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6.7.1 Aqueous calibration standards—using a 25 µL syringe, add 20 µL of the secondary standard (Section 6.7) to 50, 100, 200, 500, and 1000 mL of reagent water to produce concentrations of 200, 100, 50, 20, and 10 µg/L, respectively. If the higher concentration standard for the gases and water soluble compounds was chosen (Section 6.6), these compounds will be at concentrations of 1000, 500, 250, 100, and 50 µg/L in the aqueous calibration standards.

6.7.2 Aqueous performance standard—an aqueous standard containing all pollutants, internal standards, labeled compounds, and BFB is prepared daily, and analyzed each shift to demonstrate performance (Section 11). This standard shall contain either 20 or 100 µg/L of the labeled and pollutant gases and water soluble compounds, 10 µg/L BFB, and 20 µg/L of all other pollutants, labeled compounds, and internal standards. It may be the nominal 20 µg/L aqueous calibration standard (Section 6.7.1).

6.7.3 A methanolic standard containing all pollutants and internal standards is prepared to demonstrate recovery of these compounds when syringe injection and purge and trap analyses are compared. This standard shall contain either 100 µg/mL or 500 µg/mL of the gases and water soluble compounds, and 100 µg/mL of the remaining pollutants and internal standards (consistent with the amounts in the aqueous performance standard in 6.7.2).

6.7.4 Other standards which may be needed are those for test of BFB performance (Section 7.1) and for collection of mass spectra for storage in spectral libraries (Section 7.2).

7. Calibration

7.1 Assemble the gas chromatographic apparatus and establish operating conditions given in table 2. By injecting standards into the GC, demonstrate that the analytical system meets the detection limits in table 2 and the mass-intensity criteria in table 3 for 50 ng BFB.

7.2 Mass spectral libraries—detection and identification of the compound of interest are dependent upon the spectra stored in user created libraries.

7.2.1 Obtain a mass spectrum of each pollutant and labeled compound and each internal standard by analyzing an authentic standard either singly or as part of a mixture in which there is no interference between closely eluted components. That only a single compound is present is determined by examination of the spectrum. Fragments not attributable to the compound under study indicate the presence of an interfering compound. Adjust the analytical conditions and scan rate (for this test only) to produce an undistorted spectrum at the GC peak maximum. An undistorted spectrum will usually be obtained if five complete spectra are collected across the upper half of the GC peak. Software algorithms designed to “enhance” the spectrum may eliminate distortion, but may also eliminate authentic m/z's or introduce other distortion.

7.2.3 The authentic reference spectrum is obtained under BFB tuning conditions (Section 7.1 and table 3) to normalize it to spectra from other instruments.

7.2.4 The spectrum is edited by saving the 5 most intense mass spectral peaks and all other mass spectral peaks greater than 10 percent of the base peak. This spectrum is stored for reverse search and for compound confirmation.

7.3 Assemble the purge and trap device. Pack the trap as shown in Figure 2 and condition overnight at 170–180 °C by backflushing with an inert gas at a flow rate of 20–30 mL/min. Condition traps daily for a minimum of 10 minutes prior to use.

7.3.1 Analyze the aqueous performance standard (Section 6.7.2) according to the purge and trap procedure in Section 10. Compute the area at the primary m/z (table 4) for each compound. Compare these areas to those obtained by injecting one µL of the methanolic standard (Section 6.7.3) to determine compound recovery. The recovery shall be greater than 20 percent for the water soluble compounds, and 60–110 percent for all other compounds. This recovery is demonstrated initially for each purge and trap GC/MS system. The test is repeated only if the purge and trap or GC/MS systems are modified in any way that might result in a change in recovery.

7.3.2 Demonstrate that 100 ng toluene (or toluene-d8) produces an area at m/z 91 (or 99) approx one-tenth that required to exceed the linear range of the system. The exact value must be determined by experience for each instrument. It is used to match the calibration range of the instrument to the analytical range and detection limits required.

7.4 Calibration by isotope dilution—the isotope dilution approach is used for the purgeable organic compounds when appropriate labeled compounds are available and when interferences do not preclude the analysis. If labeled compounds are not available, or interferences are present, internal standard methods (Section 7.5 or 7.6) are used. A calibration curve encompassing the concentration range of interest is prepared for each compound determined. The relative response (RR) vs concentration (µg/L) is plotted or computed using a linear regression. An example of a calibration curve for toluene using toluene-d8 is given in figure 5. Also shown are the ±10 percent error limits (dotted lines). Relative response is determined according to the procedures described below. A minimum of five data points are required for calibration (Section 7.4.4).

7.4.1 The relative response (RR) of pollutant to labeled compound is determined from isotope ratio values calculated from acquired data. Three isotope ratios are used in this process:

RX=the isotope ratio measured in the pure pollutant (figure 6A).

Ry=the isotope ratio of pure labeled compound (figure 6B).

Rm=the isotope ratio measured in the analytical mixture of the pollutant and labeled compounds (figure 6C).

The correct way to calculate RR is: RR=(Ry-Rm) (RX+1)/(Rm-RX)(Ry+1) If Rm is not between 2Ry and 0.5RX, the method does not apply and the sample is analyzed by internal or external standard methods (Section 7.5 or 7.6).

