524.3-1 EPA Document # EPA 815-B-09-009

METHOD 524.3 MEASUREMENT OF PURG EABLE 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 WA TER AND DRINKING WATER
U. S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268524.3-2 METHOD 524.3

MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY CAPILLARY
COLUMN GAS CHROMATOG RAPHY/MASS SPECTROMETRY

1. SCOPE AND APPLICATION

1.1 This is a gas chromatography/mass spectrometr y (GC/MS) method for the determination of purgeable organic compounds in finished drin king waters. Discontinuous scanning modes such as selected ion monitoring (SIM) and selected ion storage (SIS) are permitted for determining selected analytes that are monitore d 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 Con centration 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 99-87-6524.3-3 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 75-65-0524.3-4 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 spiki ng concentration such th at the probability of spike recovery in the 50% to 150% range is at least 99%. Si ngle 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 laborato ry 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 determ ine 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 statistic ally calculated minimum concentration that can be measured with 99% confidence that th e reported value is greater than zero. 2 The DL is dependent on sample matrix, fortification conc entration, 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 instru mentation, and the in terpretation of the
associated data.

1.7 METHOD FLEXIBILITY – In recognition of technological advances in analytical instrumentation and techniques, the laborat ory is permitted to modify purge-and-trap parameters and the GC/MS conditions. B ecause the purge-and-trap technique has a significant number of analyst-chosen parame ters, and because it employs a procedural524.3-5 calibration, the authors have determined an accept able range of purge-and-trap conditions that may be used (Sect. 9.1) and a means by which to evaluate method modifi cations (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 processi ng time, but result in poor er 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 instrume ntation that is not properly optimized and maintained. Trihalomethanes (THMs) and other commonly occurri ng contaminants in drinking water must be analyzed in the full s can detection mode. In all cases where method modifications are proposed, the analyst must pe rform the procedures out lined in the Initial Demonstration of Capability (IDC, Sect. 9.2), ve rify 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 me thod, which supersedes the above general guidance.

2. SUMMARY OF METHOD

Headspace-free samples are collected in amber, gl ass 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 tr ansferred to a glass sparging vessel along with appropriate amounts of internal st andard and quality control com pounds. 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. A dditional water management techniques may be applied. The trap is heated and backflushed with he lium to transfer the analytes directly into a gas chromatographic inlet. The inlet is operated in th e 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 sp ectrometer for detection and quantitation. The method analytes are identi fied by comparing the acquired mass spectra and retention times to reference spectra and reten tion 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 obtaine d 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 Analys is Batch must also in clude all required QC samples, which do not contribute to the maximu m field sample total of 20. The required QC samples include:

Laboratory Reagent Blank (LRB), Continuing Calibration Check (CCC) Standards, Laboratory Fortified Samp le Matrix (LFSM), and Laboratory Fortified Sample Matrix Dupli cate or Field Duplicate (LFSMD or FD).524.3-6 3.2 CALIBRATION STANDARD – An aqueous solution of the me thod analytes prepared from the Primary Dilution Standard solution. The calibration standard solutions are used to calibrate the instrument response with respect to anal yte concentration.

3.3 CONTINUING CALIBRATION CHECK (CCC) – A calibration standard containing the method analytes, internal standards and surrogate analytes, which is an alyzed 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 approxi mately equal to the total flow rate through the GC inlet (mL/min).

3.5 DETECTION LIMIT (DL) – The minimum concentra tion 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 dete rmination (Sect. 9.2.6), and accurate quantitation is not expected
at this level.

3.6 DRY PURGE VOLUME – The total volume of pur ge 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 colle cted at the same time, shipped and stored under identical conditions. Method precision, including the contribution from sample collection procedures, is estimated from the anal ysis of FDs. For the purposes of this method, Field Duplicates are necessary to conduct repeat analyses if the or iginal field sample is lost, or to conduct repeat analyses in the case of QC failure s associated with th e analysis of the original field sample. Field Duplicates are used to prepare Laboratory Fortified Sample Matrix (Sect. 3.11) and Laboratory Fortifie d Sample Matrix Dup licate (Sect. 3.12) QC samples.

3.8 FIELD REAGENT BLANK (FRB) – An aliquot of reagent water th at 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 conditio ns, storage, preservati on, and all analytical procedures. The purpose of the FRB is to determin e if method analytes or other interferences are introduced into the samples during transport and storage.

3.9 INTERNAL STANDARD (IS) – A pure compound a dded 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. Th e 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 whethe r the sample matrix contributes bias to the524.3-7 analytical results. For this me thod, separate field samples are required for preparing fortified matrix so that sampling error is in cluded 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 Fi eld Duplicate to assess method precision and accuracy when the occurrence of the method analyt es 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 a liquot of reagent water containing the preservatives, internal standard s and surrogate analytes. The L RB is used to determine if the method analytes or interference s are introduced from the laborator y environment, the reagents or glassware. The LRB is also used to test for cross contaminati on in the purge-and-trap system.

