### 524.2-1 METHOD 524.2. MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY CAPILLARY CO LUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY

Revision 4.1

Edited by J.W. Munch (1995)

A. Alford-Stevens, J.W. Eichelberger, W.L. Budde - Method 524, Rev. 1.0 (1983)

R.W. Slater, Jr. - Revision 2.0 (1986)

J.W. Eichelberger, and W.L. Budde - Revision 3.0 (1989)

J.W. Eichelberger, J.W. Munch, and T.A. Bellar - Revision 4.0 (1992)

NATIONAL EXPOSURE RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268

### 524.2-2 METHOD 524.2

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

1. SCOPE AND APPLICATION

1.1 This is a general purpose method for the identification and simultaneous measurement of purgeable volatile organic compounds in surface water, ground water, and drinking water in any stage of treatment (1,2). The method is applicable to a wide range of organic compounds, including the four trih alomethane disinfection by-products, that have sufficiently high volatility and low water solubility to be removed from water samples with purge and trap procedures. The following compounds can be determined by this method.

Chemical Abstract Service Analyte Registry Number

Acetone* 67-64-1 Acrylonitrile* 107-13-1 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 2-Butanone* 78-93-3 n-Butylbenzene 104-51-8 sec-Butylbenzene 135-98-8 tert-Butylbenzene 98-06-6 Carbon disulfide* 75-15-0 Carbon tetrachloride 56-23-5 Chloroacetonitrile* 107-14-2 Chlorobenzene 108-90-7 1-Chlorobutane* 109-69-3 Chloroethane 75-00-3 Chloroform 67-66-3 Chloromethane 74-87-3 2-Chlorotoluene 95-49-8 4-Chlorotoluene 106-43-4 Dibromochloromethane 124-48-1 1,2-Dibromo-3-chloropropane 96-12-8 1,2-Dibromoethane 106-93-4 Dibromomethane 74-95-3 1,2-Dichlorobenzene 95-50-1 1,3-Dichlorobenzene 541-73-1 1,4-Dichlorobenzene 106-46-7 trans-1,4-Dichloro-2-butene* 110-57-6 Dichlorodifluoromethane 75-71-8

### 524.2-3 1,1-Dichloroethane 75-34-3 1,2-Dichloroethane 107-06-2 1,1-Dichloroethene 75-35-4 cis-1,2-Dichloroethene 156-59-2 trans-1,2-Dichloroethene 156-60-5 1,2-Dichloropropane 78-87-5 1,3-Dichloropropane 142-28-9 2,2-Dichloropropane 590-20-7 1,1-Dichloropropene 563-58-6 1,1-Dichloropropanone* 513-88-2 cis-1,3-Dichloropropene 10061-01-5 trans-1,3-Dichloropropene 10061-02-6 Diethyl ether* 60-29-7 Ethylbenzene 100-41-4 Ethyl methacrylate* 97-63-2 Hexachlorobutadiene 87-68-3 Hexachloroethane* 67-72-1 2-Hexanone* 591-78-6 Isopropylbenzene 98-82-8 4-Isopropyltoluene 99-87-6 Methacrylonitrile* 126-98-7 Methylacrylate* 96-33-3 Methylene chloride 75-09-2 Methyl iodide* 74-88-4 Methylmethacrylate* 80-62-6 4-Methyl-2-pentanone* 108-10-1 Methyl-t-butyl ether* 1634-04-4 Naphthalene 91-20-3 Nitrobenzene* 98-95-3 2-Nitropropane* 79-46-9 Pentachloroethane* 76-01-7 Propionitrile* 107-12-0 n-Propylbenzene 103-65-1 Styrene 100-42-5 1,1,1,2-Tetrachloroethane 630-20-6 1,1,2,2-Tetrachloroethane 79-34-5 Tetrachloroethene 127-18-4 Tetrahydrofuran* 109-99-9 Toluene 108-88-3 1,2,3-Trichlorobenzene 87-61-6 1,2,4-Trichlorobenzene 120-82-1 1,1,1-Trichloroethane 71-55-6 1,1,2-Trichloroethane 79-00-5 Trichloroethene 79-01-6 Trichlorofluoromethane 75-69-4 1,2,3-Trichloropropane 96-18-4 1,2,4-Trimethylbenzene 95-63-6 1,3,5-Trimethylbenzene 108-67-8 Vinyl chloride 75-01-4 o-Xylene 95-47-6

### 524.2-4 m-Xylene 108-38-3 p-Xylene 106-42-3

* New Compound in Revision 4.0

1.2 Method detection limits (MDLs) (3) are compound, instrument and especially matrix dependent and vary from approximately 0.02 to 1.6 

### : g/L. The applicable concentration range of this method is prim arily column and matrix dependent, and is approximately 0.02 to 200 

### : g/L when a wide-bore thick-film capillary column is used. Narrow-bore thin-film columns may have a capacity which limits the range to about 0.02 to 20 

### : g/L. Volatile water soluble, polar compounds which have relatively low purging efficiencies can be determined us ing this method. Such compounds may be more susceptible to matrix effects, and the quality of the data may be adversely influenced.

1.3 Analytes that are not separated chromato graphically, but which have different mass spectra and noninterfering quantitation ions (Table 1), can be identified and measured in the same calibration mixture or water sa mple as long as their concentrations are somewhat similar (Sect. 11.6.2). Analytes that have very similar mass spectra cannot be individually identified and measured in the same calibration mixture or water sample unless they have different retention times (Sect. 11.6.3). Coeluting compounds with very similar mass spectra, typically many structural isomers, must be reported as an isomeric group or pair. Two of the thr ee isomeric xylenes and two of the three dichlorobenzenes are examples of structural isomers that may not be resolved on the capillary column, and if not, must be reported as isomeric pairs. The more water soluble compounds (> 2% solubility) and compounds with boiling points above 200°C are purged from the water matrix with lowe r efficiencies. These analytes may be more susceptible to matrix effects.

2. SUMMARY OF METHOD

2.1 Volatile organic compounds and surrogates with low water solubility are extracted (purged) from the sample matrix by bubbling an inert gas through the aqueous sample. Purged sample components are trapped in a tube containing suitable sorbent materials. When purging is complete, the sorbent tube is heated and backflushed with helium to desorb the trapped sample components into a capillary gas chromatography (GC) column interfaced to a mass spectrometer (MS). The column is temperature programmed to facilitate the separation of the method analytes which are then detected with the MS. Compounds eluting from the GC column are identified by comparing their measured mass spectra and retention times to reference spectra and retention times in a data base. Reference spectra and retention times for analytes are obtained by the measurement of calibration standards under the same conditions used for samples. Analytes are quantitated usin g procedural standard calibration (Sect. 3.14). The concentration of each identified component is measured by relating the MS response of the quantitation ion produced by that compound to the MS response of the quantitation ion produced by a compound that is used as an internal standard. Surrogate analytes, whose concentrations are known in every sample, are measured with the same internal standard calibration procedure.

### 524.2-5 3. DEFINITIONS

3.1 INTERNAL STANDARD (IS) -- A pure analyte(s) added to a sample, extract, or standard solution in known amount(s) and used to measure the relative responses of other method analytes and surrogates that are components of the same sample or solution. The internal standard must be an analyte that is not a sample component.

3.2 SURROGATE ANALYTE (SA) -- A pure analyte(s), which is extremely unlikely to be found in any sample, and which is added to a sample aliquot in known amount(s) before extraction or other processing and is measured with the same procedures used to measure other sample components. The purpose of the SA is to monitor method performance with each sample.

3.3 LABORATORY DUPLICATES (LD1 and LD2) -- Two aliquots of the same sample taken in the laboratory and analyzed separately wi th identical procedures. Analyses of LD1 and LD2 indicates precision associated with laboratory procedures, but not with sample collection, preservation, or storage procedures.

3.4 FIELD DUPLICATES (FD1 and FD2) -- Two separate samples collected at the same time and place under identical circumstances and treated exactly the same throughout field and laboratory procedures. Analyses of FD1 and FD2 give a measure of the precision associated with sample collection, preservation and storage, as well as with laboratory procedures.

3.5 LABORATORY REAGENT BLANK (LRB) -- An aliquot of reagent water or other blank matrix that is treated exactly as a samp le including exposure to all glassware, equipment, solvents, reagents, internal standards, and surrogates that are used with other samples. The LRB is used to determine if method analytes or other interferences are present in the laboratory environment, the reagents, or the apparatus.

3.6 FIELD REAGENT BLANK (FRB) -- An aliquot of reagent water or other blank matrix that is placed in a sample container in th e laboratory and treated as a sample in all respects, including shipment to the sampling site, exposure to sampling site conditions, storage, preservation, and all analytical pr ocedures. The purpose of the FRB is to determine if method analytes or other interferences are present in the field environment.

3.7 LABORATORY PERFORMANCE CHECK SOLUTION (LPC) -- A solution of one or more compounds (analytes, surrogates, internal standard, or other test compounds) used to evaluate the performance of the instrument system with respect to a defined set of method criteria.

3.8 LABORATORY FORTIFIED BLANK (LFB) -- An aliquot of reagent water or other blank matrix to which known quantities of the m ethod analytes are added in the laboratory. The LFB is analyzed exactly like a sample, an d its purpose is to determine whether the methodology is in control, and whether th e laboratory is capable of making accurate and precise measurements.

3.9 LABORATORY FORTIFIED SAMPLE MATRIX (LFM) -- An aliquot of an environmental sample to which known quantities of the m ethod analytes are added in the laboratory.

### 524.2-6 The LFM is analyzed exactly like a sample, an d its purpose is to determine whether the sample matrix contributes bias to the analytical results. The background concentrations of the analytes in the sample matrix must be determined in a separate aliquot and the measured values in the LF M corrected for background concentrations.

3.10 STOCK STANDARD SOLUTION (SSS) -- A concentrated solution containing one or more method analytes prepared in the labo ratory using assayed reference materials or purchased from a reputable commercial source.

3.11 PRIMARY DILUTION STANDARD SOLUTION (PDS) -- A solution of several analytes prepared in the laboratory from stock stan dard solutions and diluted as needed to prepare calibration solutions and other needed analyte solutions.

3.12 CALIBRATION STANDARD (CAL) -- A solution prepared from the primary dilution standard solution or stock standard solutions and the internal standards and surrogate analytes. The CAL solutions are used to calibrate the instrument response with respect to analyte concentration.

3.13 QUALITY CONTROL SAMPLE (QCS) -- A solution of method analytes of known concentrations which is used to fortify an aliquot of LRB or sample matrix. The QCS is obtained from a source external to the laboratory and different from the source of calibration standards. It is used to check laboratory performance with externally prepared test materials.

3.14 PROCEDURAL STANDARD CALIBRATION -- A calibration method where aqueous calibration standards are prepared and processed (e.g. purged,extracted, and/or derivatized) in exactly the same manner as a sample. All steps in the process from addition of sampling preservatives through instrumental analyses are included in the calibration. Using procedural standard calib ration compensates for any inefficiencies in the processing procedure.

