Comparison of Helium and Nitrogen Purge Gases for the Analysis of Volatile Organic Compounds (Vocs) by Purge and Trap

Application Note

Comparison of Helium and Nitrogen Purge Gases for the Analysis of Volatile Organic Compounds (VOCs) by Purge and Trap

Introduction Although analysis of VOCs by purge and trap (P&T) is considered a mature technique, advances in methodology and instrumentation are still being developed. Most USEPA methods for this analysis call for extraction of the analytes by purging with helium for 11 minutes at 40 ml/minute making P&T one of the largest consumers of helium in the laboratory. Many labs are seeking a less expensive alternative to helium and have turned to nitrogen as a viable option. Nitrogen is abundantly available, inert, and currently a quarter of the price of helium, resulting in significant cost savings.

This study is based on one of the most widely used methods for volatiles analysis by P&T and GC/MS; USEPA Method 8260. Suggested operating conditions for the analysis and results comparing helium to nitrogen purge are presented.

Experimental Instrumentation used for this study included an OI Analytical Eclipse 4760 Purge and Trap Sample Concentrator, an OI Analytical 4100 Water/Soil Sample Processor, and an Agilent 7890A/5975C GC/MS. Since the nitrogen molecule is larger than that of helium and has a higher heat capacity, it is able to draw more thermal energy from the purged solution. This makes it necessary to increase the thermal energy present in the purged volume. For that reason, several changes were made to the standard conditions including slowing the purge flow slightly, increasing the purge temperature, and increasing the desorb temperature.

A nine-point calibration from 1 ppb to 200 ppb was run using the conditions listed in Table 1. Acrolein and Acetonitrile were run at 2x and the ketones were run at 5x. Response factors were calculated using the internal standard approach. The same conditions were used for the helium and nitrogen purges. Initial Demonstrations of Proficiency (IDP) were run at the 50 ppb level. © 2019 Xylem© oico.com Table 1. Draw OutPlate Temperature Quadrupole Source Temperature Temperature Transfer Line Solvent Delay Scans/Second Mode Mass Spectrometer Oven Program Split Ratio Column FlowRate Inlet Liner Inlet Temperature Carrier Gas Column Gas Chromatograph Soil Lift Station Soil Oven Sample TransferSoil Rinse Water Loop-basedSettings Time LV20 Pressure Purge Gas System Gas Autosampler Six-portValve Temperature TransferLine Temperature Water Management #10 TrapOI Temperature Bake Time Desorb Time Sample Temperature Mount TemperatureSparge Purge Time Purge Gas Trap Purge-and-Trap

Operating Conditions

6 mm 200 °C 300 °C 250 °C 1.40 min 5.19 Scan 35-300amu Agilent 5975C Total GCRun is13.25 min Hold at 220°Cfor2min 40 °C/minuteto220°C 16 °C/minuteto180°C Hold at 40°Cfor1.5min 100:1 0.8 mL/min taper Agilent Ultra Inert, 1mmstraight 250 °C Zero grade helium 30 meter, 0.25mmID, 1.4 Restek Rtx-VMS Agilent 7890A 50 °C 150 °C 150 °C 80 °C Default 8.0 psi Zero grade helium/nitrogen Zero grade nitrogen Sample Processor 4100 Water/Soil #10 trap; Tenax® /SilicagelCMS P&T SampleConcentrator Eclipse 4760 140 °C 140 °C 240 °Cduringbake Ambient duringdesorb 120 °Cduringpurge 210 °Cduringbake 200 °Cduringdesorb 180 °Cduringdesorbpre-heat Ambient duringpurge 4 min 0.5 min 50 °C 50 °C 11 min Zero grade He/N

2 at 38ml/min m mdf volume 10mL *Suggested initialvolumeinvialshouldbe5mL andfinal Soil Stir DuringPurge Soil Pre-Heat/Purge Temp (˚C) Soil Pre-Heat Stir (#loops) WaterSoil Add to Vial Water Settle Time (sec) Water Stir Time (min) Rinse Water P&T Rinses (min) Desorb Time Purge(min) Time SAM D(µL) SAM C(µL) SAM B(µL) SAM A(µL) Needle Rinses Sample Type 4100 SampleProcessor Methods Waters Only 11.0 Hot 0.0 0.5 0 2 0 0 0 5 1 *1 x5mL 50 ˚C Only Soils 11.0 Hot Yes Yes 0.5 2 0 0 0 5 1 Blanks Only 11.0 Hot 0.5 2 0 0 0 5 0 2 Publication 45180419 © 2019 Xylem© oico.com Table Even withthisreduction inresponse, goodqualitydata wasachieved. limits. Please see Table 4and Table 5. When changingfrom HetoN Calibration results passedUSEPA Method8260Dcriteria. Please see Results 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Analyte 2 .