7.4.2 In most cases, the retention times of the pollutant and labeled compound are the same and isotope ratios (R's) can be calculated from the EICP areas, where: R=(area at m1/z)/(area at m2/z) If either of the areas is zero, it is assigned a value of one in the calculations; that is, if: area of m1/z=50721, and area of m2/z=0, then R=50721/1=50720. The m/z's are always selected such that RX>Ry. When there is a difference in retention times (RT) between the pollutant and labeled compounds, special precautions are required to determine the isotope ratios.

RX, Ry, and Rm are defined as follows:

RX=[area m1/z (at RT1)]/1

Ry=1/[area m2/z (at RT2)]

Rm=[area m1/z (at RT1)]/[area m2/z (at RT2)]

7.4.3 An example of the above calculations can be taken from the data plotted in figure 6 for toluene and toluene-d8. For these data, RX=168920/1=168900, Ry=1/60960=0.00001640, and Rm=96868/82508=1.174. The RR for the above data is then calculated using the equation given in Section 7.4.1. For the example, RR=1.174.

Note: Not all labeled compounds elute before their pollutant analogs.

7.4.4 To calibrate the analytical system by isotope dilution, analyze a 5 mL aliquot of each of the aqueous calibration standards (Section 6.7.1) spiked with an appropriate constant amount of the labeled compound spiking solution (Section 6.6), using the purge and trap procedure in section 10. Compute the RR at each concentration.

7.4.5 Linearity—if the ratio of relative response to concentration for any compound is constant (less than 20 percent coefficient of variation) over the 5 point calibration range, an averaged relative response/concentration ratio may be used for that compound; otherwise, the complete calibration curve for that compound shall be used over the 5 point calibration range.

7.5 Calibration by internal standard—used when criteria for isotope dilution (Section 7.4) cannot be met. The method is applied to pollutants having no labeled analog and to the labeled compounds. The internal standards used for volatiles analyses are bromochloromethane, 2-bromo-1-chloropropane, and 1,4-dichlorobutane. Concentrations of the labeled compounds and pollutants without labeled analogs are computed relative to the nearest eluted internal standard, as shown in table 2.

7.5.1 Response factors—calibration requires the determination of response factors (RF) which are defined by the following equation:

RF=(AsxCis)/(AisxCs), where As is the EICP area at the characteristic m/z for the compound in the daily standard. Ais is the EICP area at the characteristic m/z for the internal standard.

Cis is the concentration (ug/L) of the internal standard

Cs is the concentration of the pollutant in the daily standard.

7.5.2 The response factor is determined at 10, 20, 50, 100, and 200 ug/L for the pollutants (optionally at five times these concentrations for gases and water soluble pollutants—see Section 6.7), in a way analogous to that for calibration by isotope dilution (Section 7.4.4). The RF is plotted against concentration for each compound in the standard (Cs) to produce a calibration curve.

7.5.3 Linearity—if the response factor (RF) for any compound is constant (less than 35 percent coefficient of variation) over the 5 point calibration range, an averaged response factor may be used for that compound; otherwise, the complete calibration curve for that compound shall be used over the 5 point range.

7.6 Combined calibration—by adding the isotopically labeled compounds and internal standards (Section 6.6) to the aqueous calibration standards (Section 6.7.1), a single set of analyses can be used to produce calibration curves for the isotope dilution and internal standard methods. These curves are verified each shift (Section 11.5) by purging the aqueous performance standard (Section 6.7.2). Recalibration is required only if calibration and on-going performance (Section 11.5) criteria cannot be met.

8. Quality Assurance/Quality Control

8.1 Each laboratory that uses this method is required to operate a formal quality assurance program. The minimum requirements of this program consist of an initial demonstration of laboratory capability, analysis of samples spiked with labeled compounds to evaluate and document data quality, and analysis of standards and blanks as tests of continued performance. Laboratory performance is compared to established performance criteria to determine if the results of analyses meet the performance characteristics of the method.

8.1.1 The analyst shall make an initial demonstration of the ability to generate acceptable accuracy and precision with this method. This ability is established as described in Section 8.2.

8.1.2 The analyst is permitted to modify this method to improve separations or lower the costs of measurements, provided all performance specifications are met. Each time a modification is made to the method, the analyst is required to repeat the procedure in Section 8.2 to demonstrate method performance.

8.1.3 Analyses of blanks are required to demonstrate freedom from contamination and that the compounds of interest and interfering compounds have not been carried over from a previous analysis (Section 3). The procedures and criteria for analysis of a blank are described in Sections 8.5 and 11.7.

8.1.4 The laboratory shall spike all samples with labeled compounds to monitor method performance. This test is described in Section 8.3. When results of these spikes indicate atypical method performance for samples, the samples are diluted to bring method performance within acceptable limits (Section 14.2).

8.1.5 The laboratory shall, on an on-going basis, demonstrate through the analysis of the aqueous performance standard (Section 6.7.2) that the analysis system is in control. This procedure is described in Sections 11.1 and 11.5.

8.1.6 The laboratory shall maintain records to define the quality of data that is generated. Development of accuracy statements is described in Sections 8.4 and 11.5.2.