3.14 LOWEST CONCENTRATION MINIMUM RE PORTING LEVEL (LCMRL) – The single laboratory LCMRL is the lowest spiking concen tration such that the probability of spike recovery in the 50% to 1 50% range is at least 99%. 1

3.15 MATERIAL SAFETY DATA SHEETS (MSDS) – Written information provided by vendors concerning a chemical’s toxicit y, health hazards, physical propert ies, fire and reactivity data, storage instructions, spill response procedures, and handling precautions.

3.16 MINIMUM REPORTING LEVEL (MRL) – The mini mum concentration that can be reported by a laboratory as a quantified value for the me thod analyte in a sample following analysis.
This concentration must meet the criteria defi ned in Section 9.2.4 and must be no lower than
the concentration of the lowest calibra tion standard for each method analyte.

3.17 PRIMARY DILUTION STANDARD (P DS) – A solution containing the method analytes (or internal standards and surrogate analytes) prep ared 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 tec hnique in which calibration standards are processed through the entire met hod, including sample preparati on, 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 sour ce external to the laboratory and different from the source of calibration standards. The pur pose of the QCS is to verify the accuracy of the primary calibration standards.524.3-8 3.22 REAGENT WATER – Purified water that does no t contain any measurable quantity of the method analytes or interfering co mpounds at or above 1⁄2 the MRL.

3.23 STOCK STANDARD SOLUTION (SSS) – A concen trated solution containing one or more of the method analytes that is prepared in th e 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 al iquot 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 samp le, they provide a means of assessing method performance for a specific purge-and-trap analysis cycle.

4. INTERFERENCES

4.1 SAMPLE CONTAINERS, SHIPPING AND ST ORAGE – Volatile organic compounds (VOCs) present in ambient air, shipping cont ainers, and in the laboratory environment may permeate the PTFE-lined septa of the sample vial s 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 Fi eld Reagent Blanks as described in Section
9.3.9.

4.2 PURGE AND TRAP SYSTEM – Commercially avai lable 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 ve ssel and optimizing the bake cycle and rinse cycle parameters. The potential for carryover in the purge-and-trap syst em 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 ac ceptance 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, pr epare aqueous standards and blanks in a laboratory environment isolated fr om ambient sources of VOCs.

4.3.2 METHANOL – Traces of ketones, methylene chloride, and other organic solvents could be present in methanol. Purge-and-tr ap-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 report ed to produce small amounts of VOCs, particularly with extended use. For exampl e, toluene may be detected the first time a trap is desorbed during a work shift. Fo r 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—inc luding the regulator—will concentrate on the sorbent trap. High-purity gas supp lies and high-purity gas regulators are recommended to minimize contamination from these sources. Purge gas filters should be regenerated or repl aced at the intervals speci fied by the manufacturers.

4.4 MATRIX INTERFERENCES – Matr ix interferences are caused by contaminants that are present in the sample. The extent of matrix in terferences will vary considerably from source to source depending upon the natu re of the water. The anal ysis of Laboratory Fortified Sample Matrix (Sect. 9.3.7) provides evidence fo r 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 hand ling of chemicals used in this method. 3 The OSHA laboratory standards can be found on line at http://www.osha.gov/SLTC/labor atories/standards.html . A reference file of MSDSs should be made available to all personnel invo lved 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 number s 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 or ganic analysis (VOA) vials fitted with PTFE-faced silicone septa and polypropylen e screw caps (I-Chem Cat. No. S146–0040 or equivalent). Prior to reuse, wash vials and septa (if not punctu red) 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 isol ated from ambient sources of VOCs.

6.2 MICRO SYRINGES – Suggested si zes 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 sy ringe valves with Luer ends (Supelco Cat. No. 20926 or equivalent) for use sealing purge -and-trap syring es (Sect. 6.3).524.3-10 6.5 VOLUMETRIC FLASKS – Class A, suggest ed sizes include 50, 100, and 200 mL for preparation of calib ration 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 stor age 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 samp le volume. A glass frit should be installed at the base of the sample chambe r so the purge gas passes through the water column as finely divided bubbles with a di ameter of less than 3 mm at the origin.

NOTE: Larger sparging vessels are not allo wed. 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 proporti onally. While the procedural calibration technique corrects for this, lower purging e fficiency decreases me thod precision. In addition, larger purge volumes could result in the transfer of more water vapor to the trap, placing increased demand on the effi ciency of moisture control devices.

6.8.2 SORBENT TRAP – Purge-and- trap manufacturers typical ly recommend specific sorbent traps for use with their instrument s. Any trap design is acceptable provided the data acquired meet all QC cr iteria described in Section 9.