Liquid Calibration Data

1,2-dichloroethane 1,2-dichloroethane-d4 (SS) methacrylonitrile benzene 1,4-difluorobenzene (IS) 1,1-dichloropropene 2-butanone(5x) 1,1,1-trichloroethane dibromofluoromethane (SS) tetrahydrofuran carbon tetrachloride methyl acrylate chloroform bromochloromethane 2,2-dichloropropane cis-1,2-dichloroethene acrylonitrile 1,1-dichloroethane chloroprene acetonitrile(2x) methyl tert-butyl ether trans-1,2-dichloroethene acetone(5x) methylene chloride allyl chloride acrolein(2x) methyl iodide 1,1,2-trichloro-1,2,2-trifluoroethane carbon disulfide 1,1-dichloroethene ethyl ether trichlorofluoromethane chloroethane bromomethane vinyl chloride chloromethane dichlorodifluoromethane pentafluorobenzene (IS) Compound 0.866 0.449 1.271 0.438 0.264 0.448 0.327 0.4 0.675 1.086 0.569 N/A 0.59 0.054 0.506 1.274 N/A 0.681 0.086 0.825 0.568 0.441 0.831 0.996 0.995 0.31 0.484 0.542 1.112 1.179 1.112 0.108 1.035 0.496 0.069 0.481 0.25 0.042 Liquid RF Helium 2 purge, ithasbeenobservedthat response declines40-60%. Table 2 and 5.60 7.47 5.47 8.60 9.34 6.70 4.57 7.79 5.57 6.22 5.15 N/A 10.84 4.62 8.04 2.68 N/A 4.49 12.78 4.16 3.83 12.62 3.85 7.15 3.82 4.84 10.34 3.74 5.50 3.84 5.50 18.36 2.74 4.08 14.33 5.16 3.57 7.98 Table3 Helium % RSD . IDPresults were alsowellwithinmethod 1.244 0.577 1.747 0.617 0.363 0.577 0.493 0.485 0.924 1.533 0.717 N/A 0.702 0.064 0.530 1.455 N/A 0.766 0.08 1.075 0.722 0.462 1.073 0.896 1.298 0.436 0.737 0.718 1.375 1.586 1.375 0.216 1.414 0.741 0.118 0.715 0.369 0.063 Liquid RF Nitrogen 9.18 9.96 9.93 10.16 11.79 9.96 10.49 9.33 8.33 8.40 10.44 N/A 12.46 7.51 5.20 5.80 N/A 3.73 15.87 6.03 4.95 8.58 9.13 5.63 6.05 8.28 10.39 5.56 6.37 6.75 6.37 13.15 6.28 12.13 7.23 9.80 11.80 9.51 Nitrogen % RSD 3 Publication 45180419 © 2019 Xylem© oico.com Table 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 Analyte 2 .

Liquid Calibration Data (continued)

sec-butylbenzene 1,2,4-trimethylbenzene tert-butylbenzene 4-chlorotoluene trans-1,4-dichloro-2-butene 1,2,3-trichloropropane 1,3,5-trimethylbenzene 2-chlorotoluene 1,1,2,2-tetrachloroethane bromobemzene n-propylbenzene 4-bromofluorobenzene (SS) 1,4-dichlorobenzene-d4 (IS) cis-1,4-dichloro-2-butene isopropylbenzene bromoform styrene o-xylene m,p-xylenes(2x) 1,1,1,2-tetrachloroethane ethylbenzene chlorobenzene 2-hexanone(5x) 1,2-dibromoethane 1,3-dichloropropane chlorodibromomethane 1,1,2-trichloroethane ethyl methacrylate trans-1,3-dichloropropene tetrachloroethene 4-methyl-2-pentanone(5x) 2-nitropropane toluene toluene-d8(ss) chlorobenzene-d5 (IS) cis-1,3-dichloropropene 2-chloroethyl-vinyl-ether methyl methacrylate bromodichloromethane 1,2-dichloropropane dibromomethane trichloroethene Compound

