rinse 

cycle parameters. The potential for carryover in the purge-and-trap system is evaluated during 

the Initial Demonstration of Capability by analyzing the highest concentration calibration 

standard followed by an LRB. 

4.3 REAGENTS – All laboratory reagents must be routinely demonstrated to be free from 

interferences under the conditions of the analysis. This may be accomplished by analyzing 

LRBs and meeting the acceptance criterion as described in Section 9.3.1. 

4.3.1 REAGENT WATER – Analysts may observe common laboratory contaminants, such 

as methylene chloride, in reagent water. Boiling and/or sparging reagent water with 

nitrogen is recommended. If possible, prepare aqueous standards and blanks in a 

laboratory environment isolated from ambient sources of VOCs. 

4.3.2 METHANOL – Traces of ketones, methylene chloride, and other organic solvents 

could be present in methanol. Purge-and-trap-grade methanol is prescribed for use 

with this method. 

4.3.3 PRESERVATION REAGENTS – The potential exists for trace-level organic 

contaminants in the preservation reagents. Interferences from these sources must be 

monitored by analysis of LRBs when new lots of reagents are acquired. 
 

524.3-9

4.3.4 SORBENT MATERIALS – Sorbent traps must be carefully evaluated because some 

traps, when heated, have been reported to produce small amounts of VOCs, 

particularly with extended use. For example, toluene may be detected the first time a 

trap is desorbed during a work shift. For this reason, a short bake cycle prior to 

beginning an analysis sequence is recommended. 

4.3.5 PURGE GAS SUPPLY – Helium used to purge samples is a potential source of 

common laboratory contaminants. Trace VOCs in the purge gas, supply lines, or 

permeating from the gas supply system—including the regulator—will concentrate on 

the sorbent trap. High-purity gas supplies and high-purity gas regulators are 

recommended to minimize contamination from these sources. Purge gas filters 

should be regenerated or replaced at the intervals specified by the manufacturers. 

4.4 MATRIX INTERFERENCES – Matrix interferences are caused by contaminants that are 

present in the sample. The extent of matrix interferences will vary considerably from source 

to source depending upon the nature of the water. The analysis of Laboratory Fortified 

Sample Matrix (Sect. 9.3.7) provides evidence for the presence (or absence) of matrix effects. 

5. SAFETY

5.1 The toxicity or carcinogenicity of each reagent used in this method has not been precisely 

defined. Each chemical should be treated as a potential health hazard and exposure to these 

chemicals should be minimized. Each laboratory is responsible for maintaining an awareness 

of OSHA regulations regarding safe handling of chemicals used in this method.3 The OSHA 

laboratory standards can be found on line at 

http://www.osha.gov/SLTC/laboratories/standards.html. A reference file of MSDSs should be 

made available to all personnel involved in the chemical analysis. 

5.2 Pure standard materials and Stock Standard Solutions of the method compounds should be 

handled with suitable protection for skin, eyes, etc.4

6. EQUIPMENT AND SUPPLIES 

References to specific brands or catalog numbers are included as examples only and do not imply 

endorsement of the product. These references do not preclude the use of other vendors or supplies. 

6.1 SAMPLE CONTAINERS – Clean, amber volatile organic analysis (VOA) vials fitted with 

PTFE-faced silicone septa and polypropylene screw caps (I-Chem Cat. No. S146–0040 or 

equivalent). Prior to reuse, wash vials and septa (if not punctured) with detergent and rinse 

with tap and distilled water. Place vials in a 105 degrees Centigrade (°C) oven for one hour, 

then allow to cool in an area isolated from ambient sources of VOCs. 

6.2 MICRO SYRINGES – Suggested sizes include 2.0, 5.0, 10, and 25 μL. 

6.3 PURGE-AND-TRAP SYRINGES – 5-mL glass syringes with PTFE Luer-Lok (Hamilton 

Model No. 1005 TLL or equivalent) for manual loading of samples into a sparging vessel. 

6.4 SYRINGE VALVE – two-position syringe valves with Luer ends (Supelco Cat. No. 20926 or 

equivalent) for use sealing purge-and-trap syringes (Sect. 6.3). 
 

524.3-10

6.5 VOLUMETRIC FLASKS – Class A, suggested sizes include 50, 100, and 200 mL for 

preparation of calibration standards. 

6.6 ANALYTICAL BALANCE – Capable of weighing to the nearest 0.0001 gram (g). 

6.7 MICRO-REACTION VESSEL – 0.3-, 1.0-, 2.0-, 5.0-mL sizes (Supelco Cat Nos. 33291, 

33293, 33295, 33299, or equivalent) equipped with Mininert Valves [Supelco Cat No. 33301 

(15 millimeter (mm) for 0.3-, 1.0-, and 2.0-mL vials) and Cat No. 33303 (20 mm for 5.0-mL 

vials)]. These vials are recommended for storage of Stock Standard Solutions and Primary 

Dilution Standards prepared in methanol. 

6.8 PURGE AND TRAP SYSTEM – Any purge-and-trap unit that is capable of being 

electronically interfaced to the GC to trigger the GC run and that is capable of meeting the 

method QC requirements outlined in Section 9 is permitted. The concentrator(s) may be 

equipped with an autosampler. Moisture control modules are permitted but not required. 

6.8.1 SPARGING VESSEL – Instruments must be equipped with a sparging vessel 

specifically designed for purging a 5-mL sample volume. A glass frit should be 

installed at the base of the sample chamber so the purge gas passes through the water 

column as finely divided bubbles with a diameter of less than 3 mm at the origin. 

NOTE: Larger sparging vessels are not allowed. While the larger sample volume 

could result in the transfer of more analyte to the trap, purging efficiency decreases 

unless the purge volume is increased proportionally. While the procedural calibration 

technique corrects for this, lower purging efficiency decreases method precision. In 

addition, larger purge volumes could result in the transfer of more water vapor to the 

trap, placing increased demand on the efficiency of moisture control devices. 

 

6.8.2 SORBENT TRAP – Purge-and-trap manufacturers typically recommend specific 

sorbent traps for use with their instruments. Any trap design is acceptable provided 

the data acquired meet all QC criteria described in Section 9. 

NOTE: During method development studies, a trap containing Tenax, silica gel and 

coconut charcoal in series exhibited complete breakthrough of 

chlorodifluoromethane. A trap containing Tenax, silica gel and carbon molecular 

sieve (CMS) exhibited partial breakthrough for chlorodifluoromethane. 

Chlorodifluoromethane cannot be analyzed using this method if these traps and traps 

of similar design, containing Tenax, silica gel and coconut charcoal, or Tenax, silica 

gel and CMS, are used. 

6.8.3 TRANSFER LINE – Silcosteel®, or equivalent, heated transfer line used to transfer 

the desorbed analytes from the purge-and-trap concentrator to the injection port of the 

GC. 

6.8.4 SAMPLE HEATER – A sparging vessel heater is optional. Resistance or infrared 

heaters may be used. 
 

524.3-11

6.8.5 REFRIGERATED AUTOSAMPLER – Vial autosamplers must be capable of 

maintaining samples at a temperature of 10 °C or lower. Verify the temperature of 

field samples placed in the autosampler using an external thermocouple or 

thermometer (inserted into a vial containing water) during the IDC and reconfirm at 

least quarterly. This temperature must not be altered after collecting the initial 

calibration because it may change analyte purging efficiencies. 

6.8.6 STANDARD ADDITION MODULE – Automated device incorporated into vial 

autosamplers capable of fortifying internal standards and surrogate analytes directly 

into the sparging vessel. A standard addition module is recommended when vial 

autosamplers are used to conduct this method. 

6.8.7 TANDEM PURGE-AND-TRAP OPERATION – A technique allowing use of two 

purge-and-trap concentrators configured in tandem. The IDC procedure (Sect. 9.2) 

must be conducted for each concentrator. In addition, this option requires separate 

QC samples for each sample path (Sect. 9.3), separate calibrations (Sect. 10), and the 

use of a marker compound (Sect. 10) to uniquely identify the sample path. 

6.9 GAS CHROMATOGRAPHY MASS SPECTROMETRY SYSTEM/DATA SYSTEM 

(GC/MS/DS) 

6.9.1 GC INJECTOR AND OVEN – The GC must be capable of temperature programming 

and must be equipped with a standard split/splitless injector and a flow controller that 

is compatible with purge-and-trap analysis. In this configuration, the purge-and-trap 

effluent is plumbed directly to the carrier gas inlet line of a split/splitless injection 

port. The injection port is operated in split mode to achieve the desired desorb flow 

rate and reduce water transmission. A deactivated glass liner (Restek Cat. No. 20972 

or equivalent) is recommended to minimize dead volume and active sites within the 

GC inlet. 

6.9.2 FUSED SILICA CAPILLARY GC COLUMN – Laboratories must use a column 

specifically designed for analysis of volatile organic compounds by purge and trap. 

The column must have an i.d. of 0.32 mm or less to be compatible with operation in 

the split mode (Sect. 6.9.1). The column must be capable of resolving the method 

analytes such that a unique quantitation ion is available for each analyte that is free 

from interference due to an identical fragment ion in any co-eluting (or overlapping) 

peak(s). 

 

6.9.3 GC/MS INTERFACE – The mass spectrometer must have sufficient vacuum 

pumping capacity to allow the direct feed of the analytical column to the ion source. 

6.9.4 MASS SPECTROMETER (MS) – The MS must be capable of electron ionization 

(EI) at a nominal energy of 70 electron volts (eV) and must be operated in the 

positive ion mode. An ion-trap mass spectrometer, tuned to produce mass spectra 

that approximate standard, library spectra obtained under EI conditions, may be used. 

The instrument must be capable of obtaining at least six scans during elution of each 

chromatographic peak. Seven to ten scans across chromatographic peaks are 

recommended. The spectrometer must produce a mass spectrum that meets all 
 

524.3-12

criteria in Table 1 when 4-bromofluorobenzene (BFB) is introduced into the GC/MS 

(Sect. 10.1.1). 

6.9.5 DATA SYSTEM – An interfaced data system is required to acquire, store, reduce, 

and output mass spectral data. The computer software must have the capability of 

processing stored GC/MS data by recognizing a GC peak within any given retention 

time window, comparing the mass spectra from the GC peak with spectral data in a 

user-created data base, and generating a list of tentatively identified compounds with 

their retention times and scan numbers. The software must allow integration of the 

ion abundance of any specific ion between specified time or scan number limits. The 

software must also allow construction of linear or second-order regression calibration 

curves, and calculation of concentrations using the internal standard technique. 

7. REAGENTS AND STANDARDS

7.1 REAGENTS AND SOLVENTS – Reagent grade or better chemicals must be used. Unless 

otherwise indicated, it is intended that all reagents will conform to the specifications of the 

Committee on Analytical Reagents of the American Chemical Society (ACS), where such 

specifications are available. Other grades may be used as long as the reagent is of sufficiently 

high purity to permit its use without negatively affecting data quality. 

7.1.1 HELIUM – Ultra High Purity (99.999%) or equivalent, for use as GC carrier gas and 

purge gas. 

7.1.2 REAGENT WATER – Purified water which does not contain any measurable 

quantities of any method analytes or interfering compounds at or above 1⁄2 the MRL 

for each compound of interest. 

7.1.3 METHANOL (CH3OH, CAS# 67-56-1) – Purge-and-trap grade, demonstrated to be 

free of analytes and interferences (Burdick & Jackson Brand® for Purge and Trap 

Analysis Cat. No. 232 or equivalent). 

7.1.4 ASCORBIC ACID (C6H8O6, CAS# 50-81-7) – Dechlorinating agent, demonstrated to 

be free of analytes and interferences (Alfa Aesar Cat. No. A15613 or equivalent). 

7.1.5 MALEIC ACID (C4H4O4, CAS# 110-16-7) – Used as a preservative and to lower pH 

for the purpose of preventing dehydrohalogenation of chlorinated analytes. High 

purity, demonstrated to be free of analytes and interferences (Sigma Cat. No. M0375 

or equivalent). 

7.1.6 SODIUM THIOSULFATE (Na2S2O3, CAS# 7772-98-7) – Optional dechlorinating 

agent when sampling only for THMs (Sigma Cat. No. 563188 or equivalent). 

7.2 STOCK STANDARD SOLUTIONS – Certified mixes of the 524.3 method analytes, the 

internal standards and the surrogate analytes are recommended. Users may prepare stock 

standards of the liquid and solid analytes, if not available as certified solutions, following the 

guidance provided in this section. After opening the sealed ampoules, store commercial 

mixes in micro-reaction vials with Mininert caps (Sect. 6.7) at a temperature of -10 °C or 

lower. After transfer, replace vendor-supplied, stock solutions within one month. 
 

524.3-13

NOTE: Methyl iodide may degrade faster than other liquid analytes. Monitor the area of this 

compound relative to the internal standard, 1, 4-difluorobenzene. Replace the stock standard 

if methyl iodide shows evidence of degradation. 

7.2.1 INTERNAL STANDARD STOCK SOLUTIONS (ISSS) (1000 to 2500 μg/mL) – 

This method uses three internal standards: 1,4-difluorobenzene (CAS# 540-36-3), 

chlorobenzene-d5 (CAS# 3114-55-4) and 1,4-dichlorobenzene-d4 (CAS# 3855-82-1). 

7.2.2 SURROGATE STOCK STANDARDS (SURSS) (1000 to 2500 μg/mL) – This 

method uses three surrogate analytes: methyl-t-butyl-ether-d3 (CAS# 29366-08), BFB 

(CAS# 460-00-4) and 1,2-dichlorobenzene-d4 (CAS# 2199-69-1). 

NOTE: During method development, methyl-t-butyl-ether-d3 was obtained as the neat 

compound (Aldrich Cat. No. 43413-2 or equivalent).

7.2.3 ANALYTE STOCK STANDARD SOLUTIONS – Obtain the analytes listed in the 

table in Section 1.1 as certified mixes in methanol, or as neat standards if necessary. 

During method development, the reformulated gasoline additives were obtained as 

custom mixes in methanol and as neat materials. Chlorodifluoromethane, and 1,3-

butadiene (new method analytes in revision 524.3) were obtained as custom mixes in 

methanol. 

7.2.4 PREPARATION INSTRUCTIONS FOR LIQUID ANALYTES – Prepare the stock 

standards individually at 10 mg/mL. Using an analytical balance, obtain a tare weight 

for a VOA vial containing 20-mL of purge-and-trap-grade methanol. To achieve the 

10 mg/L nominal concentration, calculate the volume of the liquid analyte 

corresponding to 200 mg. Carefully measure this volume with a 250-μL syringe and 

inject the entire quantity under the surface of the methanol. Subtract the tare weight 

from the final weight to calculate the exact solution concentration. When a 

compound’s purity is assayed to be 96 percent or greater, the weight can be used 

without correction to calculate the concentration of the stock standard. 