8.2 Initial precision and accuracy—to establish the ability to generate acceptable precision and accuracy, the analyst shall perform the following operations:

8.2.1 Analyze two sets of four 5–mL aliquots (8 aliquots total) of the aqueous performance standard (Section 6.7.2) according to the method beginning in Section 10.

8.2.2 Using results of the first set of four analyses in Section 8.2.1, compute the average recovery (X ) in µg/L and the standard deviation of the recovery (s) in µg/L for each compound, by isotope dilution for polluitants with a labeled analog, and by internal standard for labeled compounds and pollutants with no labeled analog.

8.2.3 For each compound, compare s and X with the corresponding limits for initial precision and accuracy found in table 5. If s and X for all compounds meet the acceptance criteria, system performance is acceptable and analysis of blanks and samples may begin. If individual X falls outside the range for accuracy, system performance is unacceptable for that compound.

Note: The large number of compounds in table 5 present a substantial probability that one or more will fail one of the acceptance criteria when all compoulds are analyzed. To determine if the analytical system is out of control, or if the failure can be attributed to probability, proceed as follows:

8.2.4 Using the results of the second set of four analyses, compute s and X for only those compounds which failed the test of the first set of four analyses (Section 8.2.3). If these compounds now pass, system performance is acceptable for all compounds and analysis of blanks and samples may begin. If, however, any of the same compounds fail again, the analysis system is not performing properly for the compound(s) in question. In this event, correct the problem and repeat the entire test (Section 8.2.1).

8.3 The laboratory shall spike all samples with labeled compounds to assess method performance on the sample matrix.

8.3.1 Spike and analyze each sample according to the method beginning in Section 10.

8.3.2 Compute the percent recovery (P) of the labeled compounds using the internal standard method (Section 7.5).

8.3.3 Compare the percent recovery for each compound with the corresponding labeled compound recovery limit in table 5. If the recovery of any compound falls outside its warning limit, method performance is unacceptable for that compound in that sample. Therefore, the sample matrix is complex and the sample is to be diluted and reanalyzed, per Section 14.2.

8.4 As part of the QA program for the laboratory, method accuracy for wastewater samples shall be assessed and records shall be maintained. After the analysis of five wastewater samples for which the labeled compounds pass the tests in Section 8.3.3, compute the average percent recovery (P) and the standard deviation of the percent recovery (sp) for the labeled compounds only. Express the accuracy assessment as a percent recovery interval from P-2sp to P+2sp. For example, if P=90% and sp=10%, the accuracy interval is expressed as 70–110%. Update the accuracy assessment for each compound on a regular basis (e.g. after each 5–10 new accuracy measurements).

8.5 Blanks—reagent water blanks are analyzed to demonstrate freedom from carry-over (Section 3) and contamination.

8.5.1 The level at which the purge and trap system will carry greater than 5 µg/L of a pollutant of interest (table 1) into a succeeding blank shall be determined by analyzing successively larger concentrations of these compounds. When a sample contains this concentration or more, a blank shall be analyzed immediately following this sample to demonstrate no carry-over at the 5 µg/L level.

8.5.2 With each sample lot (samples analyzed on the same 8 hr shift), a blank shall be analyzed immediately after analysis of the aqueous performance standard (Section 11.1) to demonstrate freedom from contamination. If any of the compounds of interest (table 1) or any potentially interfering compound is found in a blank at greater than 10 µg/L (assuming a response factor of 1 relative to the nearest eluted internal standard for compounds not listed in table 1), analysis of samples is halted until the source of contamination is eliminated and a blank shows no evidence of contamination at this level.

8.6 The specifications contained in this method can be met if the apparatus used is calibrated properly, then maintained in a calibrated state.

The standards used for calibration (Section 7), calibration verification (Section 11.5) and for initial (Section 8.2) and on-going (Section 11.5) precision and accuracy should be identical, so that the most precise results will be obtained. The GC/MS instrument in particular will provide the most reproducible results if dedicated to the settings and conditions required for the analyses of volatiles by this method.

8.7 Depending on specific program requirements, field replicates may be collected to determine the precision of the sampling technique, and spiked samples may be required to determine the accuracy of the analysis when internal or external standard methods are used.

9. Sample Collection, Preservation, and Handling

9.1 Grab samples are collected in glass containers having a total volume greater than 20 mL. Fill sample bottles so that no air bubbles pass through the sample as the bottle is filled. Seal each bottle so that no air bubbles are entrapped. Maintain the hermetic seal on the sample bottle until time of analysis.

9.2 Samples are maintained at 0–4 °C from the time of collection until analysis. If the sample contains residual chlorine, add sodium thiosulfate preservative (10 mg/40 mL) to the empty sample bottles just prior to shipment to the sample site. EPA Methods 330.4 and 330.5 may be used for measurement of residual chlorine (Reference 8). If preservative has been added, shake bottle vigorously for one minute immediately after filling.

9.3 Experimental evidence indicates that some aromatic compounds, notably benzene, toluene, and ethyl benzene are susceptible to rapid biological degradation under certain environmental conditions. Refrigeration alone may not be adequate to preserve these compounds in wastewaters for more than seven days. For this reason, a separate sample should be collected, acidified, and analyzed when these aromatics are to be determined. Collect about 500 mL of sample in a clean container.