0.501 0.320 0.413 0.568 0.330 0.050 0.244 0.879 1.263 N/A 0.516 0.288 0.296 0.509 0.438 0.261 0.393 3.268 2.575 2.139 2.276 0.481 0.282 2.575 2.432 1.115 0.921 3.875 0.892 N/A 0.168 1.570 0.367 0.975 0.590 1.301 0.406 1.717 1.078 0.819 0.410 0.514 Liquid RF Helium 3.85 4.19 8.44 3.84 1.65 7.39 8.36 2.57 0.86 N/A 4.16 8.68 10.09 4.73 3.34 4.49 4.34 8.06 10.54 8.33 5.33 6.74 9.37 10.54 3.79 7.19 3.96 5.05 1.76 N/A 12.81 8.73 4.57 9.28 9.32 6.57 4.00 3.79 2.56 8.96 3.76 3.56 Helium % RSD 0.555 0.327 0.363 0.617 0.367 0.058 0.250 0.956 1.400 N/A 0.453 0.186 0.212 0.556 0.455 0.294 0.432 4.388 3.313 2.674 2.215 0.340 0.305 3.313 3.053 1.323 0.948 4.490 0.857 N/A 0.103 1.879 0.347 0.878 0.690 0.655 0.579 1.740 1.086 0.583 0.382 0.482 Liquid RF Nitrogen 7.26 8.22 7.59 5.92 3.92 9.18 9.63 4.66 2.89 N/A 7.42 15.08 9.26 6.04 5.35 7.84 4.49 16.58 15.43 r=1.00 22.60 13.20 10.88 6.50 15.43 6.72 9.47 6.56 9.07 4.87 N/A 15.64 11.70 7.51 10.52 7.36 8.93 12.22 5.57 4.56 5.97 5.82 3.79 Nitrogen % RSD 4 Publication 45180419 © 2019 Xylem© oico.com Table Table 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 90 89 88 87 86 85 84 83 82 81 Analyte Analyte 3 2 . .

Solid Calibration Data Liquid Calibration Data (continued)

methyl acrylate chloroform bromochloromethane 2,2-dichloropropane cis-1,2-dichloroethene acrylonitrile 1,1-dichloroethane chloroprene acetonitrile(2x) methyl tert-butyl ether trans-1,2-dichloroethene acetone(5x) methylene chloride allyl chloride acrolein(2x) methyl iodide 1,1,2-trichloro-1,2,2-trifluoroethane carbon disulfide 1,1-dichloroethene ethyl ether trichlorofluoromethane chloroethane bromomethane vinyl chloride chloromethane dichlorodifluoromethane pentafluorobenzene (IS) 1,2,3-trichlorobenzene naphthalene 1,2,4-trichlorobenzene hexachlorobutadiene 1,2-dibromo-3-chloropropane 1,2-dichlorobenzene n-butylbenzene 1,4-dichlorobenzene 1,3-dichlorobenzene p-isopropytoluene Compound Compound

N/A 0.826 2.771 0.867 0.459 0.255 1.563 2.629 1.697 1.658 2.629 0.707 1.050 0.352 0.567 0.579 1.109 1.228 1.109 0.103 1.068 0.516 0.061 0.533 0.260 0.044 0.926 0.482 1.389 0.447 0.260 0.481 0.329 0.412 0.703 1.117 0.635 Liquid RF Solid RF Helium Helium N/A 9.16 14.3 9.23 7.92 6.20 2.42 7.81 2.55 3.66 11.87 12.00 6.60 10.01 16.13 8.54 10.13 6.65 10.13 11.50 8.52 6.45 6.94 6.41 12.50 10.92 9.90 13.94 10.50 11.25 4.79 13.67 10.61 10.68 14.46 9.70 9.53 Helium Helium % RSD % RSD N/A 1.531 4.679 1.422 0.613 0.377 1.947 3.211 1.695 1.734 3.423 0.575 1.266 0.395 0.823 0.698 1.281 1.502 1.281 0.141 1.332 0.692 0.074 0.722 0.346 0.052 1.266 0.621 1.837 0.621 0.300 0.621 0.488 0.505 0.906 1.529 0.785 Liquid RF Nitrogen Nitrogen Solid RF N/A 5.79 7.30 8.48 5.63 15.1 6.69 10.8 3.83 4.87 18.93 14.79 5.95 4.82 6.55 4.96 7.16 4.61 7.16 9.21 5.78 9.04 12.94 4.79 6.72 10.52 4.70 7.78 7.18 8.05 4.44 7.78 9.73 7.34 8.23 9.55 6.94 Nitrogen Nitrogen % RSD % RSD 5 Publication 45180419 © 2019 Xylem© oico.com Table 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 Analyte 3 .