4. INTERFERENCES

4.1 During analysis, major contaminant sources are volatile materials in the laboratory and impurities in the inert purging gas and in the sorbent trap. The use of Teflon tubing, Teflon thread sealants, or flow controllers with rubber components in the purging device should be avoided since such mater ials out-gas organic compounds which will be concentrated in the trap during the purge operation. Analyses of laboratory reagent blanks provide information about the pres ence of contaminants. When potential interfering peaks are noted in laboratory re agent blanks, the analyst should change the purge gas source and regenerate the molecular sieve purge gas filter. Subtracting blank values from sample results is not permitted.

4.2 Interfering contamination may occur when a sample containing low concentrations of volatile organic compounds is analyz ed immediately after a sample containing relatively high concentrations of volatile organic compounds. A preventive technique is between-sample rinsing of the purging a pparatus and sample syringes with two portions of reagent water. After analysis of a sample containing high concentrations of volatile organic compounds, one or more laboratory reagent blanks should be analyzed to check for cross-contamination.

### 524.2-7 4.3 Special precautions must be taken to determine methylene chloride. The analytical and sample storage area should be isolated from all atmospheric sources of methylene chloride, otherwise random background levels will result. Since methylene chloride will permeate Teflon tubing, all GC carrier gas lines and purge gas plumbing should be constructed of stainless steel or copper tubi ng. Laboratory worker's clothing should be cleaned frequently since clothing previously exposed to methylene chloride fumesduring common liquid/liquid extraction procedures can contribute to sample contamination.

4.4 Traces of ketones, methylene chloride, and some other organic solvents can be present even in the highest purity methanol. This is another potential source of contamination, and should be assessed before standards are prepared in the methanol.

5. SAFETY

5.1 The toxicity or carcinogenicity of chemical s 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 awareness of OSHA regulations regarding safe handling of chemicals used in this method. Additional references to labora tory safety are available (4-6) for the information of the analyst.

5.2 The following method analytes have been tentatively classified as known or suspected human or mammalian carcinogens: benzene, carbon tetrachloride, 1,4-dichlorobenzene, 1,2-dichlorethane, hexachlorobutadiene, 1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, chloroform, 1,2-dibromoethane,tetrachloroethene, tric hloroethene, and vinyl chloride. Pure standard materials and stock standard solutions of these compounds should be handled in a hood. A NIOSH/MESA approved toxic gas respirator should be worn when the analyst handles high concentrations of these toxic compounds.

6. EQUIPMENT AND SUPPLIES (All specifications are suggested. Catalog numbers are included for illustration only.)

6.1 SAMPLE CONTAINERS -- 40-mL to 120-mL screw cap vials each equipped with a Teflon faced silicone septum. Prior to use, wash vials and septa with detergent and rinse with tap and distilled water. Allow the vials and septa to air dry at room temperature, place in a 105 o C oven for 1 hr, then remove and allow to cool in an area known to be free of organics.

6.2 PURGE AND TRAP SYSTEM -- The purge and tr ap system consists of three separate pieces of equipment: purging device, trap, and desorber. Systems are commercially available from several sources that m eet all of the following specifications.

6.2.1 The all glass purging device (Figure 1) should be designed to accept 25-mL samples with a water column at least 5 cm deep. A smaller (5-mL) purging device is recommended if the GC/MS system has adequate sensitivity to obtain the method detection limits re quired. Gaseous volumes above the sample must be kept to a minimum (< 15 mL) to eliminate dead volume effects. A glass frit should be installed at the base of the sample chamber so

### 524.2-8 the purge gas passes through the water column as finely divided bubbles with a diameter of < 3 mm at the origin. Needle spargers may be used, however, the purge gas must be introduced at a point about 5 mm from the base of the water column. The use of a moisture control device is recommended to prohibit much of the trapped water vapor from entering the GC/MS and eventually causing instrumental problems.

6.2.2 The trap (Figure 2) must be at least 25 cm long and have an inside diameter of at least 0.105 in. Starting from the inlet, the trap should contain 1.0 cm of methyl silicone coated packing and the following amounts of adsorbents: 1/3 of 2,6-diphenylene oxide polymer, 1/3 of silica gel, and 1/3 of coconut charcoal. If it is not necessary to determine dichlorodifluoromethane, the charcoal can be eliminated and the poly mer increased to fill 2/3 of the trap. Before initial use, the trap should be conditioned overnight at 180 o C by backflushing with an inert gas flow of at least 20 mL/min. Vent the trap effluent to the room, not to the analytical column. Prior to daily use, the trap should be conditioned for 10 min at 180 o C with backflushing. The trap may be vented to the analytical column during daily conditioning; however, the column must be run through the temperature program prior to analysis of samples. The use of alternative sorb ents is acceptable provided the data acquired meets all quality control criteria described in Section 9, and provided the purge and desorption procedures specified in Section 11 of the method are not changed . Specifically, the purging time, the purge gas flow rate, and the desorption time may not be changed. Since many of the potential alternate sorbents may be thermally st able above 180°C, alternate traps may be desorbed and baked out at higher temperatures than those described in Section 11. If higher temperatures are used, the analyst should monitor the data for possible analyte and/or trap decomposition.

6.2.3 The use of the methyl silicone coated packing is recommended, but not mandatory. The packing serves a dual purpose of protecting the Tenax adsorbant from aerosols, and also of insuring that the Tenax is fully enclosed within the heated zone of the trap thus eliminating potential cold spots. Alternatively, silanized glass wool may be used as a spacer at the trap inlet.

6.2.4 The desorber (Figure 2) must be capable of rapidly heating the trap to 180 o C either prior to or at the beginning of the flow of desorption gas. The polymer section of the trap should not be heated higher than 200 o C or the life expectancy of the trap will decrease. Trap failure is characterized by a pressure drop in excess of 3 lb/in 2 across the trap during purging or by poor bromoform sensitivities. The desorber design illustrated in Fig. 2 meets these criteria.

6.3 GAS CHROMATOGRAPHY/MASS SPECTR OMETER/DATA SYSTEM (GC/MS/DS)

6.3.1 The GC must be capable of temperature programming and should be equipped with variable-constant differential flow controllers so that the column flow rate will remain constant throughout desorption and temperature program operation. If the column oven is to be cooled to 10 o C or lower, a subambient oven controller will likely be required. If syringe injections of 4-

### 524.2-9 bromofluorobenzene (BFB) will be used, a split/splitless injection port is required.

6.3.2 Capillary GC Columns. Any gas chromatography column that meets the performance specifications of this m ethod may be used (Sect. 10.2.4.1). Separations of the calibration mixture mu st be equivalent or better than those described in this method. Four useful columns have been evaluated, and observed compound retention times for these columns are listed in Table 2.

6.3.2.1 Column 1 -- 60 m x 0.75 mm ID VOCOL (Supelco, Inc.) glass wide-bore capillary with a 1.5 

### : m film thickness.

Column 2 -- 30 m x 0.53 mm ID DB-624 (J&W Scien-tific, Inc.) fused silica capillary with a 3 

### : m film thickness.

Column 3 -- 30 m x 0.32 mm ID DB-5 (J&W Scientific, Inc.) fused silica capillary with a 1 

### : m film thickness.

Column 4 -- 75 m x 0.53 mm id DB-624 (J&W Scien-tific, Inc.) fused silica capillary with a 3 

### : m film thickness.

6.3.3 Interfaces between the GC and MS. The interface used depends on the column selected and the gas flow rate.

6.3.3.1 The wide-bore columns 1, 2, and 4 have the capacity to accept the standard gas flows from the trap during thermal desorption, and chromatography can begin with the onset of thermal desorption. Depending on the pumping capacity of the MS, an additional interface between the end of the column and the MS may be required. An open split interface (7) or an all-glass jet separator is an acceptable interface. Any interface can be used if the performance specifications desc ribed in this method (Sect. 9 and 10) can be achieved. The end of the transfer line after the interface, or the end of the analytical column if no interface is used, should be placed within a few mm of the MS ion source.

6.3.3.2 When narrow bore column 3 is used, a cryogenic interface placedjust in front of the column inlet is suggested. This interface condenses the desorbed sample components in a narrow band on an uncoated fused silica precolumn using liquid nitrogen cooling. When all analytes have been desorbed from the trap, the interface is rapidly heated to transfer them to the analytical column. The end of the analytical column should be placed within a few mm of the MS ion source. A potential problem with this interface is blockage of the interface by frozen water from the trap. Thiscondition will result in a major loss in sensitivity and chromatographic resolution.

6.3.4 The mass spectrometer must be capabl e of electron ionization at a nominal electron energy of 70 eV. The spectrometer must be capable of scanning from

### 524.2-10 35 to 260 amu with a complete scan cycle time (including scan overhead) of 2 sec or less. (Scan cycle time = Total MS data acquisition time in seconds divided by number of scans in the chromatogram.) The spectrometer must produce a mass spectrum that meets all cr iteria in Table 3 when 25 ng or lessof 4-bromofluorobenzene (BFB) is introduced into the GC. An average spectrum across the BFB GC peak may be used to test instrument performance.

6.3.5 An interfaced data system is required to acquire, store, reduce, and output mass spectral data. The computer so ftware should have the capability of processing stored GC/MS data by recognizing a GC peak within any given retention time window, comparing the mass spectra from the GC peak with spectral data in a user-created data base, and generating a list of tentatively identified compounds with their retention times and scan numbers. The software must allow integration of the ion abundance of any specific ion between specified time or scan number limits. The software should also allow calculation of response factors as defined in Sect. 10.2.6 (or construction of a linear or second order regression calibration curve), calculation of responsefactor statistics (mean and standard deviation), and calculation of concentrations of analytes using either the calibration curve or the equation in Sect. 12.

6.4 SYRINGE AND SYRINGE VALVES

6.4.1 Two 5-mL or 25-mL glass hypodermic syringes with Luer-Lok tip (depending on sample volume used).

6.4.2 Three 2-way syringe valves with Luer ends.

6.4.3 Micro syringes - 10, 100 

### : L.

6.4.4 Syringes - 0.5, 1.0, and 5-mL, gas tight with shut-off valve.

6.5 MISCELLANEOUS

6.5.1 Standard solution storage containers -- 15-mL bottles with Teflon lined screw
caps.

7. REAGENTS AND STANDARDS

7.1 TRAP PACKING MATERIALS

7.1.1 2,6-Diphenylene oxide polymer, 60/80 mesh, chromatographic grade (Tenax GC or equivalent).

7.1.2 Methyl silicone packing (optional) -- OV-1 (3%) on Chromosorb W, 60/80 mesh, or equivalent.

7.1.3 Silica gel -- 35/60 mesh, Davison, grade 15 or equivalent.

7.1.4 Coconut charcoal -- Prepare from Barnebey Cheney, CA-580-26 lot #M-2649 (or equivalent) by crushing through 26 mesh screen.