NOTE: During method development studies, a tr ap containing Tenax, silica gel and
coconut charcoal in series e xhibited complete breakthrough of chlorodifluoromethane. A trap containi ng Tenax, silica gel and carbon molecular sieve (CMS) exhibited partial breakth rough for chlorodifluoromethane. Chlorodifluoromethane cannot be analyzed us ing this method if these traps and traps of similar design, containing Tenax, silica ge l and coconut charcoal, or Tenax, silica gel and CMS, are used.

6.8.3 TRANSFER LINE – Silcosteel ® , or equivalent, heated tran sfer 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 au tosamplers must be capable of maintaining samples at a temperature of 10 °C or lower. Verify the temperature of field samples placed in the autosample r using an external thermocouple or thermometer (inserted into a vial containi ng water) during the ID C 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 inco rporated 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 opti on 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/sp litless injector and a flow controller that is compatible with purge-and-trap analysis. In this configurati on, the purge-and-trap effluent is plumbed directly to the carrie r 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 deac tivated 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 volat ile 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 fragme nt 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 vo lts (eV) and must be operated in the positive ion mode. An ion-trap mass spect rometer, tuned to produce mass spectra that approximate standard, library spectra obtained under EI conditi ons, may be used. The instrument must be capable of obtaini ng 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 all524.3-12 criteria in Table 1 when 4-bromofluorobe nzene (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. Th e software must allow integration of the ion abundance of any specific ion between sp ecified time or scan number limits. The
software must also allow construction of lin ear or second-order re gression 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 Amer ican 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 ne gatively affecting data quality.

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

purge gas.

7.1.2 REAGENT WATER – Purified water whic h does not contain any measurable quantities of any method analytes or in terfering compounds at or above 1⁄2 the MRL for each compound of interest.

7.1.3 METHANOL (CH 3 OH, 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 (C 6 H 8 O 6 , CAS# 50-81-7) – Dechlorinating agent, demonstrated to be free of analytes and interferences (A lfa Aesar Cat. No. A15613 or equivalent).

7.1.5 MALEIC ACID (C 4 H 4 O 4 , CAS# 110-16-7) – Used as a preservative and to lower pH for the purpose of preventing dehydrohal ogenation of chlorinated analytes. High purity, demonstrated to be free of analytes and interferences (Sigma Cat. No. M0375 or equivalent).

7.1.6 SODIUM THIOSULFATE (Na 2 S 2 O 3 , CAS# 7772-98-7) – Optional dechlorinating agent when sampling only for THMs (Sig ma 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 ope ning the sealed ampoules , store commercial
mixes in micro-reaction vials wi th Mininert caps (Sect. 6.7) at a temperature of -10 °C or lower. After transfer, replace vendor-suppl ied, stock solutions within one month.524.3-13 NOTE: Methyl iodide may degrade fast er than other liquid analytes. Monitor the area of this compound relative to the internal standard, 1, 4-difluor obenzene. Replace the stock standard if methyl iodide shows evidence of degradation.

7.2.1 INTERNAL STANDARD STOCK SOLUTION S (ISSS) (1000 to 2500 μg/mL) –
This method uses three internal standa rds: 1,4-difluorobenzene (CAS# 540-36-3),
chlorobenzene- d 5 (CAS# 3114-55-4) and 1,4-dichlorobenzene- d 4 (CAS# 3855-82-1).

7.2.2 SURROGATE STOCK STANDARDS (SURSS ) (1000 to 2500 μg/mL) – This method uses three surrogate an alytes: methyl-t-butyl-ether- d 3 (CAS# 29366-08), BFB (CAS# 460-00-4) and 1,2-dichlorobenzene- d 4 (CAS# 2199-69-1).

NOTE: During method development, methyl-t-butyl-ether- d 3 was obtained as the neat compound (Aldrich Cat. No. 43413-2 or equivalent).

7.2.3 ANALYTE STOCK STANDARD SOLUTIONS – Ob tain the analytes listed in the
table in Section 1.1 as certified mixes in meth anol, 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 revisi on 524.3) were obtained as custom mixes in
methanol.

7.2.4 PREPARATION INSTRUCTIONS FOR LIQU ID 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-a nd-trap-grade methanol. To achieve the 10 mg/L nominal concentration, calculat e the volume of the liquid analyte corresponding to 200 mg. Care fully 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 th e exact solution concentration. When a compound’s purity is assayed to be 96 per cent or greater, the we ight can be used
without correction to calc ulate the concentration of the stock standard.