Adjust the pH of the sample to about 2 by adding HCl (1+1) while stirring. Check pH with narrow range (1.4 to 2.8) pH paper. Fill a sample container as described in Section 9.1. If residual chlorine is present, add sodium thiosulfate to a separate sample container and fill as in Section 9.1.

9.4 All samples shall be analyzed within 14 days of collection.

10. Purge, Trap, and GC/MS Analysis

10.1 Remove standards and samples from cold storage and bring to 20–25 °.

10.2 Adjust the purge gas flow rate to 40 ±4 mL/min. Attach the trap inlet to the purging device and set the valve to the purge mode (figure 3). Open the syringe valve located on the purging device sample introduction needle (figure 1).

10.3 Remove the plunger from a 5–mL syringe and attach a closed syringe valve. Open the sample bottle and carefully pour the sample into the syringe barrel until it overflows. Replace the plunger and compress the sample. Open the syringe valve and vent any residual air while adjusting the sample volume to 5.0 mL. Because this process of taking an aliquot destroys the validity of the sample for future analysis, fill a second syringe at this time to protect against possible loss of data. Add an appropriate amount of the labeled compound spiking solution (Section 6.6) through the valve bore, then close the valve.

10.4 Attach the syringe valve assembly to the syringe valve on the purging device. Open both syringe valves and inject the sample into the purging chamber.

10.5 Close both valves and purge the sample for 11.0 ±0.1 minutes at 20–25 °C.

10.6 After the 11 minute purge time, attach the trap to the chromatograph and set the purge and trap apparatus to the desorb mode (figure 4). Desorb the trapped compounds into the GC column by heating the trap to 170–180 °C while backflushing with carrier gas at 20–60 mL/min for four minutes. Start MS data acquisition upon start of the desorb cycle, and start the GC column temperature program 3 minutes later. Table 1 summarizes the recommended operating conditions for the gas chromatograph. Included in this table are retention times and detection limits that were achieved under these conditions. Other columns may be used provided the requirements in Section 8 can be met. If the priority pollutant gases produce GC peaks so broad that the precision and recovery specifications (Section 8.2) cannot be met, the column may be cooled to ambient or sub-ambient temperatures to sharpen these peaks.

10.7 While analysis of the desorbed compounds proceeds, empty the purging chamber using the sample introduction syringe. Wash the chamber with two 5-mL portions of reagent water. After the purging device has been emptied, allow the purge gas to vent through the chamber until the frit is dry, so that it is ready for the next sample.

10.8 After desorbing the sample for four minutes, recondition the trap by returning to the purge mode. Wait 15 seconds, then close the syringe valve on the purging device to begin gas flow through the trap. Maintain the trap temperature at 170–180 °C. After approximately seven minutes, turn off the trap heater and open the syringe valve to stop the gas flow through the trap. When cool, the trap is ready for the next sample.

11. System Performance

11.1 At the beginning of each 8 hr shift during which analyses are performed, system calibration and performance shall be verified for all pollutants and labeled compounds. For these tests, analysis of the aqueous performance standard (Section 6.7.2) shall be used to verify all performance criteria. Adjustment and/or recalibration (per Section 7) shall be performed until all performance criteria are met. Only after all performance criteria are met may blanks and samples be analyzed.

11.2 BFB spectrum validity—the criteria in table 3 shall be met.

11.3 Retention times—the absolute retention times of all compounds shall approximate those given in Table 2.

11.4 GC resolution—the valley height between toluene and toluene-d8 (at m/z 91 and 99 plotted on the same graph) shall be less than 10 percent of the taller of the two peaks.

11.5 Calibration verification and on-going precision and accuracy—compute the concentration of each polutant (Table 1) by isotope dilution (Section 7.4) for those compmunds which have labeled analogs. Compute the concentration of each pollutant (Table 1) which has no labeled analog by the internal standard method (Section 7.5). Compute the concentration of the labeled compounds by the internal standard method. These concentrations are computed based on the calibration data determined in Section 7.

11.5.1 For each pollutant and labeled compound, compare the concentration with the corresponding limit for on-going accuracy in Table 5. If all compmunds meet the acceptance criteria, system performance is acceptable and analysis of blanks and samples may continue. If any individual value falls outside the range given, system performance is unacceptable for that compound.

Note: The large number of compounds in Table 5 present a substantial probability that one or more will fail the acceptance criteria when all compounds are analyzed. To determine if the analytical system is out of control, or if the failure may be attributed to probability, proceed as follows:

11.5.1.1 Analyze a second aliquot of the aqueous performance standard (Section 6.7.2).

11.5.1.2 Compute the concentration for only those compounds which failed the first test (Section 11.5.1). If these compounds now pass, system performance is acceptable for all compounds and analyses of blanks and samples may proceed. If, however, any of the compounds fail again, the measurement system is not performing properly for these compounds. In this event, locate and correct the problem or recalibrate the system (Section 7), and repeat the entire test (Section 11.1) for all compounds.