### 524.2-11 7.2 REAGENTS

7.2.1 Methanol -- Demonstrated to be free of analytes.

7.2.2 Reagent water -- Prepare reagent water by passing tap water through a filter bed containing about 0.5 kg of activated carbon, by using a water purification system, or by boiling distilled water for 15 min followed by a 1-h purge with inert gas while the water temperature is held at 90 o C. Store in clean, narrow-mouth bottles with Teflon lined septa and screw caps.

7.2.3 Hydrochloric acid (1+1) -- Carefully add measured volume of conc. HCl to equal volume of reagent water.

7.2.4 Vinyl chloride -- Certified mixtures of vinyl chloride in nitrogen and pure vinyl chloride are available from several sour ces (for example, Matheson, Ideal Gas Products, and Scott Gases).

7.2.5 Ascorbic acid -- ACS reagent grade, granular.

7.2.6 Sodium thiosulfate -- ACS reagent grade, granular.

7.3 STOCK STANDARD SOLUTIONS -- These solutions may be purchased as certified solutions or prepared from pure standard materials using the following procedures. One of these solutions is required for every analyte of concern, every surrogate, and the internal standard. A useful working concentration is about 1-5 mg/mL.

7.3.1 Place about 9.8 mL of methanol into a 10-mL ground-glass stoppered volumetric flask. Allow the flask to stand, unstoppered, for about 10 min or until all alcohol-wetted surfaces have dried and weigh to the nearest 0.1 mg.

7.3.2 If the analyte is a liquid at room temperature, use a 100- 

### : L syringe and immediately add two or more drops of reference standard to the flask. Be sure that the reference standard falls di rectly into the alcohol without contacting the neck of the flask. If the anal yte is a gas at room temperature, fill a 5-mL valved gas-tight syringe with th e standard to the 5.0-mL mark, lower the needle to 5 mm above the methanol meniscus, and slowly inject the standard into the neck area of the flas k. The gas will rapidly dissolve in the methanol.

7.3.3 Reweigh, dilute to volume, stopper, then mix by inverting the flask several times. Calculate the concentration in 

### : g/ 

### : L from the net gain in weight. When compound purity is certified at 96% or greater, the weight can be used without correction to calculate the concentration of the stock standard.

7.3.4 Store stock standard solutions in 15-mL bottles equipped with Teflon lined screw caps. Methanol solutions of acrylonitrile, methyl iodide, and methyl acrylate are stable for only one week at 4°C. Methanol solutions prepared from other liquid analytes are stable for at least 4 weeks when stored at 4 o C.

### 524.2-12 Methanol solutions prepared from gaseous analytes are not stable for more than 1 week when stored at < 0 o C; at room temperature, they must be discarded after 1 day.

7.4 PRIMARY DILUTION STANDARDS -- Use stock standard solutions to prepare primary dilution standard solutions that contain all the analytes of concern in methanol or other suitable solvent. The primary dilution standards should be prepared at concentrations that can be easily diluted to prepare aqueou s calibration solutions that will bracket the working concentration range. Store the primary dilution standard solutions with minimal headspace and check frequently for signs of deterioration or evaporation, especially just before preparing calibration solutions. Storage times described for stock standard solutions in Sect. 7.3.4 also apply to primary dilution standard solutions.

7.5 FORTIFICATION SOLUTIONS FOR INTERNAL STANDARD AND SURROGATES

7.5.1 A solution containing the internal standard and the surrogate compounds is required to prepare laboratory reagen t blanks (also used as a laboratoryperformance check solution), and to fortify each sample. Prepare a fortification solution containing fluorobenzene (internal standard), 1,2- dichlorobenzene-d 4 (surrogate), and BFB (surrogate) in methanol at concentrations of 5 

### : g/mL of each (any appropriate concentration is acceptable). A 5- 

### : Laliquot of this solution added to a 25-mL water sample volume gives concentrations of 1 

### : g/L of each. A 5- 

### : L aliquot of this solution added to a 5-mL water sample volume gives a concentration of 5 

### : g/L of each. Additional internal standards and surrogate analytes are optional. Additional surrogate compounds should be similar in physical and chemical characteristics to the analytes of concern.

7.6 PREPARATION OF LABORATORY REAGENT BLANK (LRB) -- Fill a 25-mL (or 5-mL)syringe with reagent water and adjust to the mark (no air bubbles). Inject an appropriate volume of the fortification solution containing the internal standard and surrogates through the Luer Lok valve into the reagent water. Transfer the LRB to the purging device. See Sect. 11.1.2.

7.7 PREPARATION OF LABORATORY FORTIFIE D BLANK -- Prepare this exactly like a calibration standard (Sect. 7.8). This is a calibration standard that is treated as a sample.

7.8 PREPARATION OF CALIBRATION STANDARDS

7.8.1 The number of calibration solutions (CALs) needed depends on the calibration range desired. A minimum of three CAL solutions is required to calibrate a range of a factor of 20 in concentration. For a factor of 50, use at least four standards, and for a factor of 100 at least five standards. One calibration standard should contain each analyte of concern at a concentration of 2-10 times the method detection limit (Tables 4, 5, and 7) for that compound. The other CAL standards should contain each analyte of concern at concentrations that define the range of the method. Every CAL solution contains the internal

### 524.2-13 standard and the surrogate compounds at the same concentration (5 

### : g/L suggested for a 5-mL sample; 1 

### : g/L for a 25-mL sample).

7.8.2 To prepare a calibration standard, add an appropriate volume of a primary dilution standard containing all analytes of concern to an aliquot of acidified (pH 2) reagent water in a volumetric flask. Also add an appropriate volume of internal standard and surrogate compound solution from Sect. 7.5.1. Use a microsyringe and rapidly inject the meth anol solutions into the expanded area of the filled volumetric flask. Remove the needle as quickly as possible after injection. Mix by inverting the flask three times only. Discard the contents contained in the neck of the flask. Aqueous standards are not stable in a volumetric flask and should be discarded after 1 hr unless transferred to a sample bottle and sealed immediatel y. Alternately, aqueous calibration standards may be prepared in a gas tight, 5 mL or 25 mL syringe. NOTE: If unacidified samples are being analyzed for THMs only, calibration standards should be prepared without acid.

8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1 SAMPLE COLLECTION AND DECHLORINATION

8.1.1 Collect all samples in duplicate. If samples, such as finished drinking water, are suspected to contain residual chlorine, add about 25 mg of ascorbic acid per 40 mL of sample to the sample bottle before filling. If analytes that are gases at room temperature (such as vinyl chloride), or analytes in Table 7 are not to be determined, sodium thiosulfate is recommended to reduce the residual chlorine. Three milligrams of sodium thiosulfate should be added for each 40 mL of water sample. NOTE: If the residual chlorine is likely to be present > 5 mg/L, a determination of the amount of the chlorine may be necessary. Diethyl-pphenylenediamine (DPD) test kits ar e commercially available to determine residual chlorine in the field. Add an additional 25 mg of ascorbic acid or 3 mg of sodium thiosulfate per each 5 mg/L of residual chlorine.

8.1.2 When sampling from a water tap, open the tap and allow the system to flush until the water temperature has stabilized (usually about 10 min). Adjust the flow to about 500 mL/min and collect duplicate samples containing the desired dechlorinating agent from the flowing stream.

8.1.3 When sampling from an open body of water, partially fill a 1-quart wide-mouth bottle or 1-L beaker with sample from a representative area. Fill duplicate sample bottles containing the desired dechlorinating agent with sample from the larger container.

8.1.4 Fill sample bottles to overflowing, but take care not to flush out the rapidly dissolving dechlorinating agent. No air bubbles should pass through the sample as the bottle is filled, or be trapped in the sample when the bottle is sealed.

### 524.2-14 8.2 SAMPLE PRESERVATION

8.2.1 Adjust the pH of all samples to < 2 at the time of collection , but after dechlorination, by carefully adding tw o drops of 1:1 HCl for each 40 mL of sample. Seal the sample bottles, Teflon face down, and mix for 1 min. Exceptions to the acidification requirem ent are detailed in Sections 8.2.2 and 8.2.3. NOTE: Do not mix the ascorbic acid or sodium thiosulfate with the HCl in the sample bottle prior to sampling.

8.2.2 When sampling for THM analysis only , acidification may be omitted if sodium thiosulfate is used to dechlorinate the sa mple. This exception to acidification does not apply if ascorbic acid is used for dechlorination.

8.2.3 If a sample foams vigorously when HCl is added, discard that sample. Collect a set of duplicate samples but do not acidify them. These samples must be flagged as "not acidified" and must be stored at 4°C or below. These samples must be analyzed within 24 hr of collection time if they are to be analyzed for any compounds other than THMs.

8.2.4 The samples must be chilled to about 4 o C when collected and maintained at that temperature until analysis. Field sa mples that will not be received at the laboratory on the day of collection must be packaged for shipment with sufficient ice to ensure that they will arri ve at the laboratory with a substantial amount of ice remaining in the cooler.

8.2 SAMPLE STORAGE

8.2.1 Store samples at 

### # 4 o C until analysis. The sample storage area must be free of organic solvent vapors and direct or intense light.

8.2.2 Analyze all samples within 14 days of collection. Samples not analyzed within this period must be discarded and replaced.

8.3 FIELD REAGENT BLANKS (FRB)

8.3.1 Duplicate FRBs must be handled along with each sample set, which is composed of the samples collected from the same general sample site at approximately the same time. At the lab oratory, fill field blank sample bottles with reagent water and sample preservatives, seal, and ship to the sampling site along with empty sample bottles and back to the laboratory with filledsample bottles. Wherever a set of samples is shipped and stored, it is accompanied by appropriate blanks. FRBs must remain hermetically sealed until analysis.

8.3.2 Use the same procedures used for samples to add ascorbic acid and HCl to blanks (Sect. 8.1.1). The same batc h of ascorbic acid and HCl should be used for the field reagent blanks as for the field samples.

### 524.2-15 9. QUALITY CONTROL

9.1 Quality control (QC) requirements are the initial demonstration of laboratory capability followed by regular analyses of laboratory reagent blanks, field reagent blanks, and laboratory fortified blanks. A MDL for each analyte must also be determined. Each laboratory must maintain records to document the quality of the data generated. Additional quality control practices are recommended.

9.2 Initial demonstration of low system background. Before any samples are analyzed, it must be demonstrated that a laboratory reagent blank (LRB) is reasonably free of contamination that would prevent the determination of any analyte of concern. Sources of background contamination are glassware, purge gas, sorbents, reagent water, and equipment. Background contamination must be reduced to an acceptable level before proceeding with the next section. In gener al, background from method analytes should be below the method detection limit.