7.2.5 PREPARATION INSTRUCTIONS FOR SOLID ANALYTES - Prepare the stock 

standards individually at 10 mg/mL by weighing 200 mg of each solid analyte into a 

40-mL VOA vial and diluting to 20 mL. Using an analytical balance, weigh 

approximately 200 mg of the solid material using a small glass weigh boat or similar 

device. Transfer the solid to a 40-mL VOA vial and add 20-mL of purge-and-trapgrade methanol. For semi-solid and other difficult to transfer materials, insert the 

entire weigh boat into a VOA vial containing 20-mL of methanol. If the measured 

mass of analyte is not exactly 200 mg, adjust the volume of methanol to achieve a 

nominal concentration of 10 mg/mL. When a compound’s purity is assayed to be 96 

percent or greater, the weight can be used without correction to calculate the 

concentration of the stock standard. 
 

524.3-14

7.2.6 STORAGE OF INDIVIDUAL STOCK STANDARDS - Store stock standards in the 

VOA vials in which they were prepared. Stock standard solutions of liquid and solid 

analytes prepared in-house are estimated to be stable for at least six months if stored at 

-10 °C or colder. However, such solutions may be stable for longer periods depending 

on the analyte. Laboratories must use accepted QC practices to determine when stock 

standards need to be replaced. 

7.3 PRIMARY DILUTION STANDARDS – Prepare Primary Dilution Standards by combining 

and diluting appropriate volumes of the stock standards with purge-and-trap-grade methanol. 

7.3.1 INTERNAL STANDARD AND SURROGATE PRIMARY DILUTION 

STANDARD (IS/surrogate PDS) – Prepare a combined internal standard and 

surrogate PDS from the ISSS and SURSS. Field samples and calibration standards 

must contain the same concentration of internal standards and surrogates, and the 

quantity of methanol added should be minimized. Between one and 5 μL per 5-mL 

sample is recommended. An IS/surrogate PDS concentration that results in the 

aqueous concentration falling in the mid-range of the initial calibration, e.g., 5 μg/L in 

full scan mode and 0.5 μg/L in SIM mode is recommended. Store the IS/surrogate 

PDS in a glass vial with Teflon-lined septa at a temperature of -10 °C or colder. 

However, the IS/surrogate PDS may be held at room temperature for extended periods 

(several months) if stored in the sealed reservoir of a standard addition module. 

7.3.2 ANALYTE PRIMARY DILUTION STANDARD (analyte PDS) – The analyte PDS is 

used to prepare the calibration standards and to fortify LFBs, LFSMs and LFSMDs 

with the method analytes. The analyte PDS is prepared by combining appropriate 

volumes of the analyte stock standard solutions to achieve concentrations appropriate 

for preparing aqueous calibration standards and fortifying samples. Choose 

concentrations such that at least 2 μL of the PDS is transferred to achieve the desired 

aqueous concentration in the standard or QC samples. During method development, 

PDS solutions ranged in concentration from 10 μg/mL to 400 μg/mL. Lower 

concentrations of the analyte PDS may be necessary when conducting analyses in SIM 

mode. Store analyte PDS solutions in micro-reaction vials with Mininert caps at a 

temperature of -10 °C or colder. PDS solutions which contain gasses must be replaced 

after one week; those which do not contain gases may be stored for up to one month. 

7.4 CALIBRATION STANDARDS – Prepare procedural calibration standards by diluting the 

analyte PDS into reagent water containing the method preservatives (Sect. 8.1) at the same 

concentrations used to collect the samples. A constant concentration of each internal standard 

and surrogate analyte is added to each calibration standard, either manually or by use of an 

automated standard addition module (Sect. 6.8.6). The lowest concentration calibration 

standard must be at or below the MRL. These calibration standards may also be used as 

CCCs. The dilution schemes for calibration standards that were used to collect method 

performance data in Section 17 are provided in the tables below. 
 

524.3-15

Typical concentrations for aqueous calibration standards in scan mode used during method 

development: 

CALa Level Analyte PDS Conc. (μg/mL) 

Analyte PDS 

Volume (μL) Final CAL Std. Volume (L) 

Final CAL Std. Conc. 

(μg/L) 

1 10 5.0 0.100 0.50 

2 10 10 0.100 1.0 

3 100 2.0 0.100 2.0 

4 100 5.0 0.100 5.0 

5 400 2.5 0.100 10 

6 400 5.0 0.100 20 

7 400 10 0.100 40 a CAL = calibration standard.

Typical concentrations for aqueous calibration standards in SIM mode used during method 

development: 

 

CAL Level Analyte PDS Conc. (μg/mL) 

Analyte PDS 

Volume (μL) Final CAL Std. Volume (L) 

Final CAL Std. Conc. 

(ng/L) 

1 0.1 2.0 0.100 2.0 

2 0.1 5.0 0.100 5.0 

3 0.1 10 0.100 10 

4 1.0 2.5 0.100 25 

5 1.0 5.0 0.100 50 

6 1.0 10 0.100 100 

7 10 2.0 0.100 200 

8 10 5.0 0.100 500 

9 10 10 0.100 1,000 

10 100 2.0 0.100 2,000 

11 100 5.0 0.100 5,000 

7.5 GC/MS TUNE CHECK SOLUTION, BFB (CAS# 460-00-4) – Use the IS/surrogate analyte 

PDS (Sect. 7.3.1). 

8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1 SAMPLE COLLECTION 

8.1.1 Prior to shipment to the field, maleic and ascorbic acid must be added to each sample 

bottle. Cap the vials tightly to avoid spillage of the preservation reagents. If using a 

40-mL vial, add 25 mg of ascorbic acid and 200 mg of maleic acid. If other 

collection volumes are used, adjust the amount of the preservation reagents so that the 

final concentrations of ascorbic and maleic acid in the sample containers are 0.625 

g/L and 5 g/L, respectively. Using narrow-range pH paper, periodically verify that 

sample pH is ~2 for each sample source. 

8.1.2 If a sample foams vigorously when added to a VOA vial containing maleic and 

ascorbic acids, discard the sample. Collect another sample for that location, but do 

not add the method preservatives. Document these samples as “not acidified.” 

Unpreserved samples must be analyzed within 24 hours of collection. 
 

524.3-16

8.1.3 If sampling only for the THMs, you may preserve samples with sodium thiosulfate. 

Add 3 mg to each 40-mL VOA vial prior to sample collection. Do not add ascorbic 

or maleic acid when employing this preservation option. 

NOTE: If the residual chlorine is likely to be present at greater than 5 mg/L, a 

determination of the chlorine concentration may be necessary. Add an additional 25 

mg of ascorbic acid or 3 mg of sodium thiosulfate per each 5 mg/L of residual 

chlorine for each 40-mL of sample. 

8.1.4 Grab samples must be collected in accordance with standard sampling practices.5 

When sampling from a cold water tap, remove the aerator, open the tap and allow the 

system to flush until the water temperature has stabilized (approximately 3 to 5 

minutes). Fill sample bottles to overflowing, but take care not to flush out the rapidly 

dissolving solid preservatives. No air bubbles should pass through the sample as the 

bottle is filled, or be trapped in the sample when the bottle is sealed. 

8.1.5 When sampling from an open body of water, fill a beaker with water collected from a 

representative area. Use this bulk sample to generate individual samples and Field 

Duplicates as needed. 

8.2 FIELD REAGENT BLANKS 

8.2.1 Duplicate FRBs must accompany each sample set, which is composed of the samples 

collected from the same general sampling site at approximately the same time. At the 

laboratory, add the sample preservatives to the FRB sample bottles, fill with reagent 

water, and ship the FRBs with the sampling kits. Do not open FRBs in the field; 

FRBs must remain sealed until analysis. 

8.2.2 Use the same procedure to prepare sample containers for both FRBs and field 

samples. Whenever possible, the same lots of ascorbic acid and maleic acid must be 

used for the Field Reagent Blanks as for the field samples. 

8.3 FIELD DUPLICATES – At a minimum, collect all samples in duplicate. If the samples will 

be analyzed using a vial autosampler, collect additional Field Duplicates to fulfill QC 

requirements for LFSMs, and LFSMDs (at least three identical samples). Collect additional 

duplicate samples if separate analysis in SIM mode is anticipated. 

8.4 SAMPLE SHIPMENT AND STORAGE – Samples must be chilled during shipment and 

must not exceed 10 °C during the first 48 hours after collection. Samples must be confirmed 

to be at or below 10 °C when they are received at the laboratory. In the laboratory, samples 

must be stored at or below 6 °C, protected from light, and isolated from ambient sources of 

VOCs. When resident in the autosampler, samples must be held at 10 °C or lower. Samples 

must not be frozen. 

8.5 SAMPLE HOLDING TIMES – Analyze samples as soon as possible. Samples that are 

collected and stored as described in Section 8.1 and 8.4 must be analyzed within 14 days of 

collection. 
 

524.3-17

9. QUALITY CONTROL

QC requirements include the Initial Demonstration of Capability and ongoing QC requirements. 

This section describes each QC parameter, its required frequency, and the performance criteria that 

must be met in order to satisfy EPA quality objectives. The QC criteria discussed in the following 

sections are summarized in Section 17, Tables 15 and 16. These QC requirements are considered 

the minimum acceptable QC criteria. Laboratories are encouraged to institute additional QC 

practices to meet their specific needs. Compliance with the requirements of the IDC must be 

demonstrated for each analyte that the laboratory intends to report using full scan MS, and for each 

analyte that the laboratory intends to report in the SIM or SIS detection mode. 

9.1 METHOD MODIFICATIONS – The analyst is permitted to select purge-and-trap and GC 

conditions appropriate for the available instrumentation. However, five key parameters are 

restricted to prescribed ranges. These ranges are summarized in the table below. If the 

chosen parameters fall within the “recommended” ranges, the laboratory may proceed with 

the IDC. If values outside the “recommended” ranges are selected for any one of these five 

parameters, the laboratory must demonstrate equivalent performance in accordance with the 

guidelines provided in Section 9.4, and then the analyst must repeat the procedures of the 

IDC. However, values for the five key parameters must never exceed the “allowable” ranges 

listed in the table below. In addition, sample size cannot be varied from the 5-mL volume 

prescribed in this method. All other parameters including the remaining concentrator 

conditions, GC conditions and MS conditions may be varied without restriction. 

Recommended Allowable 

Parameter Minimum Maximum Minimum Maximum 

Sample temperature Ambient 40 oC Ambient 60 °C 

Purge flow rate 40 mL/min 80 mL/min 20 mL/min 200 mL/min 

Purge volume 360 mL 520 mL 240 mL 680 mL 

Desorb time 1 min 2 min 0.5 min 4 min 

Purge volume + dry purge volume 360 mL 720 mL 240 mL 880 mL 

NOTE: Three commercially available purge-and-trap concentrators, varying in design and 

water management systems, were evaluated to determine these minimum and maximum 

parameter settings. The “recommended” values provided equivalent response factors and 

internal standard areas within the ranges specified in the table. The “allowable” limits 

resulted in a wider variation in response factors, particularly for those analytes with low purge 

efficiencies; however, operation within this range may be appropriate for limited analyte lists 

and other concentrator designs. Sample temperature is limited to 60 oC to avoid acidcatalyzed decomposition of method analytes. See Table 2 in Section 17 for typical values for 

purge-and-trap parameters. 

9.2 INITIAL DEMONSTRATION OF CAPABILITY (IDC) – The IDC must be successfully 

performed prior to analyzing any field samples. Prior to conducting the IDC, the analyst must 

meet the calibration requirements outlined in Section 10. The IDC must be completed for 

each concentrator and trap design. For example, if dual concentrators are interfaced to a 

single GC/MS, perform the IDC for each system. If a new trap is installed with sorbent 

materials different from the original trap, repeat the IDC. Requirements for the IDC are 

described in the following sections and are summarized in Table 15. 
 

524.3-18

9.2.1 DEMONSTRATION OF LOW SYSTEM BACKGROUND – Analyze an LRB. 

Confirm that the blank is free of contamination as defined in Section 9.3.1. 

NOTE: The method must be checked for carryover by analyzing an LRB 

immediately following the highest calibration standard. If this LRB does not meet the 

criteria outlined in Section 9.3.1, then carryover is present and the cause must be 

identified and eliminated. 

9.2.2 DEMONSTRATION OF PRECISION – Prepare and analyze seven replicate LFBs. 

Fortify these samples near the midrange of the initial calibration curve. The method 

preservation reagents must be added to the LFBs as described in Section 8.1. The 

percent relative standard deviation (RSD) of the concentrations of the replicate 

analyses must be ≤20% for all method analytes. 

100

AverageConcentration

Standard Deviation of Measured Concentrations % RSD = ×

9.2.3 DEMONSTRATION OF ACCURACY – Calculate the average percent recovery 

using the same set of replicate data generated for Section 9.2.2. The average recovery 

of the replicate analyses must be within +20% of the true value. 

100

Fortified Concentration

AverageMeasuredConcentration % Recovery = ×

9.2.4 MINIMUM REPORTING LEVEL (MRL) CONFIRMATION – Establish a target 

concentration for the MRL based on the intended use of the data. The lowest 

calibration standard used to establish the initial calibration (as well as the low-level 

Continuing Calibration Check) must be at or below the concentration of the MRL. 

Establishing the MRL concentration too low may cause repeated failure of ongoing 

QC requirements. Confirm the MRL following the procedure outlined below. 

NOTE: Method analytes that are consistently present in the background (e.g., 

methylene chloride, TBA) should be reported as detected in field samples only after 

careful evaluation of the background levels. In such cases, an MRL must be 

established at a value no less than three times the standard deviation of the mean LRB 

concentration or three times the mean LRB concentration, whichever is greater. The 

MRL must be calculated over an extended time period to reflect variability in the 

blank measurements. This guidance is intended to minimize the occurrence of 

reporting false positive results. 

9.2.4.1 Fortify and analyze seven replicate LFBs at or below the proposed MRL 

concentration. The LFBs must contain the method preservatives as 

specified in Section 8.1. Calculate the mean (Mean) and standard deviation 

(S) for these replicates. Determine the Half Range for the Prediction 

Interval of Results (HRPIR) using the equation below 

HRPIR = 3.963S
 

524.3-19

 where S is the standard deviation, and 3.963 is a constant value for seven 

replicates.1

9.2.4.2 Confirm that the Upper and Lower limits for the Prediction Interval of 

Results (PIR = Mean + HRPIR) meet the upper and lower recovery limits as 

shown below. 

 The Upper PIR Limit must be ≤150% recovery. 

Mean HR

FortifiedConcentration

PIR +

× ≤ 100 150%

 The Lower PIR Limit must be ≥50% recovery. 

Mean HR

FortifiedConcentration

PIR − × ≥ 100 50%

9.2.4.3 The MRL is validated if both the Upper and Lower PIR Limits meet the 

criteria described above. If these criteria are not met, the MRL has been set 

too low and must be confirmed again at a higher concentration. 

NOTE: These equations are only valid for seven replicate samples. 