Solid Calibration Data (continued)

4-bromofluorobenzene (SS) 1,4-dichlorobenzene-d4 (IS) cis-1,4-dichloro-2-butene isopropylbenzene bromoform styrene o-xylene m,p-xylenes(2x) 1,1,1,2-tetrachloroethane ethylbenzene chlorobenzene 2-hexanone(5x) 1,2-dibromoethane 1,3-dichloropropane chlorodibromomethane 1,1,2-trichloroethane ethyl methacrylate trans-1,3-dichloropropene tetrachloroethene 4-methyl-2-pentanone(5x) 2-nitropropane toluene toluene-d8(ss) chlorobenzene-d5 (IS) cis-1,3-dichloropropene 2-chloroethyl-vinyl-ether methyl methacrylate bromodichloromethane 1,2-dichloropropane dibromomethane trichloroethene 1,2-dichloroethane 1,2-dichloroethane-d4 (SS) methacrylonitrile benzene 1,4-difluorobenzene (IS) 1,1-dichloropropene 2-butanone(5x) 1,1,1-trichloroethane dibromofluoromethane (SS) tetrahydrofuran carbon tetrachloride Compound

0.207 0.203 0.504 0.442 0.247 0.370 0.563 0.053 0.343 1.221 N/A 0.698 0.055 0.860 0.657 0.287 0.878 0.883 N/A 0.115 1.451 0.293 0.910 0.559 0.600 0.409 1.577 1.032 0.411 0.331 0.447 0.467 0.282 0.324 0.548 0.314 0.029 0.153 0.823 1.244 N/A 0.511 Solid RF Helium 14.52 13.07 6.91 6.35 5.64 5.48 8.27 3.93 6.96 6.33 N/A 8.79 9.00 7.20 2.17 9.06 7.48 1.92 N/A 13.47 11.05 6.75 11.37 9.87 9.36 6.33 8.30 7.56 11.98 7.69 5.36 7.33 5.19 10.71 5.82 8.74 11.84 13.03 6.57 1.47 N/A 5.91 Helium % RSD 0.132 0.155 0.513 0.434 0.251 0.392 0.596 0.056 0.327 1.371 N/A 0.732 0.052 1.057 0.743 0.284 1.058 0.886 N/A 0.083 1.703 0.285 0.811 0.641 0.587 0.540 1.572 1.005 0.323 0.316 0.416 0.484 0.282 0.263 0.566 0.348 0.033 0.156 0.900 1.405 N/A 0.427 Nitrogen Solid RF 20.71 10.28 2.93 3.81 4.52 5.14 6.47 6.98 8.52 4.83 N/A 7.14 10.06 5.55 4.28 15.46 5.90 3.95 N/A 14.93 11.29 9.03 13.58 9.15 11.22 8.45 8.00 5.27 10.45 6.11 5.69 3.82 6.46 18.86 5.77 6.23 8.48 13.56 4.97 3.04 N/A 9.25 r=0.997 Nitrogen % RSD 6 Publication 45180419 © 2019 Xylem© oico.com Table Table 15 14 13 12 11 10 9 8 7 6 5 4 3 2 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 Analyte Analyte 4 3 . .