7.2.5 PREPARATION INSTRUCTIONS FOR SOLI D 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 di fficult to transfer materials, insert the entire weigh boat into a VOA vial containi ng 20-mL of methanol. If the measured mass of analyte is not exactly 200 mg, adju st 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 us ed 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. St ock 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 SU RROGATE 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 in ternal 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 initia l calibration, e.g., 5 μg/L in full scan mode and 0.5 μg/L in SIM mode is recommended. Stor e 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 (ana lyte PDS) – The analyte PDS is used to prepare the calibration standards and to fortify LFBs, LFSMs and LFSMDs with the method analytes. The analyte PD S is prepared by combining appropriate volumes of the analyte stock standard solutio ns to achieve concentrations appropriate for preparing aqueous calibration standa rds 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 micr o-reaction vials with Mininert caps at a temperature of -10 °C or colder. PDS solu tions 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 procedur al calibration standa rds 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 c onstant concentration of each internal standard and surrogate analyte is added to each calibrati on standard, either ma nually or by use of an automated standard addition module (Sect. 6.8.6) . The lowest concen tration calibration
standard must be at or below the MRL. Th ese calibration standards may also be used as
CCCs. The dilution schemes for calibration stan dards 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:

CAL a 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 calibrati on 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, PRES ERVATION, AND STORAGE

8.1 SAMPLE COLLECTION

8.1.1 Prior to shipment to the field, maleic and as corbic acid must be added to each sample bottle. Cap the vials tightly to avoid spillag e 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 male ic acid in the sample containers are 0.625 g/L and 5 g/L, respectively. Using narrow-ra nge 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. Coll ect another sample for that location, but do not add the method preservatives. Document these samples as “not acidified.” Unpreserved samples must be analyz ed 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 sa mple collection. Do not add ascorbic or maleic acid when employi ng this preservation option.

NOTE: If the residual chlorine is likely to be present at greater than 5 mg/L, a
determination of the chlorine concentrati on 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 acco rdance 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 temperatur e 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 bubbl es should pass through the sample as the bottle is filled, or be trapped in th e sample when the bottle is sealed.

8.1.5 When sampling from an open body of water, f ill 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 sampli ng kits. Do not open FRBs in the field; FRBs must remain sealed until analysis.

8.2.2 Use the same procedure to prepare samp le 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 minimu m, collect all samples in dup licate. If the samples will be analyzed using a vial autosampler, colle ct 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 mu st 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 receive d at the laboratory. In the laboratory, samples must be stored at or below 6 °C, protected fr om light, and isolated from ambient sources of VOCs. When resident in the autosampler, sample s 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 Demonstrati on of Capability and ongoing QC requirements. This section describes each QC parameter, its re quired frequency, and the pe rformance criteria that must be met in order to satisfy EPA quality objec tives. The QC criteria discussed in the following
sections are summarized in Secti on 17, Tables 15 and 16. These QC requirements are considered the minimum acceptable QC criteria. Laboratorie s are encouraged to institute additional QC practices to meet their specific needs. Complia nce 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 instrume ntation. However, five key parameters are restricted to prescribed ranges. These range s are summarized in the table below. If the chosen parameters fall within the “recommende d” 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 para meters 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 para meters 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-tra p concentrators, vary ing in design and water management systems, were evaluate d to determine these minimum and maximum parameter settings. The “recommended” values provided equivalent response factors and internal standard areas within the ranges sp ecified in the table. The “allowable” limits
resulted in a wider variation in response factors, part icularly for those analytes with low purge efficiencies; however, operation wi thin this range may be appropr iate for limited analyte lists and other concentrator designs. Sample temp erature 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 exampl e, 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, re peat 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 BA CKGROUND – Analyze an LRB.
Confirm that the blank is free of cont amination as defined in Section 9.3.1.

NOTE: The method must be checked fo r carryover by analyzing an LRB immediately following the highest calibration st andard. If this LRB does not meet the criteria outlined in Section 9.3.1, then carr yover is present and the cause must be
identified and eliminated.

9.2.2 DEMONSTRATION OF PRECISION – Prepar e and analyze seven replicate LFBs. Fortify these samples near the midrange of the initial calibration curve. The method preservation reagents must be added to th e LFBs as described in Section 8.1. The percent relative standard de viation (RSD) of the concen trations of the replicate analyses must be ≤ 20% for all method analytes.

100 ion Concentrat Average ions Concentrat Measured of Deviation Standard RSD % × =

9.2.3 DEMONSTRATION OF ACCURACY – Calcul ate the average percent recovery using the same set of replicat e data generated for Section 9. 2.2. The average recovery of the replicate analyses must be within + 20% of the true value.

100 ion Concentrat Fortified ion Concentrat Measured Average 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 concen tration too low may cause repeated failure of ongoing QC requirements. Confirm the MRL fo llowing the procedure outlined below.

NOTE: Method analytes that are consiste ntly present in the background (e.g., methylene chloride, TBA) should be reported as detected in field samples only after careful evaluation of the background leve ls. In such cases, an MRL must be
established at a value no less than three tim es 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 in tended 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 ( HR PIR ) using the equation below

HR PIR = 3.963 S524.3-19 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 + HR PIR ) 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 crit eria are not met, the MRL has been set too low and must be confirmed ag ain 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 accura cy 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 monito ring. It is the responsibility of the laboratory to ascertain whether DL de termination is required based upon the intended use of the data.

Analyses for this procedure must be done ove r 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 pres ervatives must be added to the samples as
described in Section 8.1. Pr ocess the seven replic ates 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% c onfidence level with n-1 degrees of freedom (for seven replicate dete rminations, 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 – Th is section describes the ongoing QC procedures that must be followed when processing and analyzin g field samples. Table 16 summarizes these requirements.