9.3 Initial demonstration of laboratory accuracy and precision. Analyze four to seven replicates of a laboratory fortified blank containing each analyte of concern at a concentration in the range of 2-5 

### : g/L depending upon the calibration range of the instrumentation.

9.3.1 Prepare each replicate by adding an appropriate aliquot of a quality control sample to reagent water. It is recommended that a QCS from a source different than the calibration standards be used for this set of LFBs, since it will serve as a check to verify the accu racy of the standards used to generate the calibration curve. This is particular ly useful if the laboratory is using the method for the first time, and has no historical data base for standards. Prepare each replicate by adding an appropriate aliquot of a quality control sample to reagent water. Also add the appropriate amounts of internal standard and surrogates. If it is expected that field samples will contain a dechlorinating agent and HCl, then add these to the LFBs in the same amounts proscribed in Sect. 8.1.1. If only THMs are to be determined and field samples do not contain HCl, then do not acidify LFBs. Analyze each replicate according to the procedures described in Section 11.

9.3.2 Calculate the measured concentration of each analyte in each replicate, the mean concentration of each analyte in all replicates, and mean accuracy (as mean percentage of true value) for each analyte, and the precision (as relative standard deviation, RSD) of the measurements for each analyte.

9.3.3 Some analytes, particularly early eluting gases and late eluting higher molecular weight compounds, will be measured with less accuracy and precision than other analytes. However, the accuracy and precision for all analytes must fall within the limits expressed below. If these criteria are not met for an analyte of interest, take remedial acti on and repeat the measurements for that analyte until satisfactory performance is achieved. For each analyte, the mean accuracy must be 80-120% (i.e. an accuracy of ± 20%). The preci-

### 524.2-16 sion of the recovery (accuracy) for each analyte must be less than twenty percent (<20%). These criteria are different than the ± 30% response factorcriteria specified in Sect. 10.3.5. The criteria differ, because the measurements in Sect. 9.3.3 as part of the initial demonstration of capability are meant to be more stringent than the continuing calibration measurements in Sect. 10.3.5.

9.3.4 To determine the MDL, analyze a minimum of 7 LFBs prepared at a low concentration. MDLs in Table 5 were calculated from samples fortified from 0.1-0.5 

### : g/L, which can be used as a guide, or use calibration data to estimate a concentration for each analy te that will yield a peak with a 3-5 signal to noise response. Analyze the 7 replicates as described in Sect.11, and on a schedule that results in the analyses being conducted over several days. Calculate the mean accuracy and standard deviation for each analyte. Calculate the MDL using the equation in Sect. 13.

9.3.5 Develop and maintain a system of co ntrol charts to plot the precision and accuracy of analyte and surrogate measurements as a function of time. Charting surrogate recoveries is an es pecially valuable activity because surrogates are present in every sample and the analytical results will form a significant record of data quality.

9.4 Monitor the integrated areas of the quantitation ions of the internal standards and surrogates (Table 1) in all samples, conti nuing calibration checks, and blanks. These should remain reasonably constant over time. An abrupt change may indicate a matrix effect or an instrument problem. If a cryogenic interface is utilized, it may indicate an inefficient transfer from the trap to the column. These samples must be reanalyzed or a laboratory fortified duplicate sample analyzed to test for matrix effect. A more gradual drift of more than 50% in any area is indicative of a loss in sensitivity, and the problem must be found and corrected.

9.5 LABORATORY REAGENT BLANKS (LRB) -- With each batch of samples processed as agroup within a work shift, analyze a LRB to determine the background system contamination.

9.6 Assessing Laboratory Performance. Use the procedures and criteria in Sects. 10.3.4 and 10.3.5 to evaluate the accuracy of the measurement of the laboratory fortified blank (LFB), which must be analyzed with each batch of samples that is processed as a group within a work shift. If more than 20 samples are in a work shift batch, analyze one LFB per 20 samples. Prepare the LFB wi th the concentration of each analyte that was used in the Sect. 9.3.3 analysis. If th e acceptable accuracy for this measurement (±30%) is not achieved, the problem must be solved before additional samples may be reliably analyzed. Acceptance criteria for the IS and surrogate given in Sect.10.3.4 also applies to this LFB.

Since the calibration check sample in Sect. 10.3.5 and the LFB are made the same way and since procedural standards are us ed, the sample analyzed here may also be

### 524.2-17 used as a calibration check in Sect. 10.3.5. Add the results of the LFB analysis to the control charts to document data quality.

9.7 If a water sample is contaminated with an analyte, verify that it is not a sampling error by analyzing a field reagent blank. The results of these analyses will help define contamination resulting from field sampling, storage and transportation activities. If the field reagent blank shows unacceptable contamination, the analyst should identify and eliminate the contamination.

9.8 At least quarterly, replicate LFB data should be evaluated to determine the precision of the laboratory measurements. Add these re sults to the ongoing control charts to document data quality.

9.9 At least quarterly, analyze a quality control sample (QCS) from an external source. If measured analyte concentrations are not of acceptable accuracy, check the entire analytical procedure to locate and correct the problem source.

9.10 Sample matrix effects have not been observ ed when this method is used with distilled water, reagent water, drinking water, or gr ound water. Therefore, analysis of a laboratory fortified sample matrix (LFM) is not required unless the criteria in Section9.4 are not met. If matrix effects are observed or suspected to be causing low recoveries, analyze a laboratory fortified matrix sa mple for that matrix. The sample results should be flagged and the LFM results should be reported with them.

9.11 Numerous other quality control measures are incorporated into other parts of this procedure, and serve to alert the analyst to potential problems.

10. CALIBRATION AND STANDARDIZATION

10.1 Demonstration and documentation of accept able initial calibration is required before any samples are analyzed. In addition, acceptable performance must be confirmed intermittently throughout analysis of sample s by performing continuing calibration checks. These checks are required at the beginning of each work shift, but no less than every 12 hours. Additional periodic calibration checks are good laboratory practice. It is highly recommended that an additional calibration check be performed at the end of any cycle of continuous instrument operation, so that each set of field samples is bracketed by calibration check standards. NOTE: Since this method uses procedural standards, the analysis of the labo ratory fortified blank, which is required in Sect. 9.6, may be used here as a calibration check sample.

10.2 INITIAL CALIBRATION

10.2.1 Calibrate the mass and abundance sc ales of the MS with calibration compounds and procedures prescribed by th e manufacturer with any modifications necessary to meet the requirements in Sect. 10.2.2.

### 524.2-18 10.2.2 Introduce into the GC (either by purging a laboratory reagent blank or making a syringe injection) 25 ng or less of BFB and acquire mass spectra for m/z 35-260 at 70 eV (nominal). Use the purging procedure and/or GC conditions given in Sect. 11. If the spectrum does not meet all criteria in Table 3, the MS must be returned and adjusted to meet all criteria before proceeding with calibration. An average spectrum across the GC peak may be used to evaluate the performance of the system.

10.2.3 Purge a medium CAL solution, (e.g., 10-20 

### : g/L) using the procedure given in Sect. 11.

10.2.4 Performance criteria for calibration standards. Examine the stored GC/MS data with the data system software. Figures 3 and 4 shown acceptable total ion chromatograms.

10.2.4.1 GC performance. Good column performance will produce symmetrical peaks with minimum tailing for most compounds. If peaks are unusually broad, or if there is poor resolution between peaks, the wrong column has been selected or remedial action is probably necessary (Sect.10.3.6).

10.2.4.2 MS sensitivity. The GC/MS/DS peak identification software should be able to recognize a GC peak in the appropriate retention time window for each of the compounds in calibration solution, and make correct tentative identifications. If fewer than 99% of the compounds are recognized, system maintenance is required. See Sect. 10.3.6.

10.2.5 If all performance criteria are met, purge an aliquot of each of the other CAL solutions using the same GC/MS conditions.

10.2.6 Calculate a response factor (RF) for each analyte and isomer pair for each CALsolution using the internal standard fluorobenzene. Table 1 contains suggested quantitation ions for all compounds. This calculation is supported in acceptable GC/MS data system software (Sect. 6.3.5), and many other software programs. RF is a unitless number, but units used to express quantities of analyte and internal standard must be equivalent.

(A
x )(Q is ) RF = (A is )(Q
x )

where: A
x = integrated abundance of the quantitation ion of the analyte. A is = integrated abundance of the quantitation ion of the internal standard.

### 524.2-19 Q
x = quantity of analyte purged in nanograms or concentration units. Q is = quantity of internal standard purged in ng or concentration units.

10.2.6.1 For each analyte and surrogate, calculate the mean RF from analyses of CAL solutions. Calculate the standard deviation (SD) and the relative standard deviation (RSD) from each mean: RSD = 100 (SD/M). If the RSD of any analyte or surrogate mean RF exceeds 20%, either analyze additional aliquots of appropriate CAL solutions to obtain an acceptable RSD of RFs over the entire concentration range, or take action to improve GC/MS performance Sect. 10.3.6). Surrogate compounds are present at the same concentration on every sample, calibration standard, and all types of blanks.

10.2.7 As an alternative to calculating mean response factors and applying the RSD test, use the GC/MS data system software or other available software to generate a linear or second order regression calibration curve, by plotting A/A is vs. Q
x .
10.3 CONTINUING CALIBRATION CHECK -- Verify th e MS tune and initial calibration at the beginning of each 12-hr work shift during which analyses are performed using the following procedure. Additional periodic calib ration checks are good laboratory practice. It is highly recommended that an additional calibration check be performed at the end of any cycle of continuous instrument operation, so that each set of field samples is bracketed by calibration check standards.

10.3.1 Introduce into the GC (either by purging a laboratory reagent blank or making a syringe injection) 25 ng or less of BFB and acquire a mass spectrum that includes data for m/z 35-260. If the spectrum does not meet all criteria (Table 3), the MS must be returned and adjusted to meet all criteria before proceeding with the continuing calibration check.

10.3.2 Purge a CAL solution and analyze with the same conditions used during the initial calibration. Selection of the conc entration level of the calibration check standard should be varied so that the ca libration is verified at more than one point over the course of several days.

10.3.3 Demonstrate acceptable performance for the criteria shown in Sect. 10.2.4.

10.3.4 Determine that the absolute areas of the quantitation ions of the internal standard and surrogates have not decreased by more than 30% from the areas measured in the most recent continuing calibration check, or by more than 50% from the areas measured duri ng initial calibration. If these areas have decreased by more than these amounts, adjustments must be made to restore system sensitivity. These adjustments may require cleaning of the MS

### 524.2-20 ion source, or other maintenance as indicated in Sect. 10.3.6, and recalibration. Control charts are useful aids in documenting system sensitivity changes.

10.3.5 Calculate the RF for each analyte of concern and surrogate compound from the data measured in the continuing calibration check. The RF for each analyte and surrogate must be within 30% of the mean value measured in the initial calibration. Alternatively, if a linear or second order regression is used, the concentration measured using the calibration curve must be within 30% ofthe true value of the concentration in the calibration solution. If these conditions do not exist, remedial action must be taken which may require recalibration. All data from field samp les obtained after the last successful calibration check standard, should be considered suspect. After remedial action has been taken, duplicate samples should be analyzed if they are available.

10.3.6 Some possible remedial actions. Major maintenance such as cleaning an ionsource, cleaning quadrupole rods, etc. require returning to the initial calibration step.