Liquid IDPs Solid Calibration Data (continued)

methylene chloride allyl chloride acrolein methyl iodide 1,1,2-trichloro-1,2,2-trifluoroethane carbon disulfide 1,1-dichloroethene ethyl ether trichlorofluoromethane chloroethane bromomethane vinyl chloride chloromethane dichlorodifluoromethane 1,2,3-trichlorobenzene naphthalene 1,2,4-trichlorobenzene hexachlorobutadiene 1,2-Dibromo-3-chloropropane 1,2-dichlorobenzene n-butylbenzene 1,4-dichlorobenzene 1,3-dichlorobenzene p-isopropytoluene sec-butylbenzene 1,2,4-trimethylbenzene tert-butylbenzene 4-chlorotoluene trans-1,4-dichloro-2-butene 1,2,3-trichloropropane 1,3,5-trimethylbenzene 2-chlorotoluene 1,1,2,2-tetrachloroethane bromobenzene n-propylbenzene

Compound Compound

0.150 1.549 2.630 1.659 1.631 2.621 3.249 2.497 2.084 2.175 0.328 0.202 2.497 2.346 0.818 0.909 3.670 0.897 2.127 0.930 0.537 Recovery Liquid % Solid RF Helium Helium 100.29 100.29 100.76 93.47 97.65 95.21 98.62 98.61 96.47 95.54 96.88 98.00 96.67 91.69 10.30 5.23 7.86 8.17 5.04 9.90 7.84 12.06 10.21 7.31 6.71 8.53 12.06 7.26 10.01 6.87 7.61 9.11 15.81 7.36 14.23 Helium Helium % RSD % RSD 4.30 2.07 8.00 3.43 5.00 3.33 3.31 2.85 4.99 3.64 2.02 3.05 3.56 5.01 0.213 1.790 3.154 1.607 1.673 3.368 4.363 3.161 2.641 2.169 0.258 0.212 3.161 2.867 1.022 0.944 4.090 1.583 3.593 1.434 0.800 Recovery Liquid % Nitrogen Nitrogen Solid RF 100.49 97.73 94.40 99.18 91.28 95.84 95.60 95.95 91.28 94.52 96.63 98.01 96.12 86.44 15.64 5.09 6.12 5.65 4.21 16.29 12.98 14.13 19.66 11.41 10.52 9.16 14.13 8.87 8.01 7.57 11.50 9.90 5.91 9.45 13.49 Nitrogen Nitrogen % RSD % RSD 2.75 2.20 4.14 2.16 4.46 3.05 4.14 1.64 4.46 2.32 0.48 1.77 1.50 3.99 7 Publication 45180419 © 2019 Xylem© oico.com Table 55 54 53 52 51 50 49 48 47 45 44 43 42 41 40 39 38 37 36 35 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 Analyte 4 .

Liquid IDPs (continued)

chlorodibromomethane 1,1,2-trichloroethane ethyl methacrylate trans-1,3-dichloropropene tetrachloroethene 4-methyl-2-pentanone 2-nitropropane toluene toluene-d8(ss) cis-1,3-dichloropropene 2-chloroethyl-vinyl-ether methyl methacrylate 1,2-dichloropropane bromodichloromethane dibromomethane trichloroethene 1,2-dichloroethane 1,2-dichloroethane-d4 (SS) methacrylonitrile benzene 1,1-dichloropropene 2-butanone 1,1,1-trichloroethane dibromofluoromethane (SS) tetrahydrofuran carbon tetrachloride methyl acrylate chloroform bromochloromethane 2,2-dichloropropane cis-1,2-dichloroethene acrylonitrile 1,1-dichloroethane chloroprene acetonitrile methyl tert-butyl ether trans-1,2-dichloroethene acetone Compound

Recovery Liquid % Helium 103.66 103.16 100.04 101.63 101.15 107.33 102.25 101.18 103.50 100.99 100.83 101.43 105.62 104.39 101.33 100.69 101.02 102.85 96.47 87.39 98.15 99.52 97.92 97.30 92.85 99.12 98.97 77.01 99.91 98.93 96.14 98.88 98.55 94.24 98.88 97.60 93.34 99.56 Helium % RSD 2.90 9.07 3.71 1.64 3.23 3.99 6.09 2.80 2.97 2.59 3.01 5.87 2.41 2.41 8.39 1.32 1.87 2.53 2.42 2.43 2.02 2.56 2.06 1.17 2.10 3.18 2.43 1.48 2.05 1.42 2.15 1.91 4.50 1.15 2.33 2.80 4.44 3.25 Recovery Liquid % Nitrogen 100.00 101.56 101.81 103.87 103.87 100.65 101.88 100.37 102.57 107.87 101.07 109.23 103.38 100.40 101.17 104.13 101.13 100.12 101.74 101.01 102.09 96.24 96.08 99.45 97.21 91.41 99.43 94.12 93.89 99.25 98.87 99.71 98.98 98.53 95.31 98.46 99.71 98.98 Nitrogen % RSD 1.79 8.61 3.47 1.67 1.71 1.57 3.12 1.57 2.30 1.55 2.30 5.46 1.25 2.58 2.12 0.74 0.44 1.53 2.04 2.90 2.46 1.51 1.78 0.56 1.77 2.85 0.72 0.97 0.89 1.66 2.35 0.81 1.87 1.24 1.07 2.66 2.43 2.18 8 Publication 45180419 © 2019 Xylem© oico.com Table 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 67 66 65 64 63 62 61 60 59 58 57 56 Analyte 4 .