9.2.5 QUALITY CONTROL SAMPLE (QCS) – Analyze a mid-level Quality Control 

Sample (Sect. 9.3.10) to confirm the accuracy of the primary calibration standards. 

9.2.6 DETECTION LIMIT DETERMINATION (optional) – While DL determination is 

not a specific requirement of this method, it may be required by various regulatory 

bodies associated with compliance monitoring. It is the responsibility of the 

laboratory to ascertain whether DL determination is required based upon the 

intended use of the data.

Analyses for this procedure must be done over at least three days. Prepare at least 

seven replicate LFBs. Fortify the LFBs at a concentration estimated to be near the 

DL. This fortification level may be estimated by selecting a concentration at two to 

five times the noise level. The method preservatives must be added to the samples as 

described in Section 8.1. Process the seven replicates through all steps of Section 11. 

NOTE: If a data set used for the MRL confirmation step of the IDC meets these 

requirements, a DL may be calculated from the MRL confirmation data, and no 

additional analyses are necessary. 

 Calculate the DL using the following equation: 

DL = S x t(n-1,1-α = 0.99) 
 

524.3-20

 where 

 t(n-1,1-α = 0.99) = Student's t value for the 99% confidence level with n-1 degrees of 

freedom (for seven replicate determinations, the Student’s t value 

is 3.143 at a 99% confidence level), 

 n = number of replicates, and 

 S = standard deviation of replicate analyses. 

NOTE: Do not subtract blank values when performing DL calculations. 

9.3 ONGOING QC REQUIREMENTS – This section describes the ongoing QC procedures that 

must be followed when processing and analyzing field samples. Table 16 summarizes these 

requirements. 

9.3.1 LABORATORY REAGENT BLANK (LRB) – Analyze an LRB with each Analysis 

Batch. The LRB must contain the method preservatives, the internal standards, and 

surrogate analytes at the same concentration used to fortify all field samples and 

calibration standards. Background from method analytes or contaminants that interfere with the measurement of method analytes must be less than 1⁄2 the MRL. If the 

method analytes are detected in the LRB at concentrations equal to or greater than 

this level, then all data for the problem analyte(s) must be considered invalid for all 

samples that yielded a positive result. Subtracting LRB values from sample results 

is not permitted. 

NOTE: Although quantitative data below the MRL may not be accurate enough for 

data reporting, such data are useful in determining the magnitude of background 

interference. Therefore, blank contamination levels may be estimated by 

extrapolation when the concentration is below the MRL. 

NOTE: After analysis of a sample in which method analytes exceed the calibration 

range, one or more LRBs must be analyzed (to detect potential carryover) until the 

system meets the LRB acceptance criteria. If this occurs during an automated 

sequence, examine the results of samples analyzed following the sample that 

exceeded the calibration range. If the analytes that exceeded the calibration range in 

the previous sample are detected at or above the MRL, these samples are invalid. If 

the affected analytes do not exceed the MRL, these subsequent samples are valid. 

THMs are excluded from this requirement. 

NOTE: The LRB test in the IDC may be particularly difficult to pass for compounds 

analyzed using the SIM detection mode. For anaytes monitored in SIM mode, the 

laboratory should restrict the high calibration point to 1.0 or 2.0 μg/L, and consider 

other techniques such as using a dedicated sparge vessel and more aggressive recycle 

parameters. If possible, select MRLs that allow monitoring goals to be achieved, but 

that are well above typical blank values. 

9.3.2 CONTINUING CALIBRATION CHECK (CCC) – Analyze CCC standards at the 

beginning of each Analysis Batch, after every ten field samples, and at the end of the 

Analysis Batch. See Section 10.2 for concentration requirements and acceptance 

criteria. 
 

524.3-21

 

9.3.3 LABORATORY FORTIFIED BLANK (LFB) – Because this method utilizes 

procedural calibration standards, which are fortified reagent waters, there is no 

difference between the LFB and the CCC standards. Consequently, the analysis of a 

separate LFB is not required as part of the ongoing QC; however, the term “LFB” is 

used for clarity in the IDC. 

9.3.4 MS TUNE CHECK – The procedure for conducting the MS Tune Check for BFB is 

found in Section 10.1.1. Acceptance criteria for the MS Tune Check are summarized 

in Section 17, Table 1. The MS Tune Check must be performed prior to establishing 

and/or re-establishing an initial calibration (Sect. 10.1) and each time a major change 

is made to the mass spectrometer. Daily BFB analysis is not required. 

9.3.5 INTERNAL STANDARDS (IS) – The analyst must monitor the peak areas of the 

internal standards in all injections of the Analysis Batch. The IS responses (peak 

area) in any chromatographic run must not deviate from the response in the most 

recent CCC by more than +30%, and must not deviate by more than +50% from the 

average area measured during initial analyte calibration. If an IS area for a sample 

does not meet these criteria, check the corresponding IS area of the most recent CCC 

and proceed as follows. 

9.3.5.1 If the IS criteria are met in the CCC but not the sample, reanalyze the 

sample (Field Duplicate) in a subsequent Analysis Batch. If the IS area fails 

to meet the acceptance criteria in the Field Duplicate, but passes in the most 

recent CCC, report the sample results as “suspect/matrix.” 

9.3.5.2 If both the original sample and the CCC fail the IS criteria, take corrective 

action beginning with an extended bake cycle for the GC column and the 

concentrator trap. Area counts may decrease as the rate of water entering 

the mass spectrometer exceeds the capacity of the pumping system to 

remove it. Additional measures such as clipping the inlet side of the GC 

column and cleaning the MS source may be indicated. Verify the integrity 

of the IS solution and the fortification technique. Perform the appropriate 

instrument maintenance and then reanalyze the sample (Field Duplicate) in a 

subsequent Analysis Batch. If the IS area fails to meet the acceptance 

criteria in the Field Duplicate, but passes in the most recent CCC, report the 

sample results as “suspect/matrix.” 

9.3.6 SURROGATE RECOVERY – The surrogate analytes are fortified into all calibration 

standards, field samples, and QC samples prior to purge-and-trap analysis. Calculate 

the percent recovery (%R) for each surrogate using the following equation: 

100

B

A %R ⎟×

⎠

⎞ ⎜

⎝

⎛ =

where 

A = calculated surrogate concentration for the QC or field sample, and 

B = fortified concentration of the surrogate. 
 

524.3-22

9.3.6.1 Surrogate recovery must be in the range of 70% to 130%. When surrogate 

recovery from a field sample, blank, or QC sample is less than 70% or 

greater than 130%, check: 1) calculations to locate possible errors, 2) the 

integrity of the surrogate analyte solution and the fortification technique, 

3) contamination, and 4) instrument calibration. Also, see corrective action 

options in Section 9.3.5.2. Correct the problem and reanalyze the sample in 

a subsequent Analysis Batch using the appropriate Field Duplicate. 

9.3.6.2 If the repeat analysis meets the surrogate recovery criterion, only report data 

for the Field Duplicate. 

9.3.6.3 If the Field Duplicate fails the surrogate recovery criterion after corrective 

action has been taken, report all data for that sample as “suspect/surrogate 

recovery.” 

9.3.7 LABORATORY FORTIFIED SAMPLE MATRIX (LFSM) – Within each Analysis 

Batch, analyze a minimum of one LFSM. The native concentrations of the analytes 

in the sample matrix must be determined in a separate aliquot and subtracted from the 

measured values in the LFSM. If a variety of different sample matrices are analyzed 

regularly, for example, drinking water from ground water and surface water sources, 

performance data must be collected for each source. 

9.3.7.1 Prepare the LFSM by fortifying a Field Duplicate with an appropriate 

amount of an analyte PDS (Sect. 7.3.2). Select a spiking concentration that 

is greater than or equal to the native background concentration, if known. 

Selecting a duplicate aliquot of a sample that has already been analyzed aids 

in the selection of an appropriate spiking level. If this is not possible, use 

historical data and rotate through low, medium, and high calibration 

concentrations when selecting a fortifying concentration. 

 NOTE: If the presence of disinfection byproducts (DBPs) (e.g., THMs) 

precludes selection of an appropriate fortification level for the majority of 

the method analytes, the DBPs may be ignored. For example, if the analyst 

wishes to estimate accuracy and precision at 1.0 μg/L, and chloroform is 

present in the native matrix at 10 μg/L, chloroform is fortified at only 10% 

of its native concentration. In such cases, recovery results for the DBPs may 

fail the acceptance criteria for LFSM. Appropriately qualify the QC result 

when this occurs. If the laboratory is analyzing specifically for DBPs, or 

does not wish to exclude them, select a fortification level based on the DPB 

concentrations in the native sample such that the final DBP results fall 

within the calibration range. 

9.3.7.2 Calculate the percent recovery (%R) using the equation: 

( ) 100

C

A - B %R = ×
 

524.3-23

 where 

 A = measured concentration in the fortified sample, 

 B = measured concentration in the unfortified sample, and 

 C = fortification concentration. 

9.3.7.3 Recoveries for samples fortified at concentrations near or at the MRL 

(within a factor of two times the MRL concentration) must be within +50% 

of the true value. Recoveries for samples fortified at all other concentrations 

must be within +30% of the true value. If the accuracy for any analyte falls 

outside the designated range, and the laboratory performance for that analyte 

is shown to be in control in the CCCs, the recovery is judged matrix biased. 

The result for that analyte in the unfortified sample is labeled 

“suspect/matrix.” 

NOTE: In order to obtain meaningful percent recovery results, correct the 

measured values in the LFSM and LFSMD for the native levels in the 

unfortified samples, even if the native values are less than the MRL. This 

situation and the LRB are the only permitted uses of analyte results below 

the MRL.

9.3.8 FIELD DUPLICATE OR LABORATORY FORTIFIED SAMPLE MATRIX 

DUPLICATE (FD or LFSMD) – Within each Analysis Batch, analyze a minimum of 

one Field Duplicate or one Laboratory Fortified Sample Matrix Duplicate. If method 

analytes are not routinely observed in field samples, analyze an LFSMD rather than 

an FD. 

9.3.8.1 Calculate the relative percent difference (RPD) for duplicate measurements 

(FD1 and FD2) using the equation: 

( ) 100

FD FD /2

FD FD

RPD

1 2

1 2

×

+

− =

9.3.8.2 RPDs for Field Duplicates must be ≤30%. Greater variability may be 

observed when Field Duplicates have analyte concentrations that are near or 

at the MRL (within a factor of two times the MRL concentration). At these 

concentrations, Field Duplicates must have RPDs that are ≤50%. If the 

RPD of an analyte falls outside the designated range, and the laboratory 

performance for the analyte is in control in the CCC, the precision is judged 

matrix influenced. The result from the unfortified sample is labeled 

“suspect/matrix.” 

9.3.8.3 If an LFSMD is analyzed instead of a Field Duplicate, calculate the RPD for 

the LFSM and LFSMD using the equation: 

( ) 100

LFSM LFSMD /2

LFSM LFSMD

RPD ×

+

− =
 

524.3-24

9.3.8.4 RPDs for duplicate LFSMs must be ≤30%. Greater variability may be 

observed when fortified LFSMs have analyte concentrations that are near or 

at the MRL (within a factor of two times the MRL concentration). LFSMs 

at these concentrations must have RPDs that are ≤50%. If the RPD of an 

analyte falls outside the designated range, and the laboratory performance 

for that analyte is in control in the CCC, the precision is judged matrix 

influenced. The result from the unfortified sample is labeled 

“suspect/matrix.” 

9.3.9 FIELD REAGENT BLANK (FRB) – FRBs must be analyzed if compounds other 

than commonly occurring DBPs, such as THMs, are detected in field samples. 

Qualify the result for any analyte that is detected in both a field sample and in the 

associated FRB as “probable contribution from shipping and storage.” Subtracting 

FRB values from sample results is not permitted. 

9.3.10 QUALITY CONTROL SAMPLE (QCS) – A QCS must be evaluated as part of the 

IDC, and repeated at least quarterly. Fortify the QCS near the midpoint of the 

calibration range. The acceptance criteria for the QCS are the same as the mid-level 

and high-level CCCs (Sect. 10.2.1). If the accuracy for any analyte fails the recovery 

criterion, check the standard preparation process, stock standard sources, and the 

purity of neat materials used to prepare the stock standards to locate and correct the 

problem. 

9.4 METHOD MODIFICATION QC REQUIREMENTS – The analyst is permitted to modify the 

five key purge-and-trap parameters (sample temperature, purge flow rate, purge volume, 

desorb time, and dry purge volume) selecting values outside of the “recommended” ranges 

(Sect. 9.1). The analyst is not permitted to modify sample collection and preservation, change 

the QC requirements of the method, or increase the sample volume above 5 mL. Do not add 

or delete QC compounds from the list prescribed in the method: ISs (Sect. 7.2.1) and 

surrogates (Sect. 7.2.2). Each time method modifications are proposed for one of the five key 

parameters; that is, outside of the “recommended” minimum and maximum, the laboratory 

must confirm that the new parameters provide acceptable method performance as defined in 

the following subsections. 

9.4.1 The new parameters must fall within the “allowable” minimum and maximum limits 

specified in Section 9.1. Values outside these limits are not permitted under any 

circumstances. 

9.4.2 Perform an initial calibration procedure (Sect. 10.1) for the method analytes that the 

laboratory intends to report using conditions that fall within the “recommended” 

ranges as presented in Section 9.1. Determine relative response factors (RRF) for 

each analyte averaged over the entire calibration range. 

( ) ( )

IS( ) area Analyte (μg/L)

Analyte area IS μg/L RRF

×

× =

9.4.3 Optimize the purge-and trap system using the proposed method modifications. 

Analyze three mid-level calibration standards and calculate mean RRFs for each 
 

524.3-25

method analyte. If all of the response factors observed using the modified conditions 

are ≥70% of the initial calibration response factors obtained using the 

“recommended” method conditions (Sect. 9.4.2), then the modified method 

parameters are permitted. Repeat the procedures of the IDC (Sect. 9.2) employing the 

modified parameters. 

9.4.4 The analyst is also required to evaluate and document method performance for the 

proposed method modifications in real matrices that span the range of waters that the 

laboratory analyzes. This additional step is required because modifications that 

perform acceptably in the IDC, which is conducted in reagent water, could fail 

ongoing method QC requirements in real matrices. If, for example, the laboratory 

analyzes drinking water from both surface and ground water municipalities, this 

requirement can be accomplished by assessing precision and accuracy (Sects. 9.2.2 

and 9.2.3) in a surface water with moderate to high total organic carbon (e.g., 2 mg/L 

or greater) and a hard ground water [e.g., 250 mg/L as calcium carbonate (CaCO3) 

equivalent, or greater]. 

9.4.5 The results of Sections 9.4.3 and 9.4.4 must be appropriately documented by the 

analyst and should be independently assessed by the laboratory’s QA officer prior to 

analyzing field samples. 