11.5.2 Add results which pass the specification in 11.5.1.2 to initial (Section 8.2) and previous on-going data. Update QC charts to form a graphic representation of laboratory performance (Figure 7). Develop a statement of accuracy for each pollutant and labeled compound by calculating the average percentage recovery (R) and the standard deviation of percent recovery (sr). Express the accuracy as a recovery interval from R-2sr to R+2sr. For example, if R=95% and sr=5%, the accuracy is 85–105 percent.

12. Qualitative Determination—Accomplished by Comparison of Data from Analysis of a Sample or Blank with Data from Analysis of the Shift Standard (Section 11.1). Identification is Confirmed When Spectra and Retention Times Agree Per the Criteria Below

12.1 Labeled compounds and pollutants having no labeled analog:

12.1.1 The signals for all characteristic masses stored in the spectral library (Section 7.2.4) shall be present and shall maximize within the same two consecutive scans.

12.1.2 Either (1) the background corrected EICP areas, or (2) the corrected relative intensities of the mass spectral peaks at the GC peak maximum shall agree within a factor of two (0.5 to 2 times) for all masses stored in the library.

12.1.3 The retention time relative to the nearest eluted internal standard shall be within ±7 scans or ±20 seconds, whichever is greater.

12.2 Pollutants having a labeled analog:

12.2.1 The signals for all characteristic masses stored in the spectral library (Section 7.2.4) shall be present and shall maximize within the same two consecutive scans.

12.2.2 Either (1) the background corrected EICP areas, or (2) the corrected relative intensities of the mass spectral peaks at the GC peak maximum shall agree within a factor of two for all masses stored in the spectral library.

12.2.3 The retention time difference between the pollutant and its labeled analog shall agree within ±2 scans or ±6 seconds (whichever is greater) of this difference in the shift standard (Section 11.1).

12.3 Masses present in the experimental mass spectrum that are not present in the reference mass spectrum shall be accounted for by contaminant or background ions. If the experimental mass spectrum is contaminated, an experienced spectrometrist (Section 1.4) is to determine the presence or absence of the compound.

13. Quantitative Determination

13.1 Isotope dilution—by adding a known amount of a labeled compound to every sample prior to purging, correction for recovery of the pollutant can be made because the pollutant and its labeled analog exhibit the same effects upon purging, desorption, and gas chromatography. Relative response (RR) values for sample mixtures are used in conjunction with calibration curves described in Section 7.4 to determine concentrations directly, so long as labeled compound spiking levels are constant. For the toluene example given in Figure 6 (Section 7.4.3), RR would be equal to 1.174. For this RR value, the toluene calibration curve given in Figure 5 indicates a concentration of 31.8 µg/L.

13.2 Internal standard—calculate the concentration using the response factor determined from calibration data (Section 7.5) and the following equation:

Concentration =(As × Cis)/(Ais × RF) where the terms are as defined in Section 7.5.1.

13.3 If the EICP area at the quantitation mass for any compound exceeds the calibration range of the system, the sample is diluted by successive factors of 10 and these dilutions are analyzed until the area is within the calibration range.

13.4 Report results for all pollutants and labeled compounds (Table 1) found in all standards, blanks, and samples, in µg/L to three significant figures. Results for samples which have been diluted are reported at the least dilute level at which the area at the quantitation mass is within the calibration range (Section 13.3) and the labeled compound recovery is within the normal range for the Method (Section 14.2).

14. Analysis of Complex Samples

14.1 Untreated effluents and other samples frequently contain high levels (>1000 µg/L) of the compounds of interest and of interfering compounds. Some samples will foam excessively when purged; others will overload the trap/or GC column.

14.2 Dilute 0.5 mL of sample with 4.5 mL of reagent water and analyze this diluted sample when labeled compound recovery is outside the range given in Table 5. If the recovery remains outside of the range for this diluted sample, the aqueous performance standard shall be analyzed (Section 11) and calibration verified (Section 11.5). If the recovery for the labeled compmund in the aqueous performance standard is outside the range given in Table 5, the analytical system is out of control. In this case, the instrumelt shall be repaired, the performance specifications in Section 11 shall be met, and the analysis of the undiluted sample shall be repeated. If the recovery for the aqueous performance standard is within the range given in Table 5, the method does not work on the sample being analyzed and the result may not be reported for regulatory compliance purposes.

14.3 Reverse search computer programs can misinterpret the spectrum of chromatographically unresolved pollutant and labeled compound pairs with overlapping spectra when a high level of the pollutant is present. Examine each chromatogram for peaks greater than the height of the internal standard peaks. These peaks can obscure the compounds of interest.

15. Method Performance

15.1 The specifications for this method were taken from the inter-laboratory validation of EPA Method 624 (reference 9). Method 1624 has been shown to yield slightly better performance on treated effluents than Method 624. Additional method performance data can be found in Reference 10.

References

1. “Performance Tests for the Evaluation of Computerized Gas Chromatography/Mass Spectrometry Equipment and Laboratories,” USEPA, EMSL/Cincinnati, OH 45268, EPA–600/4–80–025 (April 1980).