Liquid IDPs (continued)

1,2,3-trichlorobenzene naphthalene 1,2,4-trichlorobenzene hexachlorobutadiene 1,2-Dibromo-3-chloropropane 1,2-dichlorobenzene n-butylbenzene 1,4-dichlorobenzene 1,3-dichlorobenzene p-isopropytoluene sec-butylbenzene 1,2,4-trimethylbenzene tert-butylbenzene 4-chlorotoluene trans-1,4-dichloro-2-butene 1,2,3-trichloropropane 1,3,5-trimethylbenzene 2-chlorotoluene 1,1,2,2-tetrachloroethane n-propylbenzene bromobenzene 4-bromofluorobenzene (SS) cis-1,4-dichloro-2-butene isopropylbenzene bromoform styrene o-xylene m,p-xylenes 1,1,1,2-tetrachloroethane ethylbenzene chlorobenzene 2-hexanone 1,2-dibromoethane 1,3-dichloropropane Compound

Recovery Liquid % Helium 100.83 103.98 102.52 105.69 101.22 106.88 105.16 104.88 102.87 100.52 102.97 101.04 101.64 100.53 103.18 100.08 100.10 104.10 100.42 101.79 108.94 106.97 108.49 107.72 105.54 103.01 108.49 103.81 93.48 97.65 96.86 98.06 98.40 97.38 Helium % RSD 1.89 1.01 1.30 3.72 2.45 2.44 1.61 1.34 2.05 1.74 1.25 1.68 3.92 0.59 2.20 3.66 2.43 2.26 2.61 2.77 1.45 2.24 1.06 1.08 2.01 1.82 1.59 2.17 1.15 3.69 2.78 1.59 1.35 0.57 Recovery Liquid % Nitrogen 101.96 106.44 102.64 108.05 100.94 109.95 108.74 107.67 105.17 106.74 100.35 101.74 101.50 106.62 100.23 107.89 100.81 113.98 111.26 113.92 108.24 101.88 113.92 104.61 100.52 97.55 98.62 99.97 98.22 98.40 95.85 99.67 94.53 97.49 Nitrogen % RSD 1.84 1.57 2.14 6.55 8.89 1.24 0.65 1.33 1.25 2.31 0.64 1.28 1.22 1.11 0.89 2.69 2.47 2.05 0.98 4.44 1.06 0.49 0.49 2.20 1.63 1.82 1.59 1.99 0.70 3.20 1.64 1.59 1.06 0.67 9 Publication 45180419 © 2019 Xylem© oico.com Table 45 44 43 42 41 40 39 38 37 36 35 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 Analyte 5 .

Solid IDPs

bromodichloromethane dibromomethane trichloroethene 1,2-dichloroethane 1,2-dichloroethane-d4 (SS) methacrylonitrile benzene 1,1-dichloropropene 2-butanone 1,1,1-trichloroethane dibromofluoromethane (SS) tetrahydrofuran carbon tetrachloride methyl acrylate chloroform bromochloromethane 2,2-dichloropropane cis-1,2-dichloroethene acrylonitrile 1,1-dichloroethane chloroprene acetonitrile methyl tert-butyl ether trans-1,2-dichloroethene acetone methylene chloride allyl chloride acrolein methyl iodide 1,1,2-trichloro-1,2,2-trifluoroethane carbon disulfide 1,1-dichloroethene ethyl ether trichlorofluoromethane chloroethane bromomethane vinyl chloride chloromethane dichlorodifluoromethane cis-1,3-dichloropropene 2-chloroethyl-vinyl-ether methyl methacrylate 1,2-dichloropropane