10.3.6.1 Check and adjust GC and/or MS operating conditions; check the MS resolution, and calibrate the mass scale.

10.3.6.2 Clean or replace the splitless injection liner; silanize a new injection liner. This applies only if the injection liner is an integral part of the system.

10.3.6.3 Flush the GC column with solvent according to manufacturer's instructions.

10.3.6.4 Break off a short portion (about 1 meter) of the column from the end near the injector; or replace GC column. This action will cause a slight change in retention times. Analyst may need to redefine retention windows.

10.3.6.5 Prepare fresh CAL solutions, and repeat the initial calibration step.

10.3.6.6 Clean the MS ion source and rods (if a quadrupole).

10.3.6.7 Replace any components that allow analytes to come into contact with hot metal surfaces.

10.3.6.8 Replace the MS electron multiplier, or any other faulty components.

10.3.6.9 Replace the trap, especially when only a few compounds fail the criteria in Sect. 10.3.5 while the majority are determined success-

### 524.2-21 fully. Also check for gas leaks in the purge and trap unit as well as the rest of the analytical system.

10.4 Optional calibration for vinyl chloride usin g a certified gaseous mixture of vinyl chloride in nitrogen can be accomplished by the following steps.

10.4.1 Fill the purging device with 25.0 mL (or 5-mL) of reagent water or aqueous calibration standard.

10.4.2 Start to purge the aqueous mixture. Inject a known volume (between 100 and 2000 

### : L) of the calibration gas (at room temperature) directly into the purging device with a gas tight syringe. Slowly inject the gaseous sample through a septum seal at the top of the purging device at 2000 

### : L/min. If the injection of the standard is made through the aqueous sample inlet port, flush the dead volume with several mL of room air or carrier gas. Inject the gaseous standard before 5 min of the 11-min purge time have elapsed.

10.4.3 Determine the aqueous equivalent concentration of vinyl chloride standard, in 

### : g/L, injected with one of the following equations:

5 mL samples, S = 0.51 (C)(V) 25 mL samples, S = 0.102 (C)(V)

where S = Aqueous equivalent concentration of vinyl chloride standard in 

### : g/L; C = Concentration of gaseous standard in mg/L (v/v); V = Volume of standard injected in mL.

11. PROCEDURE

11.1 SAMPLE INTRODUCTION AND PURGING

11.1.1 This method is designed for a 25-mL or 5-mL sample volume, but a smaller (5 mL) sample volume is recommended if the GC/MS system has adequate sensitivity to achieve the required method detection limits. Adjust the helium purge gas flow rate to 40 mL/min. Attach the trap inlet to the purging device and open the syringe valve on the purging device.

11.1.2 Remove the plungers from two 25-mL (or 5-mL depending on sample size) syringes and attach a closed syringe va lve to each. Warm the sample to room temperature, open the sample bottle, and carefully pour the sample into one of the syringe barrels to just short of overflowing. Replace the syringe plunger, invert the syringe, and compress the sample. Open the syringe valve and vent any residual air while adjusting the sample volume to 25.0-mL (or 5-mL). To all samples, blanks, and calibration standards, add 5- 

### : L (or an appropriate volume) of the fortification solution containing the internal standard and the surrogates to the sample through the syringe valve. Close the valve. Fill the

### 524.2-22 second syringe in an identical manner from the same sample bottle. Reserve this second syringe for a reanalysis if necessary.

11.1.3 Attach the sample syringe valve to the syringe valve on the purging device. Be sure that the trap is cooler than 25 o C, then open the sample syringe valve and inject the sample into the purging chamber. Close both valves and initiate purging. Purge the sample for 11.0 min at ambient temperature.

11.1.4 Standards and samples must be analyzed in exactly the same manner. Room temperature must be reasonably constant, and changes in excess of 10°F will adversely affect the accuracy and precision of the method.

11.2 SAMPLE DESORPTION

11.2.1 Non-cryogenic interface -- After the 11-min purge, place the purge and trap system in the desorb mode and preheat the trap to 180 o C without a flow of desorption gas. Then simultaneously start the flow of desorption gas at a flow rate suitable for the column being used (optimum desorb flow rate is 15 mL/min) for about 4 min, begin the GC temperature program, and start data acquisition.

11.2.2 Cryogenic interface -- After the 11-min purge, place the purge and trap system in the desorb mode, make sure the cryogenic interface is a -150 o C or lower, and rapidly heat the trap to 180 o C while backflushing with an inert gas at 4 mL/min for about 5 min. At the end of the 5 min desorption cycle, rapidly heat the cryogenic trap to 250 o C, and simultaneously begin the temperature program of the gas chromatograph, and start data acquisition.

11.2.3 While the trapped components are being introduced into the gas chromatograph (or cryogenic interface), empty the purging device using the sample syringe and wash the chamber with two 25-mL flushes of reagent water. After the purging device has been emptied, leave syringe valve open to allow the purge gas to vent through the sample introduction needle.

11.3 GAS CHROMATOGRAPHY/MASS SPECTROMETRY -- Acquire and store data over the nominal mass range 35-260 with a total cycle time (including scan overhead time) of 2 sec or less. If water, methanol, or carbon dioxide cause a background problem, start at 47 or 48 m/z. If ketones are to be determined, data must be acquired starting at m/z 43. Cycle time must be adjusted to meas ure five or more spectra during the elution of each GC peak. Suggested temperature programs are provided below. Alternative temperature programs can be used.

11.3.1 Single ramp linear temperature program for wide bore column 1 and 2 with a jet separator. Adjust the helium carrier gas flow rate to within the capacity of the separator, or about 15 mL/min. The column temperature is reduced 10 o C and held for 5 min from the beginning of desorption, then programmed to 160 o C at 6 o C/min, and held until all components have eluted.

### 524.2-23 11.3.2 Multi-ramp temperature program for wide bore column 2 with the open split interface. Adjust the helium carrier ga s flow rate to about 4.6 mL/min. The column temperature is reduced to 10 o C and held for 6 min from the beginning of desorption, then heated to 70 o C at 10 o /min, heated to 120 o C at 5 o /min, heated to 180 o at 8 o /min, and held at 180 o until all compounds have eluted.

11.3.3 Single ramp linear temperature program for narrow bore column 3 with a cryogenic interface. Adjust the heliu m carrier gas flow rate to about 4 mL/min. The column temperature is reduced to 10°C and held for 5 min from the beginning of vaporization from th e cryogenic trap, programmed at 6°/min for 10 min, then 15°/min for 5 min to 145°C, and held until all components have eluted.

11.3.4 Multi-ramp temperature program for wide bore column 4 with the open split interface. Adjust the helium carrier ga s flow rate to about 7.0 mL/min. The column temperature is - 10°C and held for 6 min. from beginning of desorption, then heated to 100°C at 10°C/min, heated to 200°C at 5°C/min and held at 200°C for 8 min or until all compounds of interest had eluted.

11.4 TRAP RECONDITIONING -- After desorbing the sample for 4 min, recon-dition the trap by returning the purge and trap system to the purge mode. Wait 15 sec, then close the syringe valve on the purging device to begin gas flow through the trap. Maintain the trap temperature at 180 o C. Maintain the moisture control module, if utilized, at 90°C to remove residual water. After approxim ately 7 min, turn off the trap heater and open the syringe valve to stop the gas flow th rough the trap. When the trap is cool, the next sample can be analyzed.

11.5 TERMINATION OF DATA ACQUISITION -- When all the sample components have eluted from the GC, terminate MS data ac quisition. Use appropriate data output software to display full range mass spectra an d appropriate plots of ion abundance as a function of time. If any ion abundance exceeds the system working range, dilute the sample aliquot in the second syringe with reagent water and analyze the diluted aliquot.

11.6 IDENTIFICATION OF ANALYTES -- Identify a sample component by comparison of its mass spectrum (after background subtraction) to a reference spectrum in the user-created data base. The GC retention time of the sample component should be within three standard deviations of the mean retention time of the compound in the calibration mixture.

11.6.1 In general, all ions that are pres ent above 10% relative abundance in the mass spectrum of the standard should be present in the mass spectrum of the sample component and should agree within absolute 20%. For example, if an ion has a relative abundance of 30% in the standard spectrum, its abundance in the sample spectrum should be in the range of 10 to 50%. Some ions, particularly the molecular ion, are of special importance, and should be evaluated even if they are below 10% relative abundance.

### 524.2-24 11.6.2 Identification requires expert judgment when sample components are not resolved chromatographically and produce mass spectra containing ions contributed by more than one analyte. When GC peaks obviously represent more than one sample component (i.e., broadened peak with shoulder(s) orvalley between two or more maxima), appropriate analyte spectra and background spectra can be selected by examining plots of characteristic ions for tentatively identified components. When analytes coelute (i.e., only one GC peak is apparent), the identification criteria can be met but each analyte spectrum will contain extraneous ions contributed by the coeluting compound. Because purgeable organic compounds are relatively small molecules and produce comparatively simple mass spectra, this is not a significant problem for most method analytes.

11.6.3 Structural isomers that produce very similar mass spectra can be explicitly identified only if they have sufficientl y different GC retention times. Acceptable resolution is achieved if the height of the valley between two peaks is less than 25% of the average height of the two peaks. Otherwise, structural isomers are identified as isomeric pair s. Two of the three isomeric xylenes and two of the three dichlorobenzenes ar e examples of structural isomers that may not be resolved on the capillary columns. If unresolved, these groups of isomers must be reported as isomeric pairs.

11.6.4 Methylene chloride, acetone, carbon disulfide, and other background components appear in variable quantities in laboratory and field reagent blanks, and generally cannot be accurately measured. Subtraction of the concentration in the blank from the concentration in the sample is not acceptable because the concentration of the background in the blank is highly variable.

12. DATA ANALYSIS AND CALCULATIONS

12.1 Complete chromatographic resolution is not necessary for accurate and precise measurements of analyte concentrations if unique ions with adequate intensities are available for quantitation. If the response for any analyte exceeds the linear range of the calibration established in Section 10, obtain and dilute a duplicate a duplicate sample. Do not extrapolate beyond the calibration range.

12.1.1 Calculate analyte and surrogate concentrations, using the multi-point calibration established in Section 10. Do not use the daily calibration verification data to quantitate analytes in samples.

(A
x )(Q is ) 1000 C
x = (A is ) RF V

where: C
x = concentration of analyte or surrogate in 

### : g/L in the water sample. A
x = integrated abundance of the quantitation ion of the analyte in the sample. A is = integrated abundance of the quantitation ion

### 524.2-25 of the internal standard in the sample. Q is = total quantity (in micrograms) of internal standard added to the water sample. V = original water sample volume in mL. RF = mean response factor of analyte from the initial calibration.

12.1.2 Alternatively, use the GC/MS system software or other available proven software to compute the concentrations of the analytes and surrogates from the linear or second order regression curve established in Section 10. Do not use the daily calibration verification da ta to quantitate analytes in samples.