2. Bellar, T.A. and Lichtenberg, J.J., “Journal American Water Works Association,” 66, 739 (1974).

3. Bellar, T.A. and Lichtenberg, J.J., “Semi-automated Headspace Analysis of Drinking Waters and Industrial Waters for Purgeable Volatile Organic Compounds,” in Measurement of Organic Pollutants Water and Wastewater, C.E. VanHall, ed., American Society for Testing Materials, Philadelphia, PA, Special Technical Publication 686, (1978).

4. “Working with Carcinogens,” DHEW, PHS, NIOSH, Publication 77–206 (1977).

5. “OSHA Safety and Health Standards, General Industry,” 29 CFR part 1910, OSHA 2206, (1976).

6. “Safety in Academic Chemistry Laboratories,” American Chemical Society Publication, Committee on Chemical Safety (1979).

7. “Handbook of Analytical Quality Control in Water and Wastewater Laboratories,” USEPA, EMSL/Cincinnati, OH 45268, EPA–4–79–019 (March 1979).

8. “Methods 330.4 and 330.5 for Total Residual Chlorine,” USEPA, EMSL/Cincinnati, OH 45268, EPA–4–79–020 (March 1979).

9. “EPA Method Study 29 EPA Method 624—Purgeables,” EPA 600/4–84–054, National Technical Information Service, PB84–209915, Springfield, Virginia 22161, June 1984.

10. “Colby, B.N., Beimer, R.G., Rushneck, D.R., and Telliard, W.A., “Isotope Dilution Gas Chromatography-Mass Spectrometry for the Determination of Priority Pollutants in Industrial Effluents,” USEPA, Effluent Guidelines Division, Washington, DC 20460 (1980).


Table 1_Volatile Organic Compounds Analyzed by Isotope Dilution Gc/MS
------------------------------------------------------------------------
CAS
Compound Storet registry EPA-EGD NPDES
------------------------------------------------------------------------
Acetone...................... 81552 67-64-1 516 V ........
Acrolein..................... 34210 107-02-8 002 V 001 V
Acrylonitrile................ 34215 107-13-1 003 V 002 V
Benzene...................... 34030 71-43-2 004 V 003 V
Bromodichloromethane......... 32101 75-27-4 048 V 012 V
Bromoform.................... 32104 75-25-2 047 V 005 V
Bromomethane................. 34413 74-83-9 046 V 020 V
Carbon tetrachloride......... 32102 56-23-5 006 V 006 V
Chlorobenzene................ 34301 108-90-7 007 V 007 V
Chloroethane................. 34311 75-00-3 016 V 009 V
2-chloroethylvinyl ether..... 34576 110-75-8 019 V 010 V
Chloroform................... 32106 67-66-1 023 V 011 V
Chloromethane................ 34418 74-87-3 045 V 021 V
Dibromochloromethane......... 32105 124-48-1 051 V 008 V
1,1-dichloroethane........... 34496 75-34-3 013 V 014 V
1,2-dichloroethane........... 34536 107-06-2 010 V 015 V
1,1-dichloroethene........... 34501 75-35-4 029 V 016 V
Trans-1,2-dichloroethane..... 34546 156-60-5 030 V 026 V
1,2-dichloropropane.......... 34541 78-87-5 032 V 017 V
Cis-1,3-dichloropropene...... 34704 10061-01-5 ........ ........
Trans-1,3-dichloropropene.... 34699 10061-02-6 033 V ........
Diethyl ether................ 81576 60-29-7 515 V ........
P-dioxane.................... 81582 123-91-1 527 V ........
Ethylbenzene................. 34371 100-41-4 038 V 019 V
Methylene chloride........... 34423 75-09-2 044 V 022 V
Methyl ethyl ketone.......... 81595 78-93-3 514 V ........
1,1,2,2-tetrachloroethane.... 34516 79-34-5 015 V 023 V
Tetrachlorethene............. 34475 127-18-4 085 V 024 V
Toluene...................... 34010 108-88-3 086 V 025 V
1,1,1-trichloroethane........ 34506 71-55-6 011 V 027 V
1,1,2-trichloroethane........ 34511 79-00-5 014 V 028 V
Trichloroethene.............. 39180 79-01-6 087 V 029 V
Vinyl chloride............... 39175 75-01-4 088 V 031 V
------------------------------------------------------------------------