9.3.1 LABORATORY REAGENT BLANK (LRB) – An alyze an LRB with each Analysis
Batch. The LRB must contai n the method preservatives, th e internal standards, and surrogate analytes at the same concentra tion used to fortify all field samples and calibration standards. Background from met hod analytes or contam inants 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 an alyte(s) must be cons idered 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 cont amination 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 exceed ed the calibration range in the previous sample are detected at or above the MRL, these sample s are invalid. If the affected analytes do not exceed the MR L, these subsequent samples are valid. THMs are excluded from this requirement.

NOTE: The LRB test in the IDC may be par ticularly 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 ar e fortified reagent waters, there is no
difference between the LFB and the CCC standa rds. 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 c onducting 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 mu st 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 co rresponding 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 re sults 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 decr ease 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 fortificatio n technique. Perform the appropriate instrument maintenance and then reanaly ze the sample (Field Duplicate) in a subsequent Analysis Batch. If the IS area fails to meet the acceptance criteria in the Field Dupl icate, 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 pr ior to purge-and-trap analysis. Calculate the percent recovery (%R) for each su rrogate using the following equation:

100 B A %R × ⎟ ⎠ ⎞ ⎜ ⎝ ⎛

=

where A = calculated surrogate concentrati on 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 ra nge 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 solu tion and the fortification technique, 3) contamination, and 4) instrument calibration. Also, see corrective action options in Section 9.3.5.2. Correct th e 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 surroga te recovery criterion, only report data for the Field Duplicate.

9.3.6.3 If the Field Duplicate fails the surrog ate 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 Fiel d 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 nati ve background concentration, if known. Selecting a duplicate aliquot of a sample that has already be en analyzed aids in the selection of an appropriate spiking level. If this is not possible, use
historical data and rotate thr ough low, medium, and high calibration
concentrations when selecti ng a fortifying concentration.

NOTE: If the presence of disinfecti on byproducts (DBPs) (e.g., THMs) precludes selection of an appropriate fortification level for the majority of the method analytes, the DBPs may be i gnored. 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 B

- A %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 MR L 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 la boratory performance for that analyte is shown to be in control in the CCCs, th e recovery is judged matrix biased. The result for that analyte in the unfortified sample is labeled “suspect/matrix.”

NOTE: In order to obtain meaningful pe rcent 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 LABORATO RY FORTIFIED SAMPLE MATRIX DUPLICATE (FD or LFSMD) – Within each Analysis Batch, analyze a minimum of one Field Duplicate or one Laboratory Fortif ied Sample Matrix Duplicate. If method analytes are not routinely observed in fiel d samples, analyze an LFSMD rather than
an FD.

9.3.8.1 Calculate the relative percent differe nce (RPD) for duplicate measurements (FD 1 and FD 2 ) using the equation:



## ( ) 100 /2 FD FD FD

FD RPD

2 1 2

1 × +

−

=

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 ti mes the MRL concentration). At these concentrations, Field Duplicates must have RPDs that are ≤ 50%. If the RPD of an analyte falls outside th e designated range, and the laboratory performance for the analyte is in contro l 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 /2 LFSMD LFSM LFSMD

LFSM RPD × +

−

=524.3-24 9.3.8.4 RPDs for duplicate LFSMs must be ≤ 30%. Greater vari ability may be
observed when fortified LFSMs have anal yte concentrations that are near or at the MRL (within a fact or 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 mu st 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 de tected 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 mu st 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 accu racy for any analyte fails the recovery criterion, check the standard preparation process, stock standard sources, and the purity of neat materials used to prepare th e stock standards to locate and correct the problem.

9.4 METHOD MODIFICATION QC REQUI REMENTS – The analyst is permitted to modify the five key purge-and-trap parameters (sample te mperature, purge flow rate, purge volume, desorb time, and dry purge volume) selecti ng values outside of the “recommended” ranges (Sect. 9.1). The analyst is not permitted to modi fy sample collection and preservation, change the QC requirements of the method, or increas e the sample volume above 5 mL. Do not add or delete QC compounds from the list prescrib ed in the method: ISs (Sect. 7.2.1) and surrogates (Sect. 7.2.2). Each time method modifi cations are proposed for one of the five key parameters; that is, outside of the “reco mmended” 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 conditi ons that fall within the “recommended” ranges as presented in Section 9.1. Dete rmine relative response factors (RRF) for each analyte averaged over the entire calibration range.


## ( ) ( ) ( ) (μg/L) Analyte area IS μg/L IS area Analyte RRF

× ×

=

9.4.3 Optimize the purge-and trap system usi ng the proposed method modifications. Analyze three mid-level calibration standa rds and calculate mean RRFs for each524.3-25 method analyte. If all of the response f actors observed using th e modified conditions

are ≥ 70% of the initial ca libration 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 matr ices. If, for example, the laboratory analyzes drinking water from both surf ace 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 (CaCO 3 ) 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 independe ntly assessed by the labora tory’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 failu res are noted, the modification must be
abandoned.