Compound Recovery Solid % Helium 100.96 93.94 92.39 91.53 96.05 89.52 92.32 92.95 92.60 94.27 93.78 93.09 92.44 90.71 91.81 91.54 92.46 96.33 99.73 95.01 94.11 91.70 95.57 89.76 97.18 94.82 96.02 99.06 98.15 95.00 96.65 92.12 93.61 97.93 94.49 88.46 95.51 94.05 99.18 93.95 99.18 93.69 94.54 Helium % RSD 2.53 2.34 3.34 2.94 6.96 2.15 4.35 3.22 2.51 2.82 4.34 2.90 2.89 3.45 2.85 5.28 2.40 2.86 3.74 6.38 2.41 5.28 0.79 2.75 1.53 3.38 2.72 2.62 2.28 2.82 0.25 5.04 3.56 3.35 2.02 2.65 5.46 2.55 2.26 1.87 2.26 4.92 3.74 Recovery Nitrogen Solid % 87.17 87.89 93.85 88.54 92.44 93.66 88.00 90.42 88.75 92.60 88.00 87.43 91.10 88.90 87.08 87.83 93.89 77.47 93.48 93.24 92.78 92.46 91.37 90.91 97.58 98.34 90.22 92.60 90.69 91.38 98.01 91.64 89.21 98.42 90.99 94.03 89.99 91.80 91.94 90.54 91.94 97.77 94.64 Nitrogen % RSD 3.45 6.63 3.51 2.18 8.40 3.82 2.89 4.19 3.68 2.87 2.89 3.71 3.79 1.68 2.67 4.20 1.09 2.40 2.24 0.79 1.40 2.16 2.26 1.12 3.45 0.59 1.40 2.18 2.33 3.45 2.78 2.80 2.54 2.53 1.92 1.82 3.12 2.90 1.46 2.52 1.46 7.51 3.12 10

Solid IDPs (continued)

Recovery Solid % Helium 102.74 102.44 101.27 100.71 102.18 104.49 102.73 105.09 101.89 100.66 105.09 101.46 102.01 104.88 103.02 101.46 90.81 99.31 94.60 97.80 97.04 94.24 95.13 97.52 95.86 99.83 87.67 95.73 95.10 99.28 97.45 93.46 92.88 95.33 95.00 96.84 97.45 89.77 99.39 94.62 93.71 94.51 95.63 Helium % RSD 2.38 1.79 1.94 2.34 2.13 2.72 2.84 2.45 3.31 1.95 2.52 2.14 2.83 3.06 2.25 0.97 3.46 4.33 2.29 2.03 4.24 2.07 3.16 1.21 2.08 2.86 3.27 2.71 2.35 1.65 2.61 2.11 2.71 2.01 3.06 2.29 2.25 1.96 5.61 2.59 1.72 1.69 1.75 Recovery Nitrogen Solid % 102.12 100.89 100.69 100.85 102.81 102.07 102.81 103.93 100.34 97.66 92.75 93.59 91.21 97.63 92.39 93.60 93.31 93.40 92.90 87.59 90.71 91.06 98.29 92.04 96.29 88.35 86.02 92.67 94.19 93.28 89.73 91.13 94.92 88.71 97.99 97.50 92.83 91.50 97.64 82.66 90.74 97.30 97.31 Nitrogen % RSD 1.21 2.07 0.84 0.88 1.31 1.79 1.71 0.25 1.89 0.98 1.20 1.41 1.69 2.05 1.66 5.47 2.23 2.76 1.89 2.22 4.36 1.62 1.30 0.70 1.66 2.13 1.99 2.41 3.14 1.91 1.27 3.93 2.41 2.82 3.76 2.46 2.07 1.73 7.98 1.79 1.38 1.41 0.91 11

Liquid withHePurge Solid withHePurge

Liquid withN Solid withN 2 Purge 2 Purge

Publication 45180419 Conclusions

Nitrogen is a viable alternative purge gas for the analysis of volatile compounds by USEPA Method 8260D which may result in cost savings for the laboratory. It has been observed, however, that using nitrogen as a purge gas may result in more frequent source cleaning and calibrations to be performed.

References

Volatile Organic Compounds by Gas Chromatography/Mass Spectrometry. USEPA Office of Solid Waste, SW 846, Method 8260D, Rev 4, February 2017.

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