9.4.6 When implementing method modifications, it is the responsibility of the laboratory to 

closely review the results of ongoing QC, and in particular, the results associated with 

the LFSM (Sect. 9.3.7), LFSMD (Sect. 9.3.8), CCCs (Sect. 9.3.2), and the IS area 

counts (Sect. 9.3.5). If repeated failures are noted, the modification must be 

abandoned. 

10. CALIBRATION AND STANDARDIZATION

Demonstration and documentation of acceptable analyte calibration is required before performing 

the IDC (Sect. 9.2) and prior to analyzing field samples. Verification of the MS calibration and the 

initial calibration must be repeated each time a major instrument modification or maintenance is 

performed. 

NOTE: For tandem concentrators or older systems that utilize multiple sparging vessels and/or 

traps, a separate calibration and all required QC samples must be analyzed on each sample path. In 

addition, a qualitative marker compound must be added to all samples to uniquely identify the 

sample path, and ensure that samples are matched to the proper calibration and QC results. For 

example, fluorobenzene could be added to all samples analyzed on the second sample path of a 

tandem concentrator system. 

10.1 PURGE AND TRAP GC/MS OPTIMIZATION AND INITIAL CALIBRATION – An initial 

calibration requires optimizing purge-and-trap and GC/MS conditions, confirming that the 

instrument meets the BFB tune check criteria, and the preparation and analysis of at least 

seven calibration standards to determine the calibration curve. Calibration must be performed 

using peak areas and the internal standard technique. Calibration using peak heights and 

external standard calibration are not permitted. 
 

524.3-26

10.1.1 MS TUNE/MS TUNE CHECK– Calibrate the mass and abundance scales of the MS 

utilizing calibration compounds and procedures recommended by the manufacturer 

with any modifications necessary to meet tuning requirements. Introduce BFB (Sect. 

7.5) into the GC/MS system. Acquire a mass spectrum using the same scan range 

employed for full scan sample analyses. Use a single spectrum at the apex of the 

BFB peak, an average spectrum of the three highest points of the peak, or an average 

spectrum across the entire peak to evaluate the performance of the system. 

Appropriate background subtraction is allowed; however, the background scan(s) 

must be chosen from the baseline prior to or after elution of the BFB peak. If the 

BFB mass spectrum does not meet all criteria in Table 1, the MS must be retuned to 

meet all criteria before proceeding with the initial calibration. 

10.1.2 PURGE-AND-TRAP CONDITIONS – Establish purge-and-trap parameters 

following the manufacturer’s recommendations. Make sure that the sample 

temperature, purge flow rate, purge volume, desorb time, and dry purge volume are 

within the “allowable” ranges specified in section 9.1. Optimize purge-and-trap 

parameters to maximize purging efficiency and minimize the transmission of water to 

the GC/MS system. 

10.1.3 GC CONDITIONS – Establish GC operating conditions appropriate for the GC 

column dimensions by optimizing the split ratio and temperature program. Generally, 

the required split ratio is inversely proportional to column diameter. The user must 

balance the need to transfer enough of the method analytes to achieve the desired 

MRLs and the need to reduce water transmission from the purge-and-trap 

concentrator. The split ratio will also affect the chromatographic peak profile of the 

most volatile method analytes, commonly referred to as “gases.” Sufficient 

resolution and symmetrical peak profiles with minimal tailing for these analytes must 

be achieved to enable accurate and precise integration. A mass chromatogram of the 

gases obtained during method development is provided in Figure 1. The GC program 

must be optimized to provide adequate resolution of the method analytes as defined in 

the following subsections. 

10.1.3.1 If possible, optimize chromatographic conditions such that a unique 

quantitation ion is available for each analyte that is free from interference 

due to an identical fragment ion in any co-eluting (or overlapping) peak(s). 

10.1.3.2 If a unique quantitation ion of sufficient intensity to set the desired MRL is 

not available, overlap with an identical ion from an overlapping analyte is 

permitted, providing that at least a 50% valley between the mass peaks is 

achieved. 

10.1.4 FULL SCAN MS CONDITIONS – Select a scan range that allows the acquisition of 

a mass spectrum for each of the method analytes, which includes all of the major 

fragments mass-to-charge ratio (m/z) 35 and above. However, during elution of the 

water/carbon dioxide peak, the analyst is permitted to begin the scan at m/z 45 to 

eliminate the appearance of these matrix components in the baseline. 

10.1.5 SIM MS CONDITIONS – In SIM mode, choose one primary quantitation ion and at 

least one secondary ion. If possible, select a second confirmation ion. Additional 
 

524.3-27

ions may be monitored that demonstrate a unique characteristic in the mass spectrum 

such as a halogen cluster. Verify that the primary ion is free from interference (Sect. 

10.1.3.1 and Sect. 10.1.3.2) due to an identical fragment ion in any overlapping 

peak(s). If the chromatogram is divided into SIM windows (also termed segments or 

periods), the laboratory must ensure that each method analyte elutes entirely within 

the proper window during each Analysis Batch. Make this observation by viewing 

the mass chromatogram of the quantitation ion for each SIM analyte in the CCC 

analyzed at the beginning and end of each Analysis Batch. This requirement does not 

preclude continuous operation by sequencing multiple Analysis Batches; however, 

the entire Analysis Batch is invalid if one or more analyte peaks drift outside of 

designated SIM windows in either of these CCCs. 

10.1.6 ALTERNATING FULL AND SIM SCAN MODES – Alternating full and SIM scan 

functions during a single sample acquisition is permitted if the minimum number of 

scans across each GC peak acquired in this mode is maintained, i.e., six scans as 

specified in Section 6.9.4 in each full and SIM scan modes. 

10.1.7 CALIBRATION STANDARDS – Prepare a set of at least seven calibration standards 

as described in Section 7.4. The lowest concentration of the calibration standards 

must be at or below the MRL. The MRL must be confirmed using the procedure 

outlined in Section 9.2.4 after establishing the initial calibration. Additionally, field 

samples must be quantified using a calibration curve that spans the same 

concentration range used to collect the IDC data (Sect. 9.2), e.g., analysts are not 

permitted to use a restricted calibration range to meet the IDC criteria and then use a 

larger dynamic range during analysis of field samples. 

10.1.8 CALIBRATION – Calibrate the GC/MS system using peak areas and the internal 

standard technique. Fit the calibration points with either a linear or a quadratic 

regression (response vs. concentration). Weighting may be used. The GC/MS 

instrument used during method development was calibrated using inverse 

concentration-weighted quadratic curves. Suggested internal standard assignments 

and quantitation ions for each method analyte evaluated in full scan mode are 

presented in Table 4. Suggested internal standard assignments and quantitation ions 

for each method analyte evaluated in SIM mode are presented in Table 5. 

NOTE: Because the surrogate analytes are added at a single concentration level to the 

calibration standards, calibrate for each surrogate using an average response factor. 

10.1.9 FORCING ZERO – Forcing the calibration curve through the origin is not 

recommended. However, zero must be forced for method analytes (e.g., common 

laboratory contaminants) if they are consistently detected in the Laboratory Reagent 

Blanks. Forcing zero allows for a better estimate of the background level of blank 

contaminants. An accurate estimate of background contamination is necessary to set 

MRLs for method analytes when blank levels are problematic (Sect. 9.2.4). 

10.1.10 CALIBRATION ACCEPTANCE CRITERIA – The initial calibration is validated by 

calculating the concentration of the analytes for each of the analyses used to generate 

the calibration curve by use of the regression equations. Calibration points that are 

≤MRL must calculate to be within +50% of their true value. All other calibration 
 

524.3-28

points must calculate to be within +30% of their true value. If these criteria cannot be 

met, the analyst will have difficulty meeting ongoing QC criteria. In this case, 

corrective action is recommended such as reanalyzing the calibration standards, 

restricting the range of calibration, or performing instrument maintenance. 

10.2 CONTINUING CALIBRATION CHECKS (CCCs) – Analyze a CCC to verify the initial 

calibration at the beginning of each Analysis Batch, after every tenth field sample, and at the 

end of each Analysis Batch. The beginning CCC for each Analysis Batch must be at or below 

the MRL. This CCC verifies instrument sensitivity prior to the analysis of samples. Alternate 

subsequent CCCs between the remaining calibration levels. 

10.2.1 Calculate the concentration of each analyte in the CCC. Each analyte in the CCC 

fortified at ≤MRL must calculate to be within +50% of its true value. At all other 

levels, each analyte, including the surrogate analytes, must calculate to be within 

+30%. If these limits are exceeded, then all data for the failed analytes must be 

considered invalid. Any field samples analyzed since the last acceptable CCC that 

are still within holding time must be reanalyzed after an acceptable calibration has 

been restored. 

10.2.2 REMEDIAL ACTION – Failure to meet QC performance criteria for CCCs requires 

remedial action. Acceptable method performance may be restored simply by 

recalibrating in accordance with the guidelines in Section 10.1 and verifying 

sensitivity by analyzing a CCC at or below the MRL. Because of the volatile nature 

of the method analytes, Primary Dilution Standards have limited shelf life. Prepare a 

fresh PDS and repeat the CCC before contemplating instrument maintenance. If 

internal standard and calibration failures persist, maintenance such as extended bake 

cycles for both the purge-and-trap concentrator and the GC/MS, clipping the GC 

column, replacing the concentrator trap, and cleaning the MS source may be required. 

Following major maintenance, the analyst must return to the initial calibration step 

(Sect. 10.1). 

11. PROCEDURE

Important aspects of this analytical procedure include proper sample collection and storage 

(Section 8), ensuring that the instrument is properly calibrated (Section 10), and that all required 

QC elements are included (Section 9). This method is designed for a 5-mL sample volume. The 

concentration of the internal standards and surrogate analytes must be the same in the samples as 

in the calibration standards. In the laboratory, maintain field samples, QC samples, and calibration 

standards at or below 6 °C at all times while in storage. While resident in the autosampler 

awaiting analysis, samples must be maintained at less than or equal to 10 °C. Do not store samples 

in the autosampler longer than the time required to complete the Analysis Batch. 

11.1 SAMPLE PREPARATION: SYRINGE METHOD – For concentrators with a single 

sparging vessel and autosamplers with multiple sparging vessels, load the sample (or 

previously prepared calibration standard) by use of a 5-mL syringe. If the purge cycle will 

be initiated immediately after this step, warm the sample to room temperature. Remove the 

plunger from two syringes and attach a closed syringe valve. Open the VOA vial, and 

carefully pour the sample into the syringe barrel to just short of overflowing. Replace the 

syringe plunger, invert the syringe, and compress the sample. Open the syringe valve and 
 

524.3-29

vent any residual air while adjusting the sample volume to 5 mL. Add the internal 

standard/surrogate analyte PDS to the sample through the syringe valve. Immediately load 

the sample into the sparging vessel. 

NOTE: Do not store samples in syringes or prepare QC samples by filling two syringes. A 

second VOA vial (i.e., a Field Duplicate) is required as a means of ensuring that a back up 

sample is available, and for preparing FD, LFSM and LFSMD QC samples. 

11.1.1 PREPARATION OF LFSM and LFSMD: SYRINGE METHOD – Three 40-mL 

vials (FDs) are required for a sample and its associated LFSM and LFSMD. Fortify 

two of the samples using an analyte PDS of appropriate concentration by injecting 

through the syringe valve. Add the internal standards and surrogates as directed in 

Section 11.1. 

11.1.2 FIELD DUPLICATE: SYRINGE METHOD – Fill a 5-mL syringe with the selected 

Field Duplicate, and fortify with internal standards and surrogates. Analyze FDs at 

the frequency specified in Section 9.3.8. 

11.2 SAMPLE PREPARATION: VIAL AUTOSAMPLER METHOD – Activate the cooling 

mechanism of the refrigerated autosampler and allow it to reach the temperature set point. 

Remove samples from cold storage and immediately load them into the vial autosampler. 

Prepare the IS/surrogate fortification solution at a concentration appropriate for the 

automated standard addition device. 

11.2.1 PREPARATION OF LFSM and LFSMD FOR VIAL AUTOSAMPLERS – Three 

40-mL vials (FDs) are required for a sample and its associated LFSM and LFSMD. 

Fortify two of the samples using an analyte PDS of appropriate concentration by 

puncturing the septa of each vial with a syringe. Allow time for the compounds to 

disperse homogeneously within the sample. Assume that the sample volume is 40 

mL or estimate the typical volume of a 40-mL vial in use at your laboratory. 

Fortification may be accomplished by use of a standard addition module if the 

autosampler is so equipped. 

11.2.2 FDs FOR VIAL AUTOSAMPLERS – Load the appropriate Field Duplicate vial into 

the autosampler. Analyze FDs at the frequency specified in Section 9.3.8. 

11.3 PURGE-AND-TRAP ANALYSIS 

11.3.1 Establish purge-and-trap and GC/MS operating conditions per the guidance in 

Section 10.1. 

11.3.2 Bake the concentrator trap and GC column to remove contaminants that may have 

collected in the system. This step is especially important if the analytical system has 

been idle for more than a few hours. 

11.3.3 Initiate the purge cycle and autosampler sequence. After the purge cycle, preheat the 

trap as recommended by the manufacturer. Start the data acquisition at the 

beginning of the desorb cycle. Bake the trap, and rinse the sparging vessel and 

autosampler delivery lines using settings optimized to minimize sample carryover. 
 

524.3-30

NOTE: The method preservatives cause the water column in the sparging vessel to 

appear effervescent during the purge cycle. This is normal and no adverse effects 

occur as a result of the effervescence. 

11.4 THE ANALYSIS BATCH – Establish a valid initial calibration following the procedures 

outlined in Section 10.1 and confirm that the calibration is still valid by analyzing a CCC at 

or below the MRL as described in Section 10.2. Alternately, verify that an existing 

calibration, established for a previous Analysis Batch, is valid by analyzing a CCC at or 

below the MRL. Next, analyze an LRB. Continue the Analysis Batch by analyzing aliquots 

of field and QC samples at appropriate frequencies (Section 9.3), employing the optimized 

conditions used to acquire the initial calibration. Analyze a mid- or high-level CCC after 

every ten field samples and at the end each Analysis Batch. 

NOTE: Each Analysis Batch must begin with the analysis of a CCC at or below the MRL 

for each analyte that the laboratory intends to report, followed by the analysis of an LRB. 

This is true whether or not an initial calibration is analyzed. After 20 field samples, the lowlevel CCC and the LRB must be repeated to begin a new Analysis Batch. The acquisition 

start time of the mid-level CCC at the end of the Analysis Batch must be within 24 hours of 

the acquisition start time of the low-level CCC at the beginning of the Analysis Batch. 

Multiple Analysis Batches within a 24-hour period are permitted. Do not count QC samples 

(LRBs, FRBs, FDs, LFSMs, LFSMDs) when calculating the frequency of CCCs that are 

required during an Analysis Batch. 