12.1.3 Calculations should utilize all available digits of precision, but final reported concentrations should be rounded to an appropriate number of significant figures (one digit of uncertainty). Experience indicates that three significant figures may be used for concentrations above 99 

### : g/L, two significant figures for concentrations between 1- 99 

### : g/L, and one significant figure for lower concentrations.

12.1.4 Calculate the total trihalomethane concentration by summing the four individual trihalomethane concentrations.

13. METHOD PERFORMANCE

13.1 Single laboratory accuracy and precision data were obtained for the method analytes using laboratory fortified blanks with an alytes at concentrations between 0.1 and 5 

### : g/L. Results were obtained using the four columns specified (Sect. 6.3.2.1) and the open split or jet separator (Sect. 6.3.3.1), or the cryogenic interface (Sect. 6.3.3.2). These data are shown in Tables 4-8.

13.2 With these data, method detection limit s were calculated using the formula (3):

MDL = S t (n-1,1-alpha = 0.99)

where:

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

n = number of replicates

S = the standard deviation of the replicate analyses.

14. POLLUTION PREVENTION

14.1 No solvents are utilized in this method ex cept the extremely small volumes of methanol needed to make calibration standards. Th e only other chemicals used in this method

### 524.2-26 are the neat materials in preparing standards and sample preservatives. All are used in extremely small amounts and pose no threat to the environment.

15. WASTE MANAGEMENT

15.1 There are no waste management issues involved with this method. Due to the nature of this method, the discarded samples ar e chemically less contaminated than when they were collected.

16. REFERENCES

1. J.W. Munch, J.W. Eichelberger, "Evaluation of 48 Compounds for Possible Inclusion in USEPA Method 524.2, Revision 3.0: Expansio n of the Method Analyte List to a Total of 83 Compounds", J. Chro. Sci. ,30 , 471,1992.

2. C. Madding, "Volatile Organic Compounds in Water by Purge and Trap Capillary Column GC/MS," Proceedings of the Water Quality Technology Conference, American Water Works Association, Denver, CO, December 1984.

3. J.A. Glaser, D.L. Foerst, G.D. McKee, S.A. Quave, and W.L. Budde, "Trace Analyses for Wastewaters", Environ . Sci . Technol ., 15 , 1426, 1981.

4. "Carcinogens-Working with Carcinogens," Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Publication No. 77-206, August 1977.

5. "OSHA Safety and Health Standards, Ge neral Industry," (29CFR1910), Occupational Safety and Health Administration, OSHA 2206, (Revised, January 1976).

6. "Safety in Academic Chemistry Laboratories ," American Chemical Society Publication, Committee on Chemical Safety, 3rd Edition, 1979.

7. R.F. Arrendale, R.F. Severson, and O.T. Chortyk, "Open Split Interface for Capillary Gas Chromatography/Mass Spectrometry," Anal . Chem . 1984, 56 , 1533.

8. J.J. Flesch, P.S. Fair, "The Analysis of Cy anogen Chloride in Drinking Water," Proceedings of Water Quality Technology Conference, American Water Works Association, St. Louis, MO., November 14-16, 1988.

### 524.2-27 17. TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA

TABLE 1. MOLECULAR WEIGHTS AND QUANTITATION IONS FOR METHOD ANALYTES

Primary Secondary Quantitation Quantitation Compound MW a Ion Ions

Internal standard

Fluorobenzene 96 96 77

Surrogates

4-Bromofluorobenzene 174 95 174,176 1,2-Dichlorobenzene-d4 150 152 115,150

Target Analytes

Acetone 58 43 58 Acrylonitrile 53 52 53 Allyl chloride 76 76 49 Benzene 78 78 77 Bromobenzene 156 156 77,158 Bromochloromethane 128 128 49,130 Bromodichloromethane 162 83 85,127 Bromoform 250 173 175,252 Bromomethane 94 94 96 2-Butanone 72 43 57,72 n-Butylbenzene 134 91 134 sec-Butylbenzene 134 105 134 tert-Butylbenzene 134 119 91 Carbon disulfide 76 76 -- Carbon tetrachloride 152 117 119 Chloroacetonitrile 75 48 75 Chlorobenzene 112 112 77,114 1-Chlorobutane 92 56 49 Chloroethane 64 64 66 Chloroform 118 83 85 Chloromethane 50 50 52 2-Chlorotoluene 126 91 126 4-Chlorotoluene 126 91 126 Dibromochloromethane 206 129 127 1,2-Dibromo-3-Chloropropane 234 75 155,157 1,2-Dibromoethane 186 107 109,188 Dibromomethane 172 93 95,174 1,2-Dichlorobenzene 146 146 111,148 1,3-Dichlorobenzene 146 146 111,148 1,4-Dichlorobenzene 146 146 111,148

### 524.2-28 TABLE 1. (continued)

Primary Secondary Quantitation Quantitation Compound MW a Ion Ions

trans-1,4-Dichloro-2-butene 124 53 88,75 Dichlorodifluoromethane 120 85 87 1,1-Dichloroethane 98 63 65,83 1,2-Dichloroethane 98 62 98 1,1-Dichloroethene 96 96 61,63 cis-1,2-Dichloroethene 96 96 61,98 trans-1,2-Dichloroethene 96 96 61,98 1,2-Dichloropropane 112 63 112 1,3-Dichloropropane 112 76 78 2,2-Dichloropropane 112 77 97 1,1-Dichloropropene 110 75 110,77 1,1-Dichloropropanone 126 43 83 cis-1,3-dichloropropene 110 75 110 trans-1,3-dichloropropene 110 75 110 Diethyl ether 74 59 45,73 Ethylbenzene 106 91 106 Ethyl methacrylate 114 69 99 Hexachlorobutadiene 258 225 260 Hexachloroethane 234 117 119,201 2-Hexanone 100 43 58 Isopropylbenzene 120 105 120 4-Isopropyltoluene 134 119 134,91 Methacrylonitrile 67 67 52 Methyl acrylate 86 55 85 Methylene chloride 84 84 86,49 Methyl iodide 142 142 127 Methylmethacrylate 100 69 99 4-Methyl-2-pentanone 100 43 58,85 Methyl-t-butyl ether 88 73 57 Naphthalene 128 128 -- Nitrobenzene 123 51 77 2-Nitropropane 89 46 -- Pentachloroethane 200 117 119,167 Propionitrile 55 54 -- n-Propylbenzene 120 91 120 Styrene 104 104 78 1,1,1,2-Tetrachloroethane 166 131 133,119 1,1,2,2-Tetrachloroethane 166 83 131,85 Tetrachloroethene 164 166 168,129 Tetrahydrofuran 72 71 72,42 Toluene 92 92 91 1,2,3-Trichlorobenzene 180 180 182 1,2,4-Trichlorobenzene 180 180 182 1,1,1-Trichloroethane 132 97 99,61 1,1,2-Trichloroethane 132 83 97,85

### 524.2-29 TABLE 1. (continued)

Primary Secondary Quantitation Quantitation Compound MW a Ion Ions

Trichloroethene 130 95 130,l32 Trichlorofluoromethane 136 101 103 1,2,3-Trichloropropane 146 75 77 1,2,4-Trimethylbenzene 120 105 120 1,3,5-Trimethylbenzene 120 105 120 Vinyl Chloride 62 62 64 o-Xylene 106 106 91 m-Xylene 106 106 91 p-Xylene 106 106 91

a Monoisotopic molecular weight calculated from the atomic masses of the isotopes with the smallest masses.

### 524.2-30 TABLE 2. CHROMATOGRAPHIC RETENTION TIMES FOR METHOD ANALYTES ON THREE COLUMNS WITH FOUR SETS OF CONDITIONS a

Retention Time (min:sec) Compound Col. 1 b Col. 2 b Col. 2 c Col. 3 d Col. 4 e

Internal standard

Fluorobenzene 8:49 6:27 14:06 8:03 22:00

Surrogates

4-Bromofluorobenzene 18:38 15:43 23:38 31:21 1,2-Dichlorobenzene-d4 22:16 19:08 27:25 35:51

Target Analytes

Acetone 16:14 Acrylonitrile 17:49 Allyl chloride 16:58 Benzene 8:14 5:40 13:30 7:25 21:32 Bromobenzene 18:57 15:52 24:00 16:25 31:52 Bromochloromethane 6:44 4:23 12:22 5:38 20:20 Bromodichloromethane 10: 35 8:29 15:48 9:20 23:36 Bromoform 17:56 14:53 22:46 15:42 30:32 Bromomethane 2:01 0:58 4:48 1:17 12:26 2-Butanone 19:41 n-Butylbenzene 22:13 19:29 27:32 17:57 35:41 sec-Butylbenzene 20:47 18:05 26:08 17:28 34:04 tert-Butylbenzene 20:17 17:34 25:36 17:19 33:26 Carbon Disulfide 16:30 Carbon Tetrachloride 7:37 5:16 13:10 7:25 21:11 Chloroacetonitrile 23:51 Chlorobenzene 15:46 13:01 20:40 14:20 28:26 1-Chlorobutane 21:00 Chloroethane 2:05 1:01 1:27 Chloroform 6:24 4:48 12:36 5:33 20:27 Chloromethane 1:38 0:44 3:24 0:58 9:11 2-Chlorotoluene 19:20 16:25 24:32 16:44 32:21 4-Chlorotoluene 19:30 16:43 24:46 16:49 32:38 Cyanogen chloride (8) 1:03 Dibromochloromethane 14:23 11:51 19:12 12:48 26:57 1,2-Dibromo-3-Chloropropane 24:32 21:05 18:02 38:20 1,2-Dibromoethane 14:44 11:50 19:24 13:36 27:19 Dibromomethane 10:39 7:56 15:26 9:05 23:22 1,2-Dichlorobenzene 22:31 19:10 27:26 17:47 35:55 1,3-Dichlorobenzene 21:13 18:08 26:22 17:28 34:31 1,4-Dichlorobenzene 21:33 18:23 26:36 17:38 34:45 t-1,4-Dichloro-2-butene 31:44 Dichlorodifluoromethane 1: 33 0:42 3:08 0:53 7:16 1,1-Dichloroethane 4:51 2:56 10:48 4:02 18:46