10. CALIBRATION AND STANDARDIZATION

Demonstration and documentation of acceptable anal yte calibration is required before performing the IDC (Sect. 9.2) and prior to analyzing field samples. Verificat ion 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 calibra tion 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 matche d to the proper calibration and QC results. For example, fluorobenzene could be added to all sa mples 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 calib ration curve. Calibration must be performed using peak areas and the internal standard te chnique. Calibration using peak heights and external standard calibration are not permitted.524.3-26 10.1.1 MS TUNE/MS TUNE CHECK– Calibrate th e mass and abundance scales of the MS utilizing calibration compounds and proce dures 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 evalua te the performance of the system. Appropriate background subtraction is a llowed; 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, th e MS must be retuned to meet all criteria before proceeding with the initial calibration.

10.1.2 PURGE-AND-TRAP CONDITI ONS – Establish purge-and-trap parameters following the manufacturer’s recommendati ons. 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 operati ng conditions appropriate for the GC column dimensions by optimizing the split ra tio and temperature program. Generally, the required split ratio is inversely proportio nal 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 tr ansmission from the purge-and-trap concentrator. The split ratio will also aff ect the chromatographic peak profile of the most volatile method analytes, commonly re ferred 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 resolu tion of the method analytes as defined in the following subsections.

10.1.3.1 If possible, optimize chromatographi c conditions such that a unique quantitation ion is available for each an alyte 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 identi cal 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 anal ytes, 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 ma trix components in the baseline.

10.1.5 SIM MS CONDITIONS – In SIM mode, choos e one primary quantitation ion and at least one secondary ion. If possible, sele ct a second confirmation ion. Additional524.3-27 ions may be monitored that demonstrate a unique characteristic in the mass spectrum such as a halogen cluster. Verify that th e primary ion is free from interference (Sect. 10.1.3.1 and Sect. 10.1.3.2) due to an id entical 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 anal yte elutes entirely within the proper window during each Analysis Batch. Make this observation by viewing the mass chromatogram of the quantitat ion 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 cal ibration standards
as described in Section 7.4. The lowest concentration of th e calibration standards
must be at or below the MRL. The MR L 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 ca libration curve that spans the same concentration range used to collect the ID C 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 th e 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 devel opment was calibrated using inverse concentration-weighted quadrat ic curves. Suggested inte rnal 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 adde d at a single concentration level to the calibration standards, calibrate for each su rrogate using an average response factor.

10.1.9 FORCING ZERO – Forcing the calibrati on curve through the origin is not recommended. However, zero must be forced for method analytes (e.g., common laboratory contaminants) if they are consis tently detected in the Laboratory Reagent Blanks. Forcing zero allows for a better estimate of the background level of blank
contaminants. An accurate estimate of b ackground contamination is necessary to set MRLs for method analytes when blank levels are problematic (Sect. 9.2.4).

10.1.10 CALIBRATION ACCEPTANCE CRITERIA – Th e initial calibration is validated by calculating the concentration of the analytes fo r 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 calibration524.3-28 points must calculate to be within + 30% of their true value. If these criteria cannot be met, the analyst will have difficulty m eeting ongoing QC criteria. In this case,
corrective action is recommended such as reanalyzing the calib ration 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 Batc h, after every tenth field sample, and at the end of each Analysis Batch. The beginning CCC fo r each Analysis Batch must be at or below
the MRL. This CCC verifies instrument sensitivit y prior to the analysis of samples. Alternate subsequent CCCs between the remaining calibration levels.

10.2.1 Calculate the concentration of each analyt e 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 al l data for the failed analytes must be considered invalid. Any field samples an alyzed since the la st acceptable CCC that are still within holding time must be rean alyzed after an accep table 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 Sta ndards have limited shelf life. Prepare a fresh PDS and repeat the CCC before contem plating instrument maintenance. If
internal standard and calibra tion failures persist, maintenance such as extended bake cycles for both the purge-and-trap concen trator 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 ini tial calibration step (Sect. 10.1).

11. PROCEDURE

Important aspects of this analytical procedur e include proper sample collection and storage (Section 8), ensuring that the inst rument is properly calibrated (Sect ion 10), and that all required QC elements are included (Section 9). This met hod is designed for a 5-mL sample volume. The
concentration of the internal sta ndards 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 le ss than or equal to 10 °C. Do not store samples in the autosampler longer than the time re quired 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 barre l to just short of ove rflowing. Replace the syringe plunger, invert the sy ringe, and compress the sample. Open the syringe valve and524.3-29 vent any residual air while adjusting the sa mple 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 pr epare QC samples by filling two syringes. A second VOA vial (i.e., a Field Dupl icate) is required as a mean s 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 concentr ation by injecting through the syringe valve. A dd the internal standards and surrogates as directed in
Section 11.1.