12. DATA ANALYSIS AND CALCULATIONS

12.1 COMPOUND IDENTIFICATION – Establish an appropriate retention time window for each 

analyte to identify them in QC and field sample chromatograms. Base this assignment on 

measurements of actual retention time variation for each compound in standard solutions 

analyzed on the GC/MS over the course of time. The suggested variation is plus or minus 

three times the standard deviation of the retention time for each compound for a series of 

injections. The injections from the initial calibration and from the IDC (Sect. 9.2) may be 

used to calculate the retention time window. However, the experience of the analyst should 

weigh heavily on the determination of an appropriate range. 

12.1.1 At the conclusion of data acquisition, use the same software settings established 

during the calibration procedure to identify peaks of interest in the predetermined 

retention time windows. Initially, identify an analyte by comparison of its retention 

time with that of the corresponding analyte peak in a recent initial calibration 

standard or CCC. 

12.1.2 Some GC/MS programs use spectra matching criteria when collecting data in full 

scan mode based on the comparison of field sample spectra (after background 

subtraction if necessary) to a reference spectrum in the user-created database. This 

database should be created prior to conducting the IDC from spectra obtained for a 

mid-level to high-level calibration standard and updated as necessary. If available, 

this feature may be utilized as a secondary identification routine; however, the 

primary criterion must be based on the analyte retention time. 
 

524.3-31

12.2 COMPOUND CONFIRMATION FULL SCAN MODE – In general, all ions that are present 

above 30 percent relative abundance in the mass spectrum of the user-generated database 

must be present in the mass spectrum of the sample component and must agree within an 

absolute 20 percent of the relative abundance in the reference spectrum. For example, if an 

ion has a relative abundance of 30 percent in the standard spectrum, its abundance in the 

sample spectrum must be in the range of 10 to 50 percent. Some ions, particularly the 

molecular ion, are of special importance, and should be evaluated even if they are below 30 

percent relative abundance. 

NOTE: Compound identification is more challenging when sample components are not 

resolved chromatographically and produce mass spectra containing ions contributed by more 

than one analyte. When GC peaks obviously represent more than one sample component 

(i.e., broadened peak with shoulder(s) or valley between two or more maxima), appropriate 

analyte spectra and background spectra can be selected by examining individual spectra 

profiles during the peak to determine the characteristic ions. When analytes co-elute (i.e., 

only one GC peak is apparent), the identification criteria may be met but each analyte 

spectrum will contain extraneous ions contributed by the co-eluting compound. 

12.3 COMPOUND CONFIRMATION SIM MODE – In SIM mode, each confirmation ion should 

be present. For each analyte identified by retention time, the abundance of the confirmation 

ions relative to the quantitation ion should agree within an absolute 20 percent of the relative 

abundance in the spectrum taken from a recent calibration standard analyzed in SIM mode. 

For example, if an ion has a relative abundance of 30 percent in the calibration standard, its 

abundance in the sample spectrum should be in the range of 10 to 50 percent. 

12.4 COMPOUND QUANTITATION – Calculate analyte concentrations using the multipoint 

calibration established in Section 10.1. Report only those values that fall between the MRL 

and the highest calibration standard. 

12.4.1 Calculations must use all available digits of precision, but final reported 

concentrations should be rounded to an appropriate number of significant figures (one 

digit of uncertainty); this is typically two, and not more than three, significant figures. 

12.4.2 Prior to reporting data, the chromatograms must be reviewed for incorrect peak 

identification or improper integration. 

12.4.3 Prior to reporting data, the laboratory is responsible for assuring that QC 

requirements have been met and that any appropriate qualifier is assigned. 

12.5 EXCEEDING THE CALIBRATION RANGE – The analyst must not extrapolate beyond the 

established calibration range. If an analyte result exceeds the range of the initial calibration 

curve, dilute the Field Duplicate using reagent water containing the method preservatives. 

Re-inject the diluted sample. Incorporate the dilution factor into final concentration 

calculations. The resulting data must be annotated as a dilution, and the reported MRLs must 

reflect the dilution factor. 
 

524.3-32

13. METHOD PERFORMANCE

References to specific brands or catalog numbers are included as examples only and do not imply 

endorsement of the product. These references do not preclude the use of other vendors or supplies. 

13.1 PRECISION, ACCURACY AND DETECTION LIMITS – The method performance data 

presented in Section 17 were collected using a Tekmar Stratum Purge and Trap Concentrator 

with a Tekmar AQUATek 70 Vial Autosampler interfaced to an Agilent 6890 Plus GC and an 

Agilent 5973 MS. Table 2 lists the purge-and-trap conditions used to gather the method 

performance data presented in Section 17. GC/MS conditions for the Agilent system are 

presented in Table 3. Table 4 presents the quantitation ions employed in full scan mode 

appropriate for the Restek Rtx®-VMS column (no interference from overlapping peaks) for 

each analyte, internal standard, and surrogate analyte, suggested internal standard 

assignments, and observed retention times associated with the method performance results. 

Table 5 lists the method analytes for which method performance data were collected in the 

SIM mode; primary quantitation ions and internal standard references are provided. Single 

laboratory LCMRLs and DLs determined in full scan mode are listed in Table 6. Single 

laboratory precision and accuracy data obtained in full scan mode are presented for three 

water matrices: reagent water (Table 7), chlorinated (finished) ground water (Table 8), and 

chlorinated (finished) surface water (Table 9). LCMRLs and DLs obtained in SIM mode for 

selected method analytes are presented in Table 10. Single laboratory precision and accuracy 

data were collected in SIM mode for selected analytes in three water matrices: reagent water 

(Table 11), chlorinated (finished) ground water (Table 12), and chlorinated (finished) surface 

water (Table 13). Figure 1 depicts an extracted ion chromatogram of the method analytes that 

are gases at room temperature. Figures 2 and 3 are total ion chromatograms of the method 

analytes in reagent water and drinking water, obtained under the conditions employed during 

method development. 

13.2 SAMPLE STORAGE STABILITY STUDIES – An analyte storage stability study was 

conducted by fortifying the analytes (20 μg/L of each analyte) into a chlorinated surface water 

that was collected, preserved, and stored as described in Section 8. The average recovery of 

triplicate analyses, conducted on Days 0, 7, 14 are presented in Table 14. 

13.3 SECOND LABORATORY DEMONSTRATION – The performance of this method was 

demonstrated by five outside laboratories, with results similar to those reported in Section 17. 

The authors wish to acknowledge Tekmar (Teledyne Technologies Co.), OI Analytical, EST 

Analytical, Varian, Inc., and Underwriters Laboratories, Inc., for their contribution to the 

development of this method.

14. POLLUTION PREVENTION

14.1 For information about pollution prevention that may be applicable to laboratory operations, 

consult “Less is Better: Laboratory Chemical Management for Waste Reduction” available 

from the American Chemical Society’s Department of Government Relations and Science 

Policy, 1155 16th Street N.W., Washington, D.C., 20036, or on-line at 

http://www.ups.edu/x7432.xml. 
 

524.3-33

15. WASTE MANAGEMENT

15.1 The analytical procedures described in this method generate relatively small amounts of waste 

since only small amounts of reagents and solvents are used. The matrices of concern are 

finished drinking water or source water. However, the Agency requires that laboratory waste 

management practices be conducted consistent with all applicable rules and regulations, and 

that laboratories protect the air, water, and land by minimizing and controlling all releases 

from fume hoods and bench operations. In addition, compliance is required with any sewage 

discharge permits and regulations, particularly the hazardous waste identification rules and 

land disposal restrictions. For further information on waste management, see the publications 

of the American Chemical Society’s Laboratory Environment, Health & Safety Task Force on 

the Internet at http://membership.acs.org/c/ccs/publications.htm. Additional waste 

management information can be found in “Laboratory Waste Minimization and Pollution 

Prevention,” Copyright © 1996 Battelle Seattle Research Center, which can be located at 

http://www.p2pays.org/ref/01/text/00779/ch05.htm. 

16. REFERENCES

1. Winslow, S. D.; Pepich, B. V.; Martin, J. J.; Hallberg, G. R.; Munch D. J.; Frebis, C. P.; 

Hedrick, E. J.; Krop, R. A. Statistical Procedures for Determination and Verification of 

Minimum Reporting Levels for Drinking Water Methods. Environ. Sci. Technol. 2006; 40, 

281-288. 

2. Glaser, J.A.; Foerst, D.L.; McKee, G.D.; Quave, S.A.; Budde, W.L. Trace Analyses for 

Wastewaters. Environ. Sci. Technol. 1981; 15, 1426-1435. 

3. Occupational Exposures to Hazardous Chemicals in Laboratories, 29 CFR 1910.1450, 

Occupational Safety and Health Administration. 

4. Safety in Academic Chemistry Laboratories; American Chemical Society Publication; 

Committee on Chemical Safety: 7th Edition, 2003. 

5. Standard Practice for Sampling Water from Closed Conduits; ASTM Annual Book of 

Standards, Section 11, Volume 11.01, D3370-07; American Society for Testing and Materials: 

Philadelphia, PA, 2007. 
 

524.3-34

17. TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA

The conditions listed in the tables of this section were used to collect method performance data at EPA. 

They do not represent any form of guidance for acceptable parameter settings. Refer to the relevant 

sections of the method for guidance on optimizing and selecting purge-and-trap and GC/MS conditions. 

TABLE 1. 4-BROMOFLUOROBENZENE (BFB) MASS INTENSITY CRITERIA 

m/z Required Intensity (relative abundance)

95 Base peak, 100% relative abundance 

96 5 to 9% of m/z 95 

173 Less than 2% of m/z 174 

174 Greater than 50% of m/z 95 

175 5 to 9% of m/z 174 

176 Greater than 95% but less than 105% of m/z 174 

177 5 to 10% of m/z 176 

TABLE 2. PURGE AND TRAP CONDITIONS USED FOR METHOD PERFORMANCE 

RESULTS 

Parameter Conditionsa

Sample volume 5 mL 

Sample purge temperature Ambient 

Trap Tekmar #9 (proprietary sorbent materials) 

Purge cycle 40 mL/min for 11 min 

Condenser purge temperature 20 oC 

Dry purge 100 mL/min for 2 min 

Desorb preheat temperature 250 oC 

Desorb cycle 260 oC for 1.0 min 

Bake rinse cycles Sparging vessel and autosampler sample path rinsed twice 

Bake cycle 280 oC for 4 min @ 200 mL/min a The chromatograms presented in Figures 2 and 3 were obtained under these conditions. 
 

524.3-35

TABLE 3. GAS CHROMATOGRAPHY/MASS SPECTROMETRY (GC/MS) CONDITIONS 

FOR METHOD PERFORMANCE RESULTS 

Parameter Conditionsa

Column Restek Rtx®-VMS 30 meter, 0.25 mm i.d., 1.4 μm df

Inlet liner 1-mm i.d., deactivated glass 

Inlet conditions 30:1 split ratio, 200 °C, helium carrier gas, column flow rate: 0.9 

mL/min 

GC temperature program 45 °C for 4.5 min, 12 oC/min to 100 °C, hold 0 min, 25 °C to 240 °C, 

hold 1.32 min 

Solvent delay 1.5 min before activating filaments in the electron impact source 

MS source temperature 230 oC 

MS quadrupole temperature 150 °C 

GC/MS interface Direct, 240 oC 

Full scan window 1 m/z 47 to 300 (1.5 to 2.9 min) 

Full scan window 2 m/z 35 to 300 (2.9 min to 16 min) 

SIM parameters 100 msec dwell per ion, 2 to 4 ions per retention time window a The chromatograms presented in Figures 2 and 3 were obtained under these conditions. 

TABLE 4. RETENTION TIMES, RECOMMENDED QUANTITATION IONS, AND 

SUGGESTED INTERNAL STANDARD REFERENCES FOR FULL SCAN MODEa

Analyte Peak no. Fig.’s 2a, 2b, 2c RT Q-Ion ISb Reference 

dichlorodifluoromethane 1 1.79 85 1 

chlorodifluoromethane 2 1.82 51 1 

chloromethane 3 1.97 50 1 

vinyl chloride 4 2.04 62 1 

1,3-butadiene 5 2.05 54 1 

bromomethane 6 2.34 94 1 

trichlorofluoromethane 7 2.59 101 1 

diethyl ether 8 2.90 59 1 

1,1-dichloroethene 9 3.11 96 1 

carbon disulfide 10 3.15 76 1 

methyl iodide 11 3.28 142 1 

allyl chloride 12 3.65 76 1 

methylene chloride 13 3.79 84 1 

trans-1,2-dichloroethene 14 3.98 96 1 

methyl acetate 15 4.01 43 1 

methyl-t-butyl ether-d3 (surrogate #1) 16 4.10 76 1 

methyl-t-butyl ether (MtBE) 17 4.13 73 1 

t-butyl alcohol (TBA) 18 4.28 59 1 

diisopropyl ether (DIPE) 19 4.66 45 1 

1,1-dichloroethane 20 4.84 63 1 

t-butyl ethyl ether (ETBE) 21 5.18 59 1 

cis-1,2-dichloroethene 22 5.59 96 1 
 

524.3-36

Analyte Peak no. Fig.’s 2a, 2b, 2c RT Q-Ion ISb Reference 

bromochloromethane 23 5.85 128 1 

chloroform 24 5.96 83 1 

carbon tetrachloride 25 6.12 117 1 

tetrahydrofuran 26 6.17 72 1 

1,1,1-trichloroethane 27 6.22 97 1 

1,1-dichloropropene 28 6.38 110 1 

1-chlorobutane 29 6.45 56 1 

benzene 30 6.70 78 1 

t-amyl methyl ether (TAME) 31 6.86 73 1 

1,2-dichloroethane 32 6.97 62 1 

trichloroethene 33 7.44 132 1 

1,4-difluorobenzene (IS #1) 34 7.49 114 1 

t-amyl ethyl ether (TAEE) 35 7.75 59 1 

dibromomethane 36 7.96 93 1 

1,2-dichloropropane 37 8.09 63 1 

bromodichloromethane 38 8.18 83 1 

cis-1,3-dichloropropene 39 8.94 75 1 

toluene 40 9.22 92 2 

tetrachloroethene 41 9.65 166 2 

trans-1,3-dichloropropene 42 9.70 75 2 

ethyl methacrylate 43 9.87 69 2 

1,1,2-trichloroethane 44 9.87 83 2 

dibromochloromethane 45 10.04 129 2 

1,3-dichloropropane 46 10.14 76 2 

1,2-dibromoethane 47 10.27 107 2 

chlorobenzene-d5 (IS #2) 48 10.75 117 2 

chlorobenzene 49 10.76 112 2 

ethylbenzene 50 10.79 91 2 

1,1,1,2-tetrachloroethane 51 10.82 131 2 

m-xylene 52 10.92 106 2 

p-xylene 53 10.92 106 2 

o-xylene 54 11.29 106 2 

styrene 55 11.33 104 2 

bromoform 56 11.36 173 2 

isopropylbenzene 57 11.55 105 2 

4-bromofluorobenzene (surrogate #2) 58 11.78 95 3 

bromobenzene 59 11.87 156 3 

n-propylbenzene 60 11.88 91 3 

1,1,2,2-tetrachloroethane 61 11.95 83 3 

2-chlorotoluene 62 12.01 126 3 

1,3,5-trimethylbenzene 63 12.03 105 3 

1,2,3-trichloropropane 64 12.05 110 3 

4-chlorotoluene 65 12.14 91 3 

t-butylbenzene 66 12.28 134 3 
 

524.3-37

Analyte Peak no. Fig.’s 2a, 2b, 2c RT Q-Ion ISb Reference 

pentachloroethane 67 12.30 167 3 

1,2,4-trimethylbenzene 68 12.33 105 3 

sec-butylbenzene 69 12.41 105 3 

4-isopropyltoluene 70 12.51 119 3 

1,3-dichlorobenzene 71 12.59 146 3 

1,4-dichlorobenzene-d4 (IS #3) 72 12.64 152 3 

1,4-dichlorobenzene 73 12.65 146 3 

n-butylbenzene 74 12.83 134 3 

hexachloroethane 75 12.94 166 3 

1,2-dichlorobenzene-d4 (surrogate #3) 76 12.96 152 3 

1,2-dichlorobenzene 77 12.96 146 3 

1,2-dibromo-3-chloropropane 78 13.54 157 3 

hexachlorobutadiene 79 13.97 225 3 

1,2,4-trichlorobenzene 80 14.01 180 3 

naphthalene 81 14.23 128 3 

1,2,3-trichlorobenzene 82 14.36 180 3 

a These quantitation ions are appropriate for the column used to generate method performance data. The user must 

verify that the quantitation ions selected for their column are unique and free from interference due to overlapping 

method analytes. 

b

 IS = internal standard. 