Table 2_Gas Chromatography of Purgeable Organic Compounds by Isotope
Dilution GC/MS
------------------------------------------------------------------------
Mean Minimum
EGD Ref retention level (2)
No. Compound EGD time (µg/
(1) No. (sec) L)
------------------------------------------------------------------------
181 Bromochloromethane (I.S.).............. 181 730 10
245 Chloromethane-d3....................... 181 147 50
345 Chloromethane.......................... 245 148 50
246 Bromomethane-d3........................ 181 243 50
346 Bromomethane........................... 246 246 50
288 Vinyl chloride-d3...................... 181 301 50
388 Vinyl chloride......................... 288 304 10
216 Chloroethane-d5........................ 181 378 50
316 Chloroethane........................... 216 386 50
244 Methylene chloride-d2.................. 181 512 10
344 Methylene chloride..................... 244 517 10
616 Acetone-d6............................. 181 554 50
716 Acetone................................ 616 565 50
002 Acrolein............................... 181 566 50
203 Acrylonitrile-d3....................... 181 606 50
303 Acrylonitrile.......................... 203 612 50
229 1,1-dichloroethene-d2.................. 181 696 10
329 1,1-dichloroethene..................... 229 696 10
213 1,1-dichloroethane-d3.................. 181 778 10
313 1,1-dichloroethane..................... 213 786 10
615 Diethyl ether-d10...................... 181 804 50
715 Diethyl ether.......................... 615 820 50
230 Trans-1,2-dichloroethene-d2............ 181 821 10
330 Trans-1,2-dichloroethene............... 230 821 10
614 Methyl ethyl ketone-d3................. 181 840 50
714 Methyl ethyl ketone.................... 614 848 50
223 Chloroform-13C1........................ 181 861 10
323 Chloroform............................. 223 861 10
210 1,2-dichloroethane-d4.................. 181 901 10
310 1,2-dichloroethane..................... 210 910 10
211 1,1,1-trichloroethane-13C2............. 181 989 10
311 1,1,1-trichloroethane.................. 211 999 10
527 p-dioxane.............................. 181 1001 10
206 Carbon tetrachloride-13C1.............. 182 1018 10
306 Carbon tetrachloride................... 206 1018 10
248 Bromodichloromethane-13C1.............. 182 1045 10
348 Bromodichloromethane................... 248 1045 10
232 1,2-dichloropropane-d6................. 182 1123 10
332 1.2-dichloropropane.................... 232 1134 10
233 Trans-1,3-dichloropropene-d4........... 182 1138 10
333 Trans-1,3-dichloropropene.............. 233 1138 10
287 Trichloroethene-13C1................... 182 1172 10
387 Trichloroethene........................ 287 1187 10
204 Benzene-d6............................. 182 1200 10
304 Benzene................................ 204 1212 10
251 Chlorodibromemethane-13C1.............. 182 1222 10
351 Chlorodibromomethane................... 251 1222 10
214 1,1,2-trichloroethane-13C2............. 182 1224 10
314 1,1,2-trichloroethane.................. 214 1224 10
019 2-chloroethylvinyl ether............... 182 1278 10
182 2-bromo-1-chloropropane (I.S.)......... 182 1306 10
247 Bromoform-13C1......................... 182 1386 10
347 Bromoform.............................. 247 1386 10
215 1,1,2,2-tetrachloroethane-d2........... 183 1525 10
315 1,1,2,2-tetrachloroethane.............. 215 1525 10
285 Tetrachloroethene-13C2................. 183 1528 10
385 Tetrachloroethene...................... 285 1528 10
183 1,4-dichlorobutale (int std)........... 183 1555 10
286 Toluene-d8............................. 183 1603 10
386 Toluene................................ 286 1619 10
207 Chlorobenzene-d5....................... 183 1679 10
307 Chlorobenzene.......................... 207 1679 10
238 Ethylbenzene-d10....................... 183 1802 10
338 Ethylbenzene........................... 238 1820 10
185 Bromofluorobenzene..................... 183 1985 10
------------------------------------------------------------------------
(1) Reference numbers beginning with 0, 1 or 5 indicate a pollutant
quantified by the internal standard method; reference numbers
beginning with 2 or 6 indicate a labeled compound quantified by the
internal standard method; reference numbers beginning with 3 or 7
indicate a pollutant quantified by isotope dilution.
(2) This is a minimum level at which the analytical system shall give
recognizable mass spectra (background corrected) and acceptable
calibration points. Column: 2.4m (8 ft) x 2 mm i.d. glass, packed with
one percent SP-1000 coated on 60/80 Carbopak B. Carrier gas: helium at
40 mL/min. Temperature program: 3 min at 45 °C, 8 °C per min
to 240 °C, hold at 240 °C for 15 minutes.
Note: The specifications in this table were developed from data
collected from three wastewater laboratories.




Table 3_BFB Mass-Intensity Specifications
------------------------------------------------------------------------
Mass Intensity required
------------------------------------------------------------------------
50 15 to 40 percent of mass 95.
75 30 to 60 percent of mass 95.
95 base peak, 100 percent.
96 5 to 9 percent of mass 95.
173 <2 percent of mass 174.
174 >50 percent of mass 95.
175 5 to 9 percent of mass 174
176 95 to 101 percent of mass 174
177 5 to 9 percent of mass 176.
------------------------------------------------------------------------