11.1.2 FIELD DUPLICATE: SYRINGE METHOD – F ill 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 AUTOSAMP LER METHOD – Activate the cooling mechanism of the refrigerated autosampler and a llow it to reach the temperature set point. Remove samples from cold storage and immediat ely load them into the vial autosampler. Prepare the IS/surrogate fortification solu tion 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 anal yte PDS of appropriate concentration by puncturing the septa of each vial with a syringe. Allow time for the compounds to disperse homogeneously with in 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 us e of a standard addition module if the autosampler is so equipped.

11.2.2 FDs FOR VIAL AUTOSAMPLERS – Load the a ppropriate 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 ope rating conditions pe r 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 sequ ence. After the purg e cycle, preheat the trap as recommended by the manufacturer . Start the data acquisition at the beginning of the desorb cycle. Bake th e 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 wate r 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 in itial calibration follo wing the procedures
outlined in Section 10.1 and confirm that the ca libration is still valid by analyzing a CCC at
or below the MRL as described in Section 10. 2. Alternately, veri fy that an existing calibration, established for a pr evious Analysis Batch, is valid by analyzing a CCC at or below the MRL. Next, analyze an LRB. Con tinue the Analysis Batch by analyzing aliquots of field and QC samples at appropriate fre quencies (Section 9.3), employing the optimized conditions used to acquire the initial calibra tion. 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 calibrati on is analyzed. After 20 field samples, the lowlevel CCC and the LRB must be repeated to be gin a new Analysis Batch. The acquisition
start time of the mid-level CCC at the end of th e 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 peri od 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 – Es tablish 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 vari ation 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 re tention 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 retenti on time window. However, the e xperience 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 procedur e to identify peaks of inte rest in the predetermined
retention time windows. Init ially, identify an analyte by comparison of its retention time with that of the corresponding analyt e 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 us er-created database. This database should be created prior to co nducting 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 seconda ry 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-g enerated database must be present in the mass spectrum of the sample component and must agree within an absolute 20 percent of the rela tive 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 sh ould be evaluated even if they are below 30 percent relative abundance.

NOTE: Compound identification is more challe nging when sample components are not resolved chromatographically and produce mass sp ectra containing ions contributed by more than one analyte. When GC peaks obviously represent more than one sample component (i.e., broadened peak with shoul der(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 dete rmine the characteristic ions. When analytes co-elute (i.e., only one GC peak is apparent), the identific ation 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 re tention time, the abundance of the confirmation ions relative to the quantitation ion should agree within an absolute 20 per cent 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 abundan ce 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 – Ca lculate analyte concentra tions using the multipoint
calibration established in Secti on 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 appr opriate 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 chromatogram s 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 a ny appropriate qualifier is assigned.

12.5 EXCEEDING THE CALIBRATION RANGE – The analyst must not extrapolate beyond the established calibration range. If an analyte resu lt exceeds the range of the initial calibration curve, dilute the Field Duplic ate using reagent water containi ng the method preservatives. Re-inject the diluted sample. Incorporate th e dilution factor into final concentration calculations. The resulting data must be annotat ed as a dilution, and the reported MRLs must
reflect the dilution factor.524.3-32 13. METHOD PERFORMANCE

References to specific brands or catalog number s 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 LI MITS – 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 inte rfaced 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 employe d in full scan mode appropriate for the Restek Rtx ® -VMS column (no interference from overlapping peaks) for each analyte, internal standard, and surroga te analyte, suggested internal standard assignments, and observed retention times associ ated with the method performance results. Table 5 lists the method analytes for which me thod 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 (finishe d) 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 Tabl e 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 a nd 3 are total ion chromatograms of the method analytes in reagent water and drinking wate r, obtained under the c onditions 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 desc ribed in Section 8. The average recovery of triplicate analyses, conduc ted on Days 0, 7, 14 are presented in Table 14.

13.3 SECOND LABORATORY DEMONSTRATION – Th e performance of this method was demonstrated by five outside laboratories, with re sults similar to those reported in Section 17. The authors wish to acknowledge Tekmar (Tel edyne Technologies Co.), OI Analytical, EST Analytical, Varian, Inc., and Underwriters Labo ratories, 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 Depart ment of Government Relations and Science Policy, 1155 16th Street N.W., Wash ington, 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 me thod generate relatively small amounts of waste since only small amounts of reagents and solven ts are used. The matrices of concern are finished drinking water or source water. Howeve r, the Agency requires that laboratory waste management practices be conducted consistent wi th 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 addi tion, compliance is required with any sewage discharge permits and regulations, particularly the hazardous waste identification rules and land disposal restrictions. For further inform ation on waste management, see the publications
of the American Chemical Soci ety’s Laboratory Envir onment, Health & Safety Task Force on
the Internet at http://membership.acs.or g/c/ccs/publications.htm . Additional waste management information can be found in “Laboratory Waste Minimization and Pollution Prevention,” Copyright © 1996 Batt elle 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 Pr ocedures for Determinat ion 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: 7 th 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, FLOWCHART S, 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 accep table 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 CONDITION S USED FOR METHOD PERFORMANCE
RESULTS