TABLE 5. RETENTION TIMES, RECOMMENDED QUANTITATION IONS, 

CONFIRMATION IONS, AND SUGGESTED INTERNAL STANDARD REFERENCES FOR 

SIM MODE 

Analyte RT Q-Ion IS a Reference 

methyl-t-butyl ether-d3 (surrogate #1) 4.09 76 1 

1,4-difluorobenzene (IS #1) 7.47 114 1 

1,2-dibromoethane 10.26 107 2 

chlorobenzene-d5 (IS #2) 10.73 117 2 

4-bromofluorobenzene (surrogate #2) 11.77 95 3 

1,4-dichlorobenzene-d4 (IS #3) 12.63 152 3 

1,2-dichlorobenzene-d4 (surrogate #3) 12.95 152 3 

1,2-dibromo-3-chloropropane 13.53 157 3 

a

 IS = internal standard. 
 

524.3-38

TABLE 6. LOWEST CONCENTRATION MINIMUM REPORTING LEVELS (LCMRLs) AND 

DETECTION LIMITS (DLs) FOR FULL SCAN MODE 

 

Analyte LCMRL, μg/L DL Fortification, μg/L DL, μg/L 

dichlorodifluoromethane 0.064 0.025 0.016 

chlorodifluoromethane 0.11 0.025 0.022 

chloromethane 0.062 0.050 0.034 

vinyl chloride 0.092 0.050 0.029 

1,3-butadiene 0.086 0.025 0.013 

bromomethane 0.072 0.050 0.037 

trichlorofluoromethane 0.099 0.050 0.030 

diethyl ether 0.24 0.050 0.039 

1,1-dichloroethene 0.092 0.10 0.049 

carbon disulfide 0.057 0.10 0.031 

methyl iodide 0.12 0.10 0.050 

allyl chloride 0.13 0.050 0.035 

methylene chloride 0.25 0.25 0.14 

trans-1,2-dichloroethene 0.098 0.050 0.050 

methyl acetate 0.24 0.050 0.030 

methyl-t-butyl ether (MtBE) 0.035 0.025 0.020 

t-butyl alcohol (TBA) 0.13 0.10 0.046 

diisopropyl ether (DIPE) 0.059 0.050 0.014 

1,1-dichloroethane 0.064 0.050 0.020 

t-butyl ethyl ether (ETBE) 0.044 0.025 0.010 

cis-1,2-dichloroethene 0.12 0.050 0.042 

bromochloromethane 0.18 0.050 0.033 

chloroform 0.054 0.050 0.025 

carbon tetrachloride 0.098 0.050 0.044 

tetrahydrofuran 0.35 0.50 0.14 

1,1,1-trichloroethane 0.076 0.050 0.026 

1,1-dichloropropene 0.25 0.10 0.082 

1-chlorobutane 0.041 0.025 0.020 

benzene 0.030 0.025 0.017 

t-amyl methyl ether (TAME) 0.042 0.025 0.017 

1,2-dichloroethane 0.051 0.050 0.025 

trichloroethene 0.091 0.050 0.035 

t-amyl ethyl ether (TAEE) 0.076 0.050 0.016 

dibromomethane 0.096 0.050 0.045 

1,2-dichloropropane 0.065 0.050 0.018 

bromodichloromethane 0.073 0.050 0.014 

cis-1,3-dichloropropene 0.064 0.050 0.026 

toluene 0.053 0.050 0.024 

tetrachloroethene 0.081 0.10 0.036 

trans-1,3-dichloropropene 0.058 0.050 0.032 

ethyl methacrylate 0.053 0.050 0.030 

1,1,2-trichloroethane 0.14 0.050 0.048 

dibromochloromethane 0.14 0.050 0.027 

1,3-dichloropropane 0.10 0.050 0.030 

1,2-dibromoethane 0.059 0.025 0.018 
 

524.3-39

Analyte LCMRL, μg/L DL Fortification, μg/L DL, μg/L 

chlorobenzene 0.15 0.025 0.019 

ethylbenzene 0.085 0.025 0.010 

1,1,1,2-tetrachloroethane 0.062 0.050 0.029 

m- and p-xylene 0.069 0.025 0.020 

o-xylene 0.039 0.025 0.010 

styrene 0.11 0.025 0.011 

bromoform 0.15 0.10 0.040 

isopropylbenzene 0.059 0.025 0.011 

bromobenzene 0.049 0.025 0.020 

n-propylbenzene 0.070 0.025 0.0077 

1,1,2,2-tetrachloroethane 0.093 0.050 0.013 

2-chlorotoluene 0.20 0.025 0.023 

1,3,5-trimethylbenzene 0.076 0.025 0.015 

1,2,3-trichloropropane 0.16 0.10 0.050 

4-chlorotoluene 0.043 0.025 0.014 

t-butylbenzene 0.077 0.025 0.020 

pentachloroethane 0.13 0.050 0.043 

1,2,4-trimethylbenzene 0.040 0.025 0.015 

sec-butylbenzene 0.068 0.025 0.012 

4-isopropyltoluene 0.052 0.025 0.012 

1,3-dichlorobenzene 0.16 0.025 0.012 

1,4-dichlorobenzene 0.065 0.025 0.015 

n-butylbenzene 0.16 0.10 0.045 

hexachloroethane 0.24 0.10 0.069 

1,2-dichlorobenzene 0.066 0.025 0.019 

1,2-dibromo-3-chloropropane 0.27 0.10 0.063 

hexachlorobutadiene 0.19 0.10 0.062 

1,2,4-trichlorobenzene 0.053 0.025 0.013 

naphthalene 0.090 0.025 0.012 

1,2,3-trichlorobenzene 0.088 0.050 0.020 
 

524.3-40

TABLE 7. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.50, 

1.0 AND 10 μg/L IN REAGENT WATER FOR FULL SCAN MODE 

Fortified Conc. = 0.50 μg/L 

(n=7) 

Fortified Conc. = 1.0 μg/L 

(n=7) 

Fortified Conc. = 10 μg/L 

(n=7) 

Analyte Mean % Recovery RSDa Mean % Recovery RSD Mean % Recovery RSD 

dichlorodifluoromethane 115 5.6 91.7 8.5 106 6.2 

chlorodifluoromethane 109 3.8 101 9.2 103 7.7 

chloromethane 111 3.1 99.0 6.7 101 6.7 

vinyl chloride 108 6.1 94.9 8.1 110 7.7 

1,3-butadiene 113 5.9 98.8 8.0 115 7.6 

bromomethane 99.5 9.6 101 10 103 7.8 

trichlorofluoromethane 94.3 9.4 95.3 10 117 7.0 

diethyl ether 104 8.4 102 8.0 109 6.4 

1,1-dichloroethene 99.6 8.7 94.8 9.0 97.2 6.8 

carbon disulfide 99.4 3.8 96.4 8.9 98.5 6.6 

methyl iodide 106 4.3 94.0 7.5 104 6.3 

allyl chloride 92.8 6.9 95.7 9.8 93.4 5.8 

methylene chloride 113 4.3 106 5.6 96.3 6.2 

trans-1,2-dichloroethene 94.9 4.7 100 6.8 96.2 6.7 

methyl acetate 108 2.8 102 20 93.4 3.5 

methyl-t-butyl ether 

(MtBE) 102 2.0 101 6.4 91.3 4.9 

t-butyl alcohol (TBA) 103 8.1 97.7 4.3 82.9 2.2 

diisopropyl ether (DIPE) 96.8 1.7 98.0 2.4 97.9 1.1 

1,1-dichloroethane 98.6 3.6 98.3 7.2 96.2 6.3 

t-butyl ethyl ether (ETBE) 91.7 2.3 97.0 2.0 92.9 0.68 

cis-1,2-dichloroethene 97.7 3.7 99.5 8.9 93.8 6.1 

bromochloromethane 102 5.1 98.2 9.3 91.9 6.0 

chloroform 95.3 4.2 99.4 5.3 98.0 6.1 

carbon tetrachloride 89.0 2.5 93.9 7.6 92.3 5.3 

tetrahydrofuran 79.5 18 97.1 7.4 90.4 4.3 

1,1,1-trichloroethane 94.7 5.5 98.0 10 98.2 6.2 

1,1-dichloropropene 87.4 6.9 94.9 8.0 97.1 5.7 

1-chlorobutane 95.8 5.9 100 7.3 97.9 5.9 

benzene 100 2.7 99.4 7.8 96.5 6.3 

t-amyl methyl ether 

(TAME) 93.6 3.2 98.2 1.9 93.1 0.42 

1,2-dichloroethane 103 1.8 101 7.4 98.6 5.9 

trichloroethene 98.8 6.5 99.6 7.9 94.8 5.7 

t-amyl ethyl ether (TAEE) 90.7 2.9 95.0 2.5 91.8 1.0 

dibromomethane 99.6 2.4 99.9 6.9 92.6 5.8 

1,2-dichloropropane 101 4.3 99.6 8.9 93.3 5.9 

bromodichloromethane 96.3 3.5 97.1 8.7 92.8 6.4 

cis-1,3-dichloropropene 93.0 3.0 96.0 6.4 90.0 5.8 

toluene 92.7 4.0 99.2 9.6 95.2 4.8 

tetrachloroethene 90.3 5.8 98.8 8.8 99.7 3.1 

trans-1,3-dichloropropene 87.5 2.3 95.2 8.4 90.0 5.5 

ethyl methacrylate 103 3.9 102 7.2 94.4 5.0 

1,1,2-trichloroethane 102 3.1 101 7.3 92.0 4.9 

dibromochloromethane 89.5 2.7 95.0 7.9 86.1 5.6 

1,3-dichloropropane 99.4 3.6 101 9.5 94.8 4.9 

1,2-dibromoethane 101 4.0 101 7.9 90.8 5.1 

chlorobenzene 96.8 3.1 99.2 7.2 94.2 4.2 
 

524.3-41

Fortified Conc. = 0.50 μg/L 

(n=7) 

Fortified Conc. = 1.0 μg/L 

(n=7) 

Fortified Conc. = 10 μg/L 

(n=7) 

Analyte Mean % Recovery RSDa Mean % Recovery RSD Mean % Recovery RSD 

ethylbenzene 86.9 3.9 95.9 9.2 98.3 2.7 

1,1,1,2-tetrachloroethane 90.8 3.8 95.6 8.6 90.0 4.5 

m- and p-xylene 89.0 4.1 98.2 9.2 96.9 2.7 

o-xylene 92.1 3.6 98.3 8.3 94.4 3.2 

styrene 91.6 3.9 95.5 8.8 92.9 3.9 

bromoform 86.1 4.9 92.0 8.1 80.8 4.5 

isopropylbenzene 78.9 4.0 97.1 7.3 103 3.5 

bromobenzene 97.2 3.3 96.8 9.1 90.9 3.8 

n-propylbenzene 78.8 5.1 94.4 9.9 104 3.4 

1,1,2,2-tetrachloroethane 100 2.6 99.2 6.7 87.9 4.8 

2-chlorotoluene 79.7 3.2 92.0 8.5 95.4 2.3 

1,3,5-trimethylbenzene 75.8 3.5 93.1 9.0 101 3.3 

1,2,3-trichloropropane 88.1 5.5 96.1 9.9 89.6 4.7 

4-chlorotoluene 92.1 3.4 97.2 7.6 96.5 2.4 

t-butylbenzene 65.5 8.8 91.7 8.6 105 3.7 

pentachloroethane 78.5 3.3 84.6 8.4 77.5 6.3 

1,2,4-trimethylbenzene 84.3 5.2 94.7 8.1 99.3 3.2 

sec-butylbenzene 59.4 7.9 90.3 10 112 5.3 

4-isopropyltoluene 61.4 6.9 91.3 11 108 5.1 

1,3-dichlorobenzene 86.2 4.6 93.9 6.2 93.3 2.4 

1,4-dichlorobenzene 91.8 3.4 95.8 7.5 92.4 2.6 

n-butylbenzene 65.6 13.6 80.7 11 69.7 2.3 

hexachloroethane 86.7 10 107 8.6 116 4.1 

1,2-dichlorobenzene 94.0 1.4 96.3 8.3 92.0 2.6 

1,2-dibromo-3-

chloropropane 106 12 99.3 8.2 80.4 3.4 

hexachlorobutadiene 44.8 20 94.6 12 122 11 

1,2,4-trichlorobenzene 85.0 3.9 95.6 7.2 97.1 4.6 

naphthalene 59.5 4.5 75.2 7.5 86.9 4.0 

1,2,3-trichlorobenzene 87.5 4.3 96.6 6.6 95.9 4.6 

a

 RSD = relative standard deviation.
 