### 524.2-31 TABLE 2. (continued)

Retention Time (min:sec) Compound Col. 1 b Col. 2 b Col. 2 c Col. 3 d Col. 4 e

1,2-Dichloroethane 8:24 5:50 13:38 7:00 21:31 1,1-Dichloroethene 2:53 1:34 7:50 2:20 16:01 cis-1,2-Dichloroethene 6:11 3:54 11:56 5:04 19:53 trans-1,2-Dichloroethene 3:59 2:22 9:54 3:32 17:54 1,2-Dichloropropane 10:05 7:40 15:12 8:56 23:08 1,3-Dichloropropane 14:02 11:19 18:42 12:29 26:23 2,2-Dichloropropane 6:01 3:48 11:52 5:19 19:54 1,1-Dichloropropanone 24:52 1,1-Dichloropropene 7:49 5:17 13:06 7:10 21:08 cis-1,3-dichloropropene 11.58 16:42 24:24 trans-1,3-dichloropropene 13.46 17:54 25:33 Diethyl ether 15:31 Ethylbenzene 15:59 13:23 21:00 14:44 28:37 Ethyl Methacrylate 25:35 Hexachlorobutadiene 26:59 23:41 32:04 19:14 42:03 Hexachloroethane 36:45 Hexanone 26:23 Isopropylbenzene 18:04 15:28 23:18 16:25 30:52 4-Isopropyltoluene 21:12 18:31 26:30 17:38 34:27 Methacrylonitrile 20:15 Methylacrylate 20:02 Methylene Chloride 3:36 2:04 9:16 2:40 17:18 Methyl Iodide 16:21 Methylmethacrylate 23:08 4-Methyl-2-pentanone 24:38 Methyl-t-butyl ether 17:56 Naphthalene 27:10 23:31 32:12 19:04 42:29 Nitrobenzene 39:02 2-Nitropropane 23:58 Pentachloroethane 33:33 Propionitrile 19:58 n-Propylbenzene 19:04 16:25 24:20 16:49 32:00 Styrene 17:19 14:36 22:24 15:47 29:57 1,1,1,2-Tetrachloroethane 15:56 13:20 20:52 14:44 28:35 1,1,2,2-Tetrachloroethane 18:43 16:21 24:04 15:47 31:35 Tetrachloroethene 13:44 11:09 18:36 13:12 26:27 Tetrahydrofuran 20:26 Toluene 12:26 10:00 17:24 11:31 25:13 1,2,3-Trichlorobenzene 27:47 24:11 32:58 19:14 43:31 1,2,4-Trichlorobenzene 26:33 23:05 31:30 18:50 41:26 1,1,1-Trichloroethane 7:16 4:50 12:50 6:46 20:51 1,1,2-Trichloroethane 13:25 11:03 18:18 11:59 25:59 Trichloroethene 9:35 7:16 14:48 9:01 22:42 Trichlorofluoromethane 2: 16 1:11 6:12 1:46 14:18 1,2,3-Trichloropropane 19:01 16:14 24:08 16:16 31:47 1,2,4-Trimethylbenzene 20:20 17:42 31:30 17:19 33:33

### 524.2-32 TABLE 2. (continued)

Retention Time (min:sec) Compound Col. 1 b Col. 2 b Col. 2 c Col. 3 d Col. 4 e

1,3,5-Trimethylbenzene 19:28 16:54 24:50 16:59 32:26 Vinyl chloride 1:43 0:47 3:56 1:02 10:22 o-Xylene 17:07 14:31 22:16 15:47 29:56 m-Xylene 16:10 13:41 21:22 15:18 28:53 p-Xylene 16:07 13:41 21:18 15:18 28:53

a Columns 1-4 are those given in Sect. 6.3.2.1; retention times were measured from the beginning of thermal desorption from the trap (columns 1-2, and 4) or from the beginning of thermal release from the cryogenic interface (column 3).

b GC conditions given in Sect. 11.3.1.

c GC conditions given in Sect. 11.3.2.

d GC conditions given in Sect. 11.3.3.

e GC conditions given in Sect. 11.3.4.

### 524.2-33 TABLE 3. ION ABUNDANCE CRITERIA FOR 4-BROMOFLUOROBENZENE (BFB)

Mass (M/z) Relative Abundance Criteria

50 15 to 40% of mass 95 75 30 to 80% of mass 95 95 Base Peak, 100% Relative Abundance 96 5 to 9% of mass 95 173 < 2% of mass 174 174 > 50% of mass 95 175 5 to 9% of mass 174 176 > 95% but < 101% of mass 174 177 5 to 9% of mass 176

### 524.2-34 TABLE 4. ACCURACY AND PRECISION DATA FROM 16-31 DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY COLUMN 1 a

Compound True Conc. Range ( 

### : g/L) Mean Accuracy (% of True

Value) Rel. Std. Dev. (%) Method Det. Limit b ( 

### : g/L)

Benzene Bromobenzene Bromochloromethane Bromodichloromethane Bromoform Bromomethane n-Butylbenzene sec-Butylbenzene tert-Butylbenzene Carbon Tetrachloride Chlorobenzene Chloroethane Chloroform Chloromethane 2-Chlorotoluene 4-Chlorotoluene Dibromochloromethane 1,2-Dibromo-3-Chloropropane 1,2-Dibromoethane Dibromomethane 1,2-Dichlorobenzene 1,3-Dichlorobenzene 1,4-Dichlorobenzene Dichlorodifluoromethane 1,1-Dichloroethane 1,2-Dichloroethane 1,1-Dichloroethene cis-1,2-Dichloroethene trans-1,2-Dichloroethene 1,2-Dichloropropane 1,3-Dichloropropane 2,2-Dichloropropane 1,1-Dichloropropene cis-1,2-Dichloropropene trans-1,2-Dichloropropene Ethylbenzene Hexachlorobutadiene Isopropylbenzene 4-Isopropyltoluene 0.1-10 0.1-10 0.5-10 0.1-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.1-10 0.5-10 0.5-10 0.5-10 0.1-10 0.1-10 0.1-10 0.5-10 0.5-10 0.5-10 0.1-10 0.5-10 0.2-20 0.5-10 0.5-10 0.1-10 0.1-10 0.5-10 0.1-10 0.1-10 0.1-10 0.5-10 0.5-10

0.1-10 0.5-10 0.5-10 0.1-10 97 100

90 95 101

95 100 100 102

84 98 89 90 93 90 99 92 83 102 100

93 99 103

90 96 95 94 101

93 97 96 86 98

99 100 101

99 5.7 5.5 6.4 6.1 6.3 8.2 7.6 7.6 7.3 8.8 5.9 9.0 6.1 8.9 6.2 8.3 7.0 19.9

3.9 5.6 6.2 6.9 6.4 7.7 5.3 5.4 6.7 6.7 5.6 6.1 6.0 16.9

8.9

8.6 6.8 7.6 6.7 0.04 0.03 0.04 0.08 0.12 0.11 0.11 0.13 0.14 0.21 0.04 0.10 0.03 0.13 0.04 0.06 0.05 0.26 0.06 0.24 0.03 0.12 0.03 0.10 0.04 0.06 0.12 0.12 0.06 0.04 0.04 0.35 0.10

0.06 0.11 0.15 0.12TABLE 4. ACCURACY AND PRECISION DATA FROM 16-31 DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY COLUMN 1 a

Compound True Conc. Range ( 

### : g/L) Mean Accuracy (% of True

Value) Rel. Std. Dev. (%) Method Det. Limit b ( 

### : g/L)



### 524.2-35 Methylene Chloride Naphthalene n-Propylbenzene Styrene 1,1,1,2-Tetrachloroethane 1,1,2,2-Tetrachloroethane Tetrachloroethene Toluene 1,2,3-Trichlorobenzene 1,2,4-Trichlorobenzene 1,1,1-Trichloroethane 1,1,2-Trichloroethane Trichloroethene Trichlorofluoromethane 1,2,3-Trichloropropane 1,2,4-Trimethylbenzene 1,3,5-Trimethylbenzene Vinyl Chloride o-Xylene m-Xylene p-Xylene 0.1-10 0.1-100 0.1-10 0.1-100 0.5-10 0.1-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.5-10 0.1-31 0.1-10 0.5-10 95 104 100 102

90 91 89 102 109 108

98 104

90 89 108

99 92 98 103

97 104 5.3 8.2 5.8 7.2 6.8 6.3 6.8 8.0 8.6 8.3 8.1 7.3 7.3 8.1 14.4

8.1 7.4 6.7 7.2 6.5 7.7 0.03 0.04 0.04 0.04 0.05 0.04 0.14 0.11 0.03 0.04 0.08 0.10 0.19 0.08 0.32 0.13 0.05 0.17 0.11 0.05 0.13

a Data obtained by using Column 1 with a jet separator interface and a quadrupole mass spectrometer (Section 11.3.1) with analytes divided among three solutions.

b Replicate samples at the lowest concentration listed in Column 2 of this table were analyzed. These results were used to calculate MDLs.

### 524.2-36 TABLE 5. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING THE CRYOGENIC TRAPPING OPTION AND A NARROW-BORE CAPILLARY COLUMN 3 a

Compound True Conc. ( 

### : g/L) Mean Accuracy (% of True

Value) Rel. Std. Dev. (%) Method Det. Limit ( 

### : g/L)

Benzene Bromobenzene Bromochloromethane Bromodichloromethane Bromoform Bromomethane n-Butylbenzene sec-Butylbenzene tert-Butylbenzene Carbon Tetrachloride Chlorobenzene Chloroethane Chloroform Chloromethane 2-Chlorotoluene 4-Chlorotoluene Cyanogen Chloride b Dibromochloromethane 1,2-Dibromo-3-Chloropropane 1,2-Dibromoethane Dibromomethane 1,2-Dichlorobenzene 1,3-Dichlorobenzene 1,4-Dichlorobenzene Dichlorodifluoromethane 1,1-Dichloroethane 1,2-Dichloroethane 1,1-Dichloroethene cis-1,2-Dichloroethene trans-1,2-Dichloroethene 1,2-Dichloropropane 1,3-Dichloropropane 2,2-Dichloropropane 1,1-Dichloropropene cis-1,2-Dichloropropene trans-1,2-Dichloropropene Ethylbenzene Hexachlorobutadiene 0.1 0.5 0.5 0.1 0.1 0.1 0.5 0.5 0.5 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 99 97 97 100

99 99 94 90 90 92 91 100

95 99 99 96 92 99 92 97 93 97 99 93 99 98 100

95 100

98 96 99 99 98

99 100 6.2 7.4 5.8 4.6 5.4 7.1 6.0 7.1 2.5 6.8 5.8 5.8 3.2 4.7 4.6 7.0 10.6

5.6 10.0

5.6 6.9 3.5 6.0 5.7 8.8 6.2 6.3 9.0 3.7 7.2 6.0 5.8 4.9 7.4

5.2 6.7 0.03 0.11 0.07 0.03 0.20 0.06 0.03 0.12 0.33 0.08 0.03 0.02 0.02 0.05 0.05 0.05 0.30 0.07 0.05 0.02 0.03 0.05 0.05 0.04 0.11 0.03 0.02 0.05 0.06 0.03 0.02 0.04 0.05 0.02

0.03 0.04TABLE 5. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING THE CRYOGENIC TRAPPING OPTION AND A NARROW-BORE CAPILLARY COLUMN 3 a

Compound True Conc. ( 

### : g/L) Mean Accuracy (% of True

Value) Rel. Std. Dev. (%) Method Det. Limit ( 

### : g/L)



### 524.2-37 Isopropylbenzene 4-Isopropyltoluene Methylene Chloride Naphthalene n-Propylbenzene Styrene 1,1,1,2-Tetrachloroethane 1,1,2,2-Tetrachloroethane Tetrachloroethene Toluene 1,2,3-Trichlorobenzene 1,2,4-Trichlorobenzene 1,1,1-Trichloroethane 1,1,2-Trichloroethane Trichloroethene Trichlorofluoromethane 1,2,3-Trichloropropane 1,2,4-Trimethylbenzene 1,3,5-Trimethylbenzene Vinyl Chloride o-Xylene m-Xylene p-Xylene 0.5 0.5 0.5 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 98 87 97 98 99 96 100 100

96 100

98 91 100

98 96 97 96 96 99 96 94 94 97 6.4 13.0 13.0

7.2 6.6 19.0

4.7 12.0

5.0 5.9 8.9 16.0

4.0 4.9 2.0 4.6 6.5 6.5 4.2 0.2 7.5 4.6 6.1 0.10 0.26 0.09 0.04 0.06 0.06 0.04 0.20 0.05 0.08 0.04 0.20 0.04 0.03 0.02 0.07 0.03 0.04 0.02 0.04 0.06 0.03 0.06

a Data obtained by using Column 3 with a cryogenic interface and a quadrupole mass spectrometer (Section 11.3.3).

b Reference 8.