Parameter Conditions a 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 o C Dry purge 100 mL/min for 2 min Desorb preheat temperature 250 o C Desorb cycle 260 o C for 1.0 min Bake rinse cycles Sparging vessel and au tosampler sample path rinsed twice Bake cycle 280 o C 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/MA SS SPECTROMETRY (GC/MS) CONDITIONS
FOR METHOD PERFORMANCE RESULTS

Parameter Conditions a
Column Restek Rtx ® -VMS 30 meter, 0.25 mm i.d., 1.4 μm d f 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, RECO MMENDED QUANTITATION IONS, AND
SUGGESTED INTERNAL STANDARD REFERENCES FOR FULL SCAN MODE a

Analyte Peak no. Fig.’s 2a, 2b, 2c RT Q-Ion IS b 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- d 3 (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 1524.3-36 Analyte Peak no. Fig.’s 2a, 2b, 2c RT Q-Ion IS b 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- d 5 (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 3524.3-37 Analyte Peak no. Fig.’s 2a, 2b, 2c RT Q-Ion IS b 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- d 4 (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- d 4 (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, RE COMMENDED QUANTITATION IONS, CONFIRMATION IONS, AND SUGGESTED INTERNAL STANDARD REFERENCES FOR
SIM MODE

Analyte RT Q-Ion IS a Reference methyl-t-butyl ether- d 3 (surrogate #1) 4.09 76 1
1,4-difluorobenzene (IS #1) 7.47 114 1
1,2-dibromoethane 10.26 107 2

chlorobenzene- d 5 (IS #2) 10.73 117 2
4-bromofluorobenzene (surrogate #2) 11.77 95 3
1,4-dichlorobenzene- d 4 (IS #3) 12.63 152 3
1,2-dichlorobenzene- d 4 (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 MINI MUM 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 0.018524.3-39 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 0.020524.3-40 TABLE 7. PRECISION AND ACCURACY OF METHOD ANA LYTES 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 RSD a 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 4.2524.3-41 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 RSD a 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 ANA LYTES FORTIFIED AT 0.50, 1.0 AND 10 μg/L IN DRINKING WA TER FROM A GROUND WATER SOURCE a 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., μ g/L (n=3) Mean % Recovery b RSD c Mean % Recovery b RSD Mean % Recovery b 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 4.4524.3-43 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., μ g/L (n=3) Mean % Recovery b RSD c Mean % Recovery b RSD Mean % Recovery b 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 CaCO 3 ); 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 ANA LYTES FORTIFIED AT 0.50, 1.0 AND 10 μg/L IN DRINKING WATE R FROM A SURFACE WATER SOURCE a 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., μ g/L (n=3) Mean % Recovery b RSD c Mean % Recovery b RSD Mean % Recovery b 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 2.2524.3-45 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., μ g/L (n=3) Mean % Recovery b RSD c Mean % Recovery b RSD Mean % Recovery b 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 CaCO 3 ); 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 MI NIMUM 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 ANA LYTES FORTIFIED AT 0.010, 0.020 AND 0.10 μg/L IN REAGEN T 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 RSD a 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 ANA LYTES FORTIFIED AT 0.010, 0.020 AND 0.10 μg/L IN DRINKING WATE R FROM A GROUND WATER SOURCE a 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.,

μ g/L (n=3) Mean % Recovery RSD b 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 ANA LYTES FORTIFIED AT 0.010, 0.020 AND 0.10 μg/L IN DRINKING WATE R FROM A SURFACE WATER SOURCE a 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., μ g/L (n=3) Mean % Recovery RSD b 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 WATER a (n=3 SAMPLES)

Day 0 Day 7 Day 14

Analyte Mean % Recovery RSD b 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 0.92524.3-48 Day 0 Day 7 Day 14

Analyte Mean % Recovery RSD b 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 CaCO 3 ); 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 qu antitation 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 La boratory 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 th e 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 QUAL ITY 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 FortifiedSample 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.524.3-51Figure 1. Mass chromatograms of "gases." @ 40 μg/L.524.3-52Figure 2a. Reconstructed total ion chromatogram: 40-μg/L procedural calibration standard.See Table 4 for peak number to peakname cross reference.524.3-53Figure 2b. Reconstructed total ion chromatogram: 40-μg/L procedural calibration standard.See Table 4 for peak number to peakname cross reference.524.3-54Figure 2c. Reconstructed total ion chromatogram: 40-μg/L procedural calibration standard.See Table 4 for peak number to peakname cross reference.524.3-55Figure 3. Reconstructed total ion chromatogram: method analytes fortified into drinking water @ 20μg/L.