524.3-42

TABLE 8. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.50, 

1.0 AND 10 μg/L IN DRINKING WATER FROM A GROUND WATER SOURCEa FOR FULL 

SCAN MODE

Fortified Conc. = 0.50 

μg/L (n=7) 

Fortified Conc. = 1.0 

μg/L (n=7) 

Fortified Conc. = 10 

μg/L (n=7) 

Analyte 

Native 

Conc., μg/L 

(n=3) 

Mean % 

Recoveryb RSDc Mean % Recoveryb RSD Mean % Recoveryb RSD 

dichlorodifluoromethane N.D. 96.5 6.8 98.6 2.8 103 7.6 

chlorodifluoromethane N.D. 103 6.3 99.9 5.5 103 4.3 

chloromethane N.D. 97.4 6.8 98.4 3.5 105 5.9 

vinyl chloride N.D. 103 5.5 100 3.1 115 6.5 

1,3-butadiene N.D. 87.2 8.5 96.3 5.2 118 6.8 

bromomethane N.D. 103 5.8 107 5.6 109 8.9 

trichlorofluoromethane N.D. 101 6.1 98.5 3.2 116 7.0 

diethyl ether N.D. 98.2 8.1 99.7 5.0 114 3.7 

1,1-dichloroethene N.D. 95.2 4.3 96.9 5.7 98.2 6.0 

carbon disulfide N.D. 95.0 4.9 95.7 3.8 101 6.7 

methyl iodide N.D. 102 5.2 99.0 5.2 103 3.9 

allyl chloride N.D. 91.3 4.8 89.5 4.3 99.0 6.3 

methylene chloride N.D. 103 7.5 102 3.3 102 5.9 

trans-1,2-dichloroethene N.D. 87.3 7.7 91.2 4.0 101 6.1 

methyl acetate N.D. 89.4 8.5 92.0 7.0 98.3 3.0 

methyl-t-butyl ether 

(MtBE) N.D. 96.2 4.9 96.6 1.3 97.9 4.7 

t-butyl alcohol (TBA) N.D. 79.6 21 90.2 9.6 85.1 3.3 

diisopropyl ether (DIPE) N.D. 94.4 2.2 96.3 2.8 98.9 2.7 

1,1-dichloroethane N.D. 97.2 8.7 96.0 3.6 103 6.0 

t-butyl ethyl ether (ETBE) N.D. 92.9 3.6 94.2 2.6 96.8 1.9 

cis-1,2-dichloroethene N.D. 94.4 6.1 95.2 2.7 100 5.4 

bromochloromethane N.D. 91.4 4.7 96.8 4.5 98.5 5.3 

chloroform 10 d 2.4 d 1.7 96.3 3.8 

carbon tetrachloride N.D. 99.8 3.8 95.8 3.4 95.0 5.1 

tetrahydrofuran N.D. 97.9 8.0 90.9 8.9 92.3 7.3 

1,1,1-trichloroethane N.D. 97.9 4.0 95.3 3.7 99.5 5.8 

1,1-dichloropropene N.D. 85.7 6.8 92.1 5.2 99.6 6.1 

1-chlorobutane N.D. 89.0 3.0 92.2 3.9 103 5.8 

benzene N.D. 94.1 5.4 97.1 2.2 102 5.7 

t-amyl methyl ether 

(TAME) N.D. 101 28 92.1 2.3 96.5 2.0 

1,2-dichloroethane N.D. 95.4 4.6 98.7 2.5 104 4.5 

trichloroethene N.D. 91.6 6.4 92.0 2.7 98.5 6.0 

t-amyl ethyl ether (TAEE) N.D. 94.2 3.4 93.8 4.0 96.8 3.2 

dibromomethane N.D. 97.9 5.2 96.8 2.1 99.8 5.1 

1,2-dichloropropane N.D. 97.6 5.3 98.5 2.1 102 5.4 

bromodichloromethane 9.3 d 1.2 d 2.0 102 2.7 

cis-1,3-dichloropropene N.D. 100.0 3.2 97.0 2.6 100 5.1 

toluene N.D. 101 2.7 99.8 1.7 98.7 6.0 

tetrachloroethene N.D. 81.0 3.0 83.0 4.9 91.1 5.7 

trans-1,3-dichloropropene N.D. 94.1 3.0 93.4 3.0 95.5 5.2 

ethyl methacrylate N.D. 99.2 2.1 91.7 2.0 96.1 5.2 

1,1,2-trichloroethane N.D. 78.0 7.0 89.7 2.9 97.1 5.2 

dibromochloromethane 6.3 d 2.4 d 2.3 96.5 2.8 

1,3-dichloropropane N.D. 90.9 8.0 95.1 3.0 99.6 5.1 

1,2-dibromoethane N.D. 99.5 4.5 96.6 2.3 95.6 4.4 
 

524.3-43

Fortified Conc. = 0.50 

μg/L (n=7) 

Fortified Conc. = 1.0 

μg/L (n=7) 

Fortified Conc. = 10 

μg/L (n=7) 

Analyte 

Native 

Conc., μg/L 

(n=3) 

Mean % 

Recoveryb RSDc Mean % Recoveryb RSD Mean % Recoveryb RSD 

chlorobenzene N.D. 95.3 4.1 98.2 1.9 98.0 5.4 

ethylbenzene N.D. 97.0 5.1 96.0 3.2 100 6.0 

1,1,1,2-tetrachloroethane N.D. 98.5 4.1 95.8 2.6 95.5 4.6 

m- and p-xylene N.D. 97.4 4.8 95.7 3.3 98.7 6.1 

o-xylene N.D. 97.0 6.2 95.2 2.2 98.5 6.3 

styrene N.D. 99.3 4.9 94.9 3.4 97.6 5.5 

bromoform 1.1 d 4.4 78.1 3.5 87.7 3.7 

isopropylbenzene N.D. 94.0 4.1 95.0 3.6 98.9 6.2 

bromobenzene N.D. 98.1 3.2 95.6 3.6 99.9 5.3 

n-propylbenzene N.D. 95.7 4.8 96.0 2.8 103 6.0 

1,1,2,2-tetrachloroethane N.D. 97.4 5.7 102 1.7 99.0 4.5 

2-chlorotoluene N.D. 95.5 2.1 96.3 2.3 102 5.8 

1,3,5-trimethylbenzene N.D. 96.0 5.1 94.7 3.0 103 5.7 

1,2,3-trichloropropane N.D. 90.4 10 96.0 4.5 94.8 4.9 

4-chlorotoluene N.D. 97.8 4.0 96.2 3.6 103 5.3 

t-butylbenzene N.D. 90.3 6.2 97.1 4.1 103 6.2 

pentachloroethane N.D. 123 13 133 5.0 100 4.8 

1,2,4-trimethylbenzene N.D. 101 3.7 98.2 2.3 103 5.3 

sec-butylbenzene N.D. 95.6 5.1 96.4 3.6 101 6.6 

4-isopropyltoluene N.D. 98.5 3.5 96.3 3.0 100 6.7 

1,3-dichlorobenzene N.D. 93.1 4.5 96.5 4.0 99.6 5.8 

1,4-dichlorobenzene N.D. 91.5 6.0 96.7 2.2 99.7 5.1 

n-butylbenzene N.D. 98.0 2.9 94.6 5.3 99.1 7.1 

hexachloroethane N.D. 91.0 5.7 104 4.8 106 7.7 

1,2-dichlorobenzene N.D. 92.6 4.6 97.1 2.7 99.7 4.9 

1,2-dibromo-3-

chloropropane N.D. 108 11 96.0 2.6 89.1 2.9 

hexachlorobutadiene N.D. 96.5 5.8 94.5 6.1 90.1 8.3 

1,2,4-trichlorobenzene N.D. 99.3 4.0 94.6 3.7 96.0 4.9 

naphthalene N.D. 98.9 3.3 88.7 3.0 94.1 4.2 

1,2,3-trichlorobenzene N.D. 88.8 6.0 91.3 3.3 95.7 4.5 

a

 Ground water physical parameters: pH = 7.45; hardness = 308 milligrams/liter (mg/L) (as CaCO3); free chlorine = 

0.94 mg/L. 

b Recoveries corrected for native levels in the unfortified matrix. c RSD = relative standard deviation.

d Fortified at less than 1⁄2 the concentration in the native matrix. 
 

524.3-44

TABLE 9. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.50, 

1.0 AND 10 μg/L IN DRINKING WATER FROM A SURFACE WATER SOURCEa FOR FULL 

SCAN MODE 

Fortified Conc. = 0.50 

μg/L (n=7) 

Fortified Conc. = 1.0 

μg/L (n=7) 

Fortified Conc. = 10 

μg/L (n=7) 

Analyte 

Native 

Conc., μg/L 

(n=3) 

Mean % 

Recoveryb RSDc Mean % Recoveryb RSD Mean % Recoveryb RSD 

dichlorodifluoromethane N.D. 108 4.9 92.4 3.5 100 3.3 

chlorodifluoromethane N.D. 102 5.7 96.9 3.6 104 4.1 

chloromethane N.D. 104 2.4 99.0 6.0 103 2.8 

vinyl chloride N.D. 101 7.4 98.1 3.0 115 3.2 

1,3-butadiene N.D. 103 9.0 98.0 5.3 120 3.4 

bromomethane N.D. 97.9 9.6 102 3.1 112 2.1 

trichlorofluoromethane N.D. 99.7 7.7 95.3 6.5 118 2.9 

diethyl ether N.D. 94.3 10 97.8 5.5 119 1.9 

1,1-dichloroethene N.D. 104 5.4 94.8 3.4 97.5 2.6 

carbon disulfide N.D. 102 3.5 93.8 2.8 99.5 3.0 

methyl iodide N.D. 111 4.3 96.3 2.2 103 3.4 

allyl chloride N.D. 107 3.4 95.8 4.6 99.4 2.8 

methylene chloride N.D. 98.8 4.8 95.0 4.8 101 2.3 

trans-1,2-dichloroethene N.D. 95.9 6.8 94.6 3.8 99.4 3.1 

methyl acetate N.D. 94.5 14 92.7 5.6 91.4 14 

methyl-t-butyl ether 

(MtBE) N.D. 105 7.0 95.4 2.0 97.2 1.4 

t-butyl alcohol (TBA) N.D. 113 11 90.1 5.5 84.9 2.7 

diisopropyl ether (DIPE) N.D. 94.4 1.6 94.7 1.1 101 2.0 

1,1-dichloroethane N.D. 99.1 4.1 95.2 2.9 103 2.5 

t-butyl ethyl ether (ETBE) N.D. 92.7 3.1 95.6 1.6 98.8 1.7 

cis-1,2-dichloroethene N.D. 98.6 4.3 96.4 3.1 100 3.1 

bromochloromethane N.D. 96.7 3.1 95.7 5.0 97.9 2.0 

chloroform 16 d 8.3 d 1.9 80.9 1.8 

carbon tetrachloride N.D. 106 3.1 95.0 3.2 96.5 3.7 

tetrahydrofuran N.D. 108 18 95.3 6.2 91.6 2.7 

1,1,1-trichloroethane N.D. 102 4.3 94.8 2.6 98.8 2.9 

1,1-dichloropropene N.D. 97.4 6.0 94.9 3.4 99.0 2.1 

1-chlorobutane N.D. 100 4.7 93.7 3.4 103 2.9 

benzene N.D. 103 3.0 96.7 2.0 102 2.5 

t-amyl methyl ether 

(TAME) N.D. 92.1 1.8 92.8 1.1 98.2 1.1 

1,2-dichloroethane N.D. 99.9 3.7 95.8 3.7 105 1.3 

trichloroethene N.D. 100 4.5 94.0 2.4 98.0 2.5 

t-amyl ethyl ether (TAEE) N.D. 95.1 2.2 97.4 2.4 98.3 2.3 

dibromomethane N.D. 106 7.1 99.4 3.1 99.7 2.0 

1,2-dichloropropane N.D. 100 5.7 97.6 3.9 103 1.9 

bromodichloromethane 12 d 6.4 d 1.6 97.0 1.5 

cis-1,3-dichloropropene N.D. 105 3.0 97.5 3.2 100 1.9 

toluene N.D. 97.0 3.8 95.7 1.7 99.0 2.1 

tetrachloroethene N.D. 93.7 3.5 88.7 3.2 94.2 1.9 

trans-1,3-dichloropropene N.D. 102 2.6 95.6 2.1 96.3 2.4 

ethyl methacrylate N.D. 107 3.3 93.4 2.8 97.2 1.5 

1,1,2-trichloroethane N.D. 92.3 7.2 94.3 4.8 98.2 1.4 

dibromochloromethane 9.6 d 4.8 d 1.2 97.7 2.6 

1,3-dichloropropane N.D. 103 5.6 99.2 2.9 101 1.5 

1,2-dibromoethane N.D. 98.9 6.6 97.0 3.0 96.8 2.2 
 

524.3-45

Fortified Conc. = 0.50 

μg/L (n=7) 

Fortified Conc. = 1.0 

μg/L (n=7) 

Fortified Conc. = 10 

μg/L (n=7) 

Analyte 

Native 

Conc., μg/L 

(n=3) 

Mean % 

Recoveryb RSDc Mean % Recoveryb RSD Mean % Recoveryb RSD 

chlorobenzene N.D. 96.3 2.5 97.2 2.1 99.1 2.0 

ethylbenzene N.D. 99.9 3.8 96.5 2.4 102 2.4 

1,1,1,2-tetrachloroethane N.D. 110 4.1 99.6 4.0 97.0 1.8 

m- and p-xylene N.D. 94.1 2.5 94.0 2.5 100 2.2 

o-xylene N.D. 96.7 3.0 94.9 3.3 100 1.8 

styrene N.D. 105 2.9 97.0 2.3 98.8 1.7 

bromoform 1.7 d 7.5 92.6 3.7 90.8 2.2 

isopropylbenzene N.D. 98.2 2.7 95.7 3.4 102 2.2 

bromobenzene N.D. 99.4 2.6 95.7 5.2 99.1 1.3 

n-propylbenzene N.D. 97.0 3.8 94.2 2.9 105 1.2 

1,1,2,2-tetrachloroethane N.D. 106 5.3 98.4 2.3 96.9 1.4 

2-chlorotoluene N.D. 99.1 5.2 95.9 4.3 103 0.86 

1,3,5-trimethylbenzene N.D. 98.2 3.0 94.8 2.9 104 0.66 

1,2,3-trichloropropane N.D. 123 6.0 100 4.1 94.1 2.0 

4-chlorotoluene N.D. 97.9 3.7 96.2 5.1 104 0.75 

t-butylbenzene N.D. 99.4 5.8 99.8 5.6 104 0.73 

pentachloroethane N.D. 117 7.6 118 7.0 97.3 2.9 

1,2,4-trimethylbenzene N.D. 97.2 4.1 95.1 3.7 104 0.50 

sec-butylbenzene N.D. 96.7 2.7 94.9 4.0 105 1.4 

4-isopropyltoluene N.D. 90.2 4.1 91.4 4.1 103 1.1 

1,3-dichlorobenzene N.D. 96.8 4.3 97.0 2.8 99.9 0.65 

1,4-dichlorobenzene N.D. 92.0 2.6 94.3 3.8 99.2 1.3 

n-butylbenzene N.D. 87.1 6.5 89.3 5.2 101 1.9 

hexachloroethane N.D. 91.7 6.0 97.4 8.1 108 2.2 

1,2-dichlorobenzene N.D. 95.6 3.2 95.9 3.3 99.4 1.1 

1,2-dibromo-3-

chloropropane N.D. 113 7.3 90.8 6.1 86.5 2.4 

hexachlorobutadiene N.D. 96.4 3.9 91.5 4.7 96.4 1.2 

1,2,4-trichlorobenzene N.D. 99.1 4.6 93.6 4.8 96.8 1.1 

naphthalene N.D. 117 6.0 94.2 4.4 93.8 1.2 

1,2,3-trichlorobenzene N.D. 103 5.0 94.5 4.8 96.3 0.75 

a

 Surface water physical parameters: pH = 7.43; hardness = 154 milligrams/liter (mg/L) (as CaCO3); free chlorine = 

2.7 mg/L; total chlorine = 3.7 mg/L. 

b

 Recoveries corrected for native levels in the unfortified matrix. 

c

 RSD = relative standard deviation. 

d

 Fortified at less than 1⁄2 the concentration in the native matrix. 
 