### 524.2-38 TABLE 6. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY COLUMN 2 a

Compound No. b Mean Accuracy (% of True Value, 2 

### : g/L Conc.) RSD (%) Mean Accuracy (% of True

Value, 0.2 

### : g/L

Conc.) RSD (%)

Internal Standard

Fluorobenzene

Surrogates

4-Bromofluorobenze 1,2-Dichlorobenzene-d 4
Target Analytes

Benzene Bromobenzene Bromochloromethane Bromodichloromethane Bromoform Bromomethane n-Butylbenzene sec-Butylbenzene tert-Butylbenzene Carbon Tetrachloride Chlorobenzene Chloroethane c Chloroform Chloromethane 2-Chlorotoluene 4-Chlorotoluene Dibromochloromethane 1,2-Dibromo-3-Chloropropane c 1,2-Dibromoethane c Dibromomethane 1,2-Dichlorobenzene 1,3-Dichlorobenzene 1,4-Dichlorobenzene Dichlorodifluoromethane 1,1-Dichloroethane 1,2-Dichloroethane 1

2 3

37 38 4 5 6 7 39 40 41 8 42

9 10 43 44 11

13 45 46 47 14 15 16 ñ

98 97

97 102

99 96 89 55 89 102 101

84 104

97 110

91 89 95

99 93 100

98 38 97 102 ñ

1.8 3.2

4.4 3.0 5.2 1.8 2.4 27.

4.8 3.5 4.5 3.2 3.1

2.0 5.0 2.4 2.0 2.7

2.1 2.7 4.0 4.1 25.

2.3 3.8 ñ

96 95

113 101 102 100

90 52 87 100 100

92 103

95

d 108 108 100

95 94 87 94

d 85 100 ñ

1.3 1.7

1.8 1.9 2.9 1.8 2.2 6.7 2.3 2.8 2.9 2.6 1.6

2.1

3.1 4.4 3.0

2.2 5.1 2.3 2.8

3.6 2.1TABLE 6. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY COLUMN 2 a

Compound No. b Mean Accuracy (% of True Value, 2 

### : g/L Conc.) RSD (%) Mean Accuracy (% of True

Value, 0.2 

### : g/L

Conc.) RSD (%)



### 524.2-39 1,1-Dichloroethene cis-1,2-Dichloroethene trans-1,2-Dichloroethene 1,2-Dichloropropane 1,3-Dichloropropane 2,2-Dichloropropane c 1,1-Dichloropropene c cis-1,2-Dichloropropene c trans-1,2-Dichloropropene Ethylbenzene Hexachlorobutadiene Isopropylbenzene 4-Isopropyltoluene Methylene Chloride Naphthalene n-Propylbenzene Styrene 1,1,1,2-Tetrachloroethane 1,1,2,2-Tetrachloroethane Tetrachloroethene Toluene 1,2,3-Trichlorobenzene 1,2,4-Trichlorobenzene 1,1,1-Trichloroethane 1,1,2-Trichloroethane Trichloroethene Trichlorofluoromethane 1,2,3-Trichloropropane 1,2,4-Trimethylbenzene 1,3,5-Trimethylbenzene Vinyl Chloride 17 18 19 20 21

25 48 26 49 50 27 51 52 53 28 29 30 54 55 56 31 32 33 34 35 57 58 36 90 100

92 102

92

96 96 91 103

95

e 93 102

95 99 101

97 105

90 92 94 107

99 81 97 93 88 104 2.2 3.4 2.1 2.2 3.7

1.7 9.1 5.3 3.2 3.6

7.6 4.9 4.4 2.7 4.6 4.5 2.8 5.7 5.2 3.9 3.4 2.9 4.6 3.9 3.1 2.4 3.5 87 89 85 103

93

99 100

88 101

95

e 78 97 104

95 84 92 126

78 83 94 109 106

48 91 106

97 115 3.8 2.9 2.3 2.9 3.2

2.1 4.0 2.4 2.1 3.1

8.3 2.1 3.1 3.8 3.6 3.3 1.7 2.9 5.9 2.5 2.8 2.5 13.

2.8 2.2 3.2 14.TABLE 6. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF THE METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY COLUMN 2 a

Compound No. b Mean Accuracy (% of True Value, 2 

### : g/L Conc.) RSD (%) Mean Accuracy (% of True

Value, 0.2 

### : g/L

Conc.) RSD (%)



### 524.2-40 o-Xylene m-Xylene p-Xylene 59 60 61 97

f 98 1.8

2.3 98

f 103 1.7

1.4

a Data obtained using Column 2 with the open split interface and an ion trap mass spectrometer (Section 11.3.2) with all method anal ytes in the same reagent water solution.

b Designation in Figures 1 and 2.

c Not measured; authentic standards were not available.

d Not found at 0.2 

### : g/L.

e Not measured; methylene chloride was in the laboratory reagent blank.

f m-xylene coelutes with and cannot be distinguished from its isomer p-xylene, No 61.

### 524.2-41 TABLE 7. ACCURACY AND PRECISION DATA FROM SEVEN DETERMINATIONS OF METHOD ANALYTES IN REAGENT WATER USING WIDE-BORE CAPILLARY COLUMN 4 a

Compound True Conc. ( 

### : g/L) Mean Conc. Detected

( 

### : g/L) Rel. Std. Dev. (%) Method Detect.

Limit ( 

### : g/L)

Acetone Acrylonitrile Allyl Chloride 2-Butanone Carbon Disulfide Chloroacetonitrile 1-Chlorobutane trans-Dichloro-2-Butene 1,1-Dichloropropanone cis-1,3-Dichloropropene trans-1,3-Dichloropropene Diethyl Ether Ethyl Methacrylate Hexachloroethane 2-Hexanone Methacrylonitrile Methylacrylate Methyl Iodide Methylmethacrylate 4-Methyl-2-Pentanone Methyl-tert-Butylether Nitrobenzene 2-Nitrobenzene Pentachloroethane Propionitrile Tetrahydrofuran 1.0 1.0 1.0 2.0 0.20 1.0 1.0 1.0 5.0 0.20 0.10 1.0 0.20 0.20 1.0 1.0 1.0 0.20 1.0 0.40 0.40 2.0 1.0 0.20 1.0 5.0 1.6 0.81 0.90 2.7 0.19 0.83 0.87 1.3 4.2 0.20 0.11 0.92 0.23 0.18 1.1 0.92 1.2 0.19 1.0 0.56 0.52 2.1 0.83 0.23 0.87 3.9 5.7 8.7 4.7 5.6 15

4.7 6.6 8.7 7.7 3.1 14

9.5 3.9 10 12

4.2 12

3.1 13

9.7 5.6 18

6.2 20

5.3 13 0.28 0.22 0.13 0.48 0.093 0.12 0.18 0.36 1.0 0.020 0.048 0.28 0.028 0.057 0.39 0.12 0.45 0.019 0.43 0.17 0.090 1.2 0.16 0.14 0.14 1.6

a Data obtained using Column 4 with the open split interface and an ion trap mass spectrometer.

### 524.2-42TABLE 8. ACCURACY AND PRECISION FROM FOUR DETERMINATIONS OF METHOD ANALYTES IN THREE WATER MATRICESFORTIFIED AT 20:G/LaREAGENT WATER RAW WATER TAP WATERCompoundMean(:g/L)Dev.(%)(% of TrueValue)Mean(:g/L)Dev.(%)(% of TrueValue)Mean(:g/L)Dev.(%)(% of TrueValue)AcetoneAcrylonitrileAllyl Chloride2-ButanoneCarbon DisulfideChloroacetonitrile1-Chlorobutanet-1,2-Dichloro-2-Butene1,1-DichloropropanoneDiethyl EtherEthyl MethacrylateHexachloroethane2-HexanoneMethacrylonitrileMethylacrylate19202017192018192018202019202012%4.7%5.1%11%6.4%4.1%6.4%4.1%5.6%6.7%3.7%6.1%6.3%3.4%3.7%95%100%100%85%95%100%90%95%100%90%100%100%95%100%100%2122201918231922222223212123223.7%3.4%2.8%7.3%2.5%4.7%2.2%2.9%6.4%3.4%2.6%2.5%3.8%2.9%3.1%105%110%100%95%90%115%95%110%110%110%115%105%105%115%110%2221191718231721212222212122218.2%1.3%3.5%5.6%3.0%1.3%2.2%0.90%7.7%2.6%1.8%2.0%4.0%2.0%2.1%110%105%95%85%90%115%85%105%105%110%110%105%105%110%105%

### 524.2-43TABLE 8. ACCURACY AND PRECISION FROM FOUR DETERMINATIONS OF METHOD ANALYTES IN THREE WATERMATRICES FORTIFIED AT 20:G/LaReagent WaterRaw WaterTap WaterCompoundMean(:g/L)Dev.(%)(% of TrueValue)Mean(:g/L)Dev.(%)(% of TrueValue)Mean(:g/L)Dev.(%)(% of TrueValue)Methyl IodideMethylmethacrylate4-Methyl-2-PentanoneMethyl-tert-ButyletherNitrobenzene2-NitropropanePentachloroethanePropionitrileTetrahydrofuran2020191920201920204.4%3.7%8.7%3.5%5.4%6.1%5.2%4.5%2.8%100%100%95%95%100%100%95%100%100%1923212222232123243.8%3.3%5.5%2.5%4.8%5.1%2.6%3.9%3.2%95%115%105%110%110%115%105%115%120%1923222221222223213.0%2.7%7.2%3.6%2.4%3.2%1.7%2.4%2.9%95%115%110%110%105%110%110%115%105%aData obtained using Column 4 with the open-split interface and an ion trap mass spectrometer with all Table 8 analyses in the samereagent water solution (1).

### 524.2-44

### 524.2-45

### 524.2-46

### 524.2-47