Table 4_Volatile Organic Compound Characteristic Masses
------------------------------------------------------------------------
Primary m/
Labeled compound Analog z's
------------------------------------------------------------------------
Acetone............................................ d6 58/64
Acrolein........................................... d2 56/58
Acrylonitrile...................................... d3 53/56
Benzene............................................ d6 78/84
Bromodichloromethane............................... 13C 83/86
Bromoform.......................................... 13C 173/176
Bromomethale....................................... d3 96/99
Carbon tetrachloride............................... 13C 47/48
Chlorobenzene...................................... d5 112/117
Chloroethane....................................... d5 64/71
2-chloroethylvinyl ether........................... d7 106/113
Chloroform......................................... 13C 85/86
Chloromethane...................................... d3 50/53
Dibromochloromethane............................... 13C 129/130
1,1-dichloroethane................................. d3 63/66
1,2-dichloroethane................................. d4 62/67
1,1-dichloroethene................................. d2 61/65
Trans-1,2-dichloroethene........................... d2 61/65
1,2-dichloropropane................................ d6 63/67
Cis-1,3-dichloropropene............................ d4 75/79
Trans-1,3-dichloropropene.......................... d4 75/79
Diethyl ether...................................... d10 74/84
p-dioxane.......................................... d8 88/96
Ethylbenzene....................................... d10 106/116
Methylene chloride................................. d2 84/88
Methyl ethyl ketone................................ d3 72/75
1,1,2,2-tetrachloroethane.......................... d2 83/84
Tetrachloroethene.................................. 13C2 166/172
Toluene............................................ d8 92/99
1,1,1-trichloroethane.............................. d3 97/102
1,1,2-trichloroethane.............................. 13C2 83/84
Trichloroethene.................................... 13C 95/133
Vinyl chloride..................................... d3 62/65
------------------------------------------------------------------------




Table 5_Acceptance Criteria for Performance Tests
----------------------------------------------------------------------------------------------------------------
Acceptance criteria at 20 µg/L
------------------------------------------------------
Initial precision and Labeled On-going
accuracy section 8.2.3 compound accuracy
Compound ----------------------------- recovery sec. 11.5
sec. 8.3 ------------
s (µg/ X (µg/L) and 14.2
L) ------------- R (µg/
P (percent) L)
----------------------------------------------------------------------------------------------------------------
Acetone.................................................. Note 1
Acrolein................................................. Note 2
Acrylonitrile............................................ Note 2
Benzene.................................................. 9.0 13.0-28.2 ns-196 4-33
Bromodichloromethane..................................... 8.2 6.5-31.5 ns-199 4-34
Bromoform................................................ 7.0 7.4-35.1 ns-214 6-36
Bromomethane............................................. 25.0 d-54.3 ns-414 d-61
Carbon tetrachloride..................................... 6.9 15.9-24.8 42-165 12-30
Chlorobenzene............................................ 8.2 14.2-29.6 ns-205 4-35
Chloroethane............................................. 14.8 2.1-46.7 ns-308 d-51
2-chloroethylvinyl ether................................. 36.0 d-69.8 ns-554 d-79
Chloroform............................................... 7.9 11.6-26.3 18-172 8-30
Chloromethane............................................ 26.0 d-55.5 ns-410 d-64
Dibromochloromethane..................................... 7.9 11.2-29.1 16-185 8-32
1,1-dichloroethane....................................... 6.7 11.4-31.4 23-191 9-33
1,2-dichloroethane....................................... 7.7 11.6-30.1 12-192 8-33
1,1-dichloroethene....................................... 11.7 d-49.8 ns-315 d-52
Trans-1,2-dichloroethene................................. 7.4 10.5-31.5 15-195 8-34
1,2-dichloropropane...................................... 19.2 d-46.8 ns-343 d-51
Cis-1,3-dichloropropene.................................. 22.1 d-51.0 ns-381 d-56
Trans-1,3-dichloropropene................................ 14.5 d-40.2 ns-284 d-44
Diethyl ether............................................ Note 1
P-dioxane................................................ Note 1
Ethyl benzene............................................ 9.6 15.6-28.5 ns-203 5-35
Methylene chloride....................................... 9.7 d-49.8 ns-316 d-50
Methyl ethyl ketone...................................... Note 1
1,1,2,2-tetrachloroethane................................ 9.6 10.7-30.0 5-199 7-34
Tetrachloroethene........................................ 6.6 15.1-28.5 31-181 11-32
Toluene.................................................. 6.3 14.5-28.7 4-193 6-33
1,1,1-trichloroethane.................................... 5.9 10.5-33.4 12-200 8-35
1,1,2-trichloroethane.................................... 7.1 11.8-29.7 21-184 9-32
Trichloroethene.......................................... 8.9 16.6-29.5 35-196 12-34
Vinyl chloride........................................... 27.9 d-58.5 ns-452 d-65
----------------------------------------------------------------------------------------------------------------
d = detected; result must be greater than zero.
ns = no specification; limit would be below detection limit.
Note 1: Specifications not available for these compounds at time of release of this method.
Note 2: Specifications not developed for these compounds; use method 603.




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Method 1625 Revision B—Semivolatile Organic Compounds by Isotope Dilution GC/MS

1. Scope and Application

1.1 This method is designed to determine the semivolatile toxic organic pollutants associated with the 1976 Consent Decree and additional compounds amenable to extraction and analysis by capillary column gas chromatography-mass spectrometry (GC/MS).

1.2 The chemical compounds listed in Tables 1 and 2 may be determined in municipal and industrial discharges by this method. The method is designed tomeet the survey requirements of Effluent Guidelines Division (EGD) and the National Pollutants Discharge Elimination System (NPDES) under 40 CFR 136.1. Any modifications of this method, beyond those expressly permitted, shall be considered as major modifications subject to application and approval of alternate test procedures under 40 CFR 136.4 and 136.5. (continued)