524.3-46

TABLE 10. LOWEST CONCENTRATION MINIMUM REPORTING LEVELS (LCMRLs) 

AND DETECTION LIMITS (DLs) FOR SIM MODE 

Analyte DL Fortification, μg/L LCMRL, μg/L DL, μg/L 

1,2-dibromoethane 0.0020 0.0041 0.0010 

1,2-dibromo-3-chloropropane 0.0020 0.0017 0.0016 

TABLE 11. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.010, 

0.020 AND 0.10 μg/L IN REAGENT WATER FOR SIM MODE 

Fortified Conc. = 

0.010 μg/L (n=7) 

Fortified Conc. = 

0.020 μg/L (n=7) 

Fortified Conc. = 

0.10 μg/L (n=7) 

Analyte Mean % Recovery RSDa Mean % Recovery RSD Mean % Recovery RSD 

1,2-dibromoethane 84.5 5.8 91.1 3.2 87.9 2.2 

1,2-dibromo-3-

chloropropane 65.4 14 89.9 12 77.4 3.6 

a

 RSD = relative percent deviation. 

TABLE 12. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.010, 

0.020 AND 0.10 μg/L IN DRINKING WATER FROM A GROUND WATER SOURCEa

 FOR 

SIM MODE 

Fortified Conc. = 

0.010 μg/L (n=7) 

Fortified Conc. = 

0.020 μg/L (n=7) 

Fortified Conc. = 

0.10 μg/L (n=7) 

Analyte 

Native 

Conc., 

μg/L 

(n=3) 

Mean % 

Recovery RSDb Mean % Recovery RSD Mean % Recovery RSD 

1,2-dibromoethane 0.0001 85.1 4.9 91.7 4.0 92.6 2.9 

1,2-dibromo-3-chloropropane N.D. 99.4 9.6 107 12.7 96.8 4.5 

a

 Recoveries corrected for native levels in the unfortified matrix. 

b

 RSD = relative percent deviation. 

TABLE 13. PRECISION AND ACCURACY OF METHOD ANALYTES FORTIFIED AT 0.010, 

0.020 AND 0.10 μg/L IN DRINKING WATER FROM A SURFACE WATER SOURCEa

 FOR 

SIM MODE 

Fortified Conc. = 

0.010 μg/L (n=7) 

Fortified Conc. = 

0.020 μg/L (n=7) 

Fortified Conc. = 

0.10 μg/L (n=7) 

Analyte 

Native 

Conc., μg/L 

(n=3) 

Mean % 

Recovery RSDb Mean % Recovery RSD Mean % Recovery RSD 

1,2-dibromoethane 0.0001 106 6.2 88.1 2.5 90.0 3.0 

1,2-dibromo-3-

chloropropane 0.0009 87.5 14 72.1 6.3 85.6 3.0 

a

 Recoveries corrected for native levels in the unfortified matrix. 

b

 RSD = relative percent deviation. 
 

524.3-47

TABLE 14. SAMPLE HOLDING TIME DATA FOR METHOD ANALYTES FORTIFIED AT 

20 μg/L IN A CHLORINATED SURFACE WATERa (n=3 SAMPLES) 

Day 0 Day 7 Day 14 

Analyte 

Mean % 

Recovery RSDb Mean % Recovery RSD Mean % Recovery RSD 

dichlorodifluoromethane 110 2.2 107 2.5 111 3.9 

chlorodifluoromethane 112 2.0 109 0.63 107 0.87 

chloromethane 114 0.88 110 1.1 112 2.0 

vinyl chloride 117 0.99 113 1.6 116 0.87 

1,3-butadiene 116 1.3 106 1.9 105 4.6 

bromomethane 117 6.9 116 3.5 114 2.5 

trichlorofluoromethane 114 0.54 116 2.9 117 2.4 

diethyl ether 110 1.2 106 1.5 113 1.0 

1,1-dichloroethene 106 0.94 107 0.62 111 2.3 

carbon disulfide 108 0.58 106 1.9 107 3.0 

methyl iodide 106 1.3 106 0.33 101 0.93 

allyl chloride 108 0.57 100 0.73 101 1.0 

methylene chloride 106 0.17 106 0.55 108 0.92 

trans-1,2-dichloroethene 107 0.89 103 1.8 107 1.5 

methyl acetate 105 3.4 101 0.32 83.2 4.0 

methyl-t-butyl ether (MtBE) 104 0.92 101 0.049 105 0.79 

t-butyl alcohol (TBA) 105 3.2 104 2.9 105 1.8 

diisopropyl ether (DIPE) 107 0.71 109 0.72 109 0.65 

1,1-dichloroethane 109 1.0 108 0.82 111 0.74 

t-butyl ethyl ether (ETBE) 105 0.30 107 0.53 107 0.89 

cis-1,2-dichloroethene 106 0.66 105 0.67 108 0.71 

bromochloromethane 104 0.64 104 1.4 105 0.45 

chloroform 102 0.56 100 0.91 107 0.97 

carbon tetrachloride 108 1.4 109 1.2 116 2.2 

tetrahydrofuran 102 1.4 98.4 1.5 101 1.7 

1,1,1-trichloroethane 109 0.70 109 0.89 115 0.94 

1,1-dichloropropene 110 0.24 107 1.5 108 1.5 

1-chlorobutane 114 0.25 111 1.1 115 0.90 

benzene 108 0.63 106 1.2 109 0.57 

t-amyl methyl ether (TAME) 105 0.56 107 0.45 107 0.59 

1,2-dichloroethane 108 2.1 105 0.59 108 1.2 

trichloroethene 105 0.28 105 0.85 107 0.16 

t-amyl ethyl ether (TAEE) 107 0.31 108 0.73 107 0.69 

dibromomethane 106 1.5 105 0.42 107 0.33 

1,2-dichloropropane 108 0.48 106 0.21 109 0.78 

bromodichloromethane 105 0.85 104 1.2 109 1.2 

cis-1,3-dichloropropene 106 0.33 98.5 1.0 96.7 1.2 

toluene 109 1.3 108 0.46 110 1.2 

tetrachloroethene 110 2.4 106 1.1 111 2.7 

trans-1,3-dichloropropene 106 1.9 99.1 0.94 96.4 0.30 

ethyl methacrylate 108 1.4 104 0.56 105 1.5 

1,1,2-trichloroethane 105 1.8 103 0.93 106 2.1 

dibromochloromethane 104 0.99 104 0.98 107 0.98 

1,3-dichloropropane 108 1.0 104 0.10 106 1.2 

1,2-dibromoethane 104 1.7 104 1.3 106 0.72 

chlorobenzene 108 1.4 106 0.36 109 1.1 

ethylbenzene 115 1.1 110 0.33 116 1.4 

1,1,1,2-tetrachloroethane 106 1.6 106 0.35 110 0.92
 

524.3-48

Day 0 Day 7 Day 14 

Analyte 

Mean % 

Recovery RSDb Mean % Recovery RSD Mean % Recovery RSD 

m- and p-xylene 114 1.3 110 0.70 114 2.3 

o-xylene 113 0.83 109 0.87 115 0.79 

styrene 111 1.3 106 0.62 108 1.7 

bromoform 103 1.8 101 1.7 108 1.5 

isopropylbenzene 118 1.2 114 0.81 123 1.5 

bromobenzene 109 0.38 104 1.9 107 1.8 

n-propylbenzene 122 1.3 111 2.0 119 2.1 

1,1,2,2-tetrachloroethane 108 0.63 100 1.5 103 0.83 

2-chlorotoluene 115 0.65 107 1.9 112 2.1 

1,3,5-trimethylbenzene 121 1.2 111 1.4 120 1.7 

1,2,3-trichloropropane 106 1.6 102 2.5 102 1.4 

4-chlorotoluene 113 4.1 106 1.8 110 2.0 

t-butylbenzene 123 0.84 115 1.3 129 0.38 

pentachloroethane 109 2.2 103 3.0 112 0.47 

1,2,4-trimethylbenzene 120 0.99 110 2.0 118 1.5 

sec-butylbenzene 125 1.5 115 1.8 129 1.9 

4-isopropyltoluene 123 1.3 112 2.4 123 2.6 

1,3-dichlorobenzene 113 0.85 105 1.7 109 1.5 

1,4-dichlorobenzene 113 1.1 104 2.0 107 1.7 

n-butylbenzene 122 1.3 106 3.6 111 6.5 

hexachloroethane 123 0.42 115 0.82 132 1.6 

1,2-dichlorobenzene 111 0.82 104 1.7 108 1.0 

1,2-dibromo-3-

chloropropane 105 1.9 99.1 1.9 103 2.4 

hexachlorobutadiene 122 2.5 112 3.6 124 2.1 

1,2,4-trichlorobenzene 114 1.3 102 2.3 105 3.0 

naphthalene 112 0.77 103 1.0 107 2.1 

1,2,3-trichlorobenzene 114 0.53 103 1.7 108 2.0 

a

 Surface water physical parameters: pH = 7.43; hardness = 154 milligrams/liter (mg/L) (as CaCO3); free chlorine = 

2.7 mg/L; total chlorine = 3.7 mg/L. 

b

 RSD = relative percent deviation. 
 

524.3-49

TABLE 15. INITIAL DEMONSTRATION OF CAPABILITY (IDC) QUALITY CONTROL 

REQUIREMENTS 

Method 

Reference Requirement Specification and Frequency Acceptance Criteria 

Section 

9.2.1 

Demonstration of 

low system 

background 

Analyze a Laboratory Reagent Blank 

(LRB) prior to any other IDC steps. 

Demonstrate that all method analytes are 

<1⁄2 of the Minimum Reporting Level 

(MRL) and that possible interferences from 

reagents and glassware do not prevent the 

identification and quantitation of method 

analytes. 

Section 

9.2.1 

Test for system 

carryover 

Analyze an LRB after the high 

calibration standard during the IDC 

calibration. 

Demonstrate that the method analytes are 

<1⁄2 of the MRL. 

Section 

9.2.2 

Demonstration of 

precision 

Analyze 7 replicate Laboratory Fortified 

Blanks (LFBs) fortified near the 

midrange concentration. 

Percent relative standard deviation must be 

≤20%. 

Section 

9.2.3 

Demonstration of 

accuracy 

Calculate average recovery for replicates 

used in Section 9.2.2. 

Mean recovery within +20% of the true 

value. 

Section 

9.2.4 MRL confirmation 

Fortify and analyze 7 replicate LFBs at 

the proposed MRL concentration. 

Confirm that the Upper Prediction 

Interval of Results (PIR) and Lower PIR 

(Sect. 9.2.4.2) meet the recovery criteria. 

Upper PIR ≤150% 

Lower PIR ≥50% 

Section 

9.2.5 

Quality Control 

Sample (QCS) Analyze mid-level QCS. Results must be within +30% of the true value. 
 

524.3-50

 TABLE 16. ONGOING QUALITY CONTROL REQUIREMENTS 

Method 

Reference Requirement Specification and Frequency Acceptance Criteria 

Section 

10.1 Initial calibration 

Use the internal standard calibration 

technique to generate a linear or 

quadratic calibration curve. Use at 

least 7 standard concentrations. 

Validate the calibration curve as 

described in Section 10.1.10. 

When each calibration standard is 

calculated as an unknown using the 

calibration curve, the lowest level 

standard must be within +50% of the 

true value. All other points must be 

within +30% of the true value. 

Section 

9.3.1 

Laboratory Reagent 

Blank (LRB) 

Analyze one LRB with each Analysis 

Batch. 

Demonstrate that all method analytes 

are below 1⁄2 the Minimum Reporting 

Level (MRL), and that possible 

interference from reagents and 

glassware do not prevent identification 

and quantitation of method analytes. 

Section 

10.2 

Continuing Calibration Check (CCC) 

Verify initial calibration by analyzing 

a low-level CCC at the beginning of 

each Analysis Batch. Subsequent 

CCCs are required after every 10 field 

samples, and after the last field 

sample in a batch. 

The lowest level CCC must be within 

+50% of the true value. All other 

points must be within +30% of the 

true value. 

Results for field samples that are not 

bracketed by acceptable CCCs are 

invalid. 

Section 

9.3.5 Internal standard (IS) Internal standards are added to all 

standards and samples. 

Peak area counts for each IS must be 

within ±30% of the area in the most 

recent CCC, and ±50% of the average 

peak area in the initial calibration. 

Section 

9.3.6 Surrogate analytes 

Surrogates are added to all field 

samples and QC samples prior to 

analysis. 

70% to 130% recovery 

Section 

9.3.7 

Laboratory Fortified 

Sample Matrix 

(LFSM) 

Analyze one LFSM per Analysis 

Batch. Fortify the LFSM with 

method analytes at a concentration 

close to but greater than the native 

concentrations (if known). 

For analytes fortified at concentrations 

≤2 x the MRL, the result must be 

within +50% of the true value. All 

other analytes must be within +30% of 

the true value. 

Section 

9.3.8 

Laboratory Fortified 

Sample Matrix Duplicate (LFSMD) or 

Field Duplicate (FD) 

Analyze at least one LFSMD or FD 

with each Analysis Batch. 

For LFSMDs or FDs, relative percent 

differences must be ≤30% (≤50% if 

concentration ≤2 x the MRL.). 

Section 

9.3.9 

Field Reagent Blank 

(FRB) 

Analyze FRB if method analytes are 

detected in field samples (except 

disinfection byproducts). 

Qualify results of any analyte detected 

in both field samples and the FRB. 

Section 

9.3.10 

Quality Control 

Sample (QCS) 

Analyze mid-level QCS at least 

quarterly. 

Results must be +30% of the true 

value. 
524.3-51

Figure 1. Mass chromatograms of "gases." @ 40 μg/L.
524.3-52

Figure 2a. Reconstructed total ion chromatogram: 40-μg/L procedural calibration standard. See Table 4 for 

name cross reference. 
524.3-53

Figure 2b. Reconstructed total ion chromatogram: 40-μg/L procedural calibration standard. See Table 4 for 

name cross reference. 
524.3-54

Figure 2c. Reconstructed total ion chromatogram: 40-μg/L procedural calibration standard. See Table 4 for 

name cross reference. 
524.3-55

Figure 3. Reconstructed total ion chromatogram: method analytes fortified into drinking water @ 20 μg/L.