Optimizing the Analysis of Volatile Organic Compounds

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60 www.restekcorp.com Conclusion Analyses of volatile organic compounds – VOCs – generally require concentration of the sample using dynamic headspace (purge and trap), which reduces matrix effects and increases sensitivity, relative to other extraction techniques. The concentrated sample is transferred to the capillary GC column. Because GC detectors operate well with higher flows (10mL/min.), wide-bore columns, 0.45mm ID to 0.53mm ID, are appropriate. GC/MS instruments have the greatest sensitivity, but flow into the MS source cannot exceed 1mL/min. This makes narrow-bore columns, usually 0.18mm ID to 0.25mm ID, but up to 0.32mm ID, the preferred choice for GC/MS analysis. The column is plumbed through the injection port to allow high desorb flows (>10mL/min.) and sample splitting at the injection port (>10:1). Determining the type of stationary phase in the capillary column is a matter of preference and requires an examination of conditions specific to the analysis to be performed. Information in this guide explains many of the factors to be considered in analyses of VOCs, but cannot anticipate every situation. If you have any questions regarding this guide, or your particular application, please contact our Technical Service Team via email at support@restekcorp.com or via phone at 800-356-1688 or 814-353-1300, ext. 4. Recommended Products Columns Rtx ® -502.2 Columns...............................................................................................................61 Rtx ® -Volatiles Columns..........................................................................................................61 Rtx ® -624 Columns..................................................................................................................61 Rtx ® -VMS Columns...............................................................................................................61 Rtx ® -VGC Columns ...............................................................................................................62 Rtx ® -VRX Columns ...............................................................................................................62 Rtx ® -1 Columns......................................................................................................................62 Guard Columns & Transfer Lines ...................................................................................62, 63 Accessories Connectors .......................................................................................................................20, 64 Direct Injection Liner, Vu-Tight ® ...........................................................................................18 ELCD Reaction Tubes ...........................................................................................................29 ELCD Transfer Lines.............................................................................................................27 FID Jets ..................................................................................................................................25 Gas Leak Detector ...........................................................................................................36, 65 Gas Pressure Regulator ..........................................................................................................28 Inlet Liners for Volatiles Analysis..........................................................................................65 Low-Volume Injectors......................................................................................................19, 63 Moisture Control Bypass Line...............................................................................................14 MSD Source Nut....................................................................................................................35 PID Lamps .............................................................................................................................24 Sample Vials...........................................................................................................................65 Spargers, Purge and Trap .........................................................................................................9 Syringes for Purge and Trap ..................................................................................................64 Analytical Reference Materials 502.2 Mixes & Kits................................................................................................................68 601 & 602 Mixes & Kits .......................................................................................................68 624 Mixes & Kits.............................................................................................................67, 68 8260 Mixes & Kits...........................................................................................................66, 67 CLP VOC Mixes & Kits...................................................................................................68-70 PVOC/GRO/BTEX Mixes .....................................................................................................67 Note: Many additional reference materials, including custom mixes, are available from Restek. Please call us at 800-356-1688, or contact your Restek distributor; we’ll help you find what you’re looking for.
Ordering Information | Rtx ® Rtx -VMS (Fused Silica) ® -VMS Special polymer formulation designed specifically for volatiles analysis by GC/MS. Complete separation of all US EPA Method 8260 compounds in less than 18 minutes. Excellent thermal stability resulting in low bleed. Wide variety of column dimensions. ID df (µm) temp. limits 30-Meter 60-Meter 75-Meter 0.25mm 1.40 -40 to 240/260°C 19915 19916 0.45mm 2.55 -40 to 240/260°C 19908 19909 0.53mm 3.00 -40 to 240/260°C 19985 19988 19974 ID df (µm) temp. limits 20-Meter 40-Meter 0.18mm 1.00 -40 to 240/260°C 49914 49915 Rtx ® -VGC Special polymer formulation designed for volatiles analysis using PID/ELCD. Performs US EPA Method 8021A analysis in less than 28 minutes. Excellent separation of the trihalomethanes. Excellent inertness and thermally stable to 260°C. Ordering Information | Rtx ® -VGC (Fused Silica) ID df (µm) temp. limits 30-Meter** 60-Meter** 75-Meter 105-Meter 0.25mm 1.40 -40 to 240/260°C 19415 19416 0.45mm 2.55 -40 to 240/260°C 19408 19409 0.53mm 3.00 -40 to 240/260°C 19485 19488 19474 19489 ID df (µm) temp. limits 20-Meter 40-Meter 0.18mm 1.00 -40 to 240/260°C 49414 49415 Ordering Information | Rtx ® Rtx -VRX (Fused Silica) ® -VRX Excellent selectivity for volatile compound analysis. Equivalent performance to DB-VRX column. Excellent for US EPA Method 8021 analyses. ID df (µm) temp. limits 30-Meter** 60-Meter** 75-Meter 105-Meter 0.25mm 1.40 -40 to 240/260°C 19315 19316 0.45mm 2.55 -40 to 240/260°C 19308 19309 0.53mm 3.00 -40 to 240/260°C 19385 19388 19374 19389 ID df (µm) temp. limits 20-Meter 40-Meter 0.18mm 1.00 -40 to 240/260°C 49314 49315 Rtx ® -624 Recommended for analyses of volatile organic compounds (VOCs) in EPA Methods. Crossbond ® technology. 280°C thermal stability. Similar to DB-624 and HP-624 columns. Ordering Information | Rtx ® -624 (Fused Silica) (Crossbond ® 6% cyanopropylphenyl/94% dimethyl polysiloxane) ID df (µm) temp. limits 30-Meter 60-Meter 75-Meter 105-Meter 0.25mm 1.40 -20 to 240°C 10968 10969 0.45mm 2.55 -20 to 240°C 10982 0.53mm 3.00 -20 to 240°C 10971 10973 10974 10975 ID df (µm) temp. limits 10-Meter 20-Meter 40-Meter 0.18mm 1.00 -20 to 240°C 40924 40925 61 www.restekcorp.com
Page 1 and 2:
Optimizing the Analysis of Volatile
Page 3 and 4:
EPA Method Definitions Many EPA met
Page 5 and 6:
Table I. State gasoline methods inc
Page 7 and 8:
Purge and Trap Theory Concentration
Page 9 and 10: Step 5. Desorb Once the desorb preh
Page 11 and 12: Adsorbent Materials Tenax ® Adsorb
Page 13 and 14: Table II. Compositions and characte
Page 15 and 16: Troubleshooting Common Problems Ass
Page 17 and 18: Broad Peaks: Peak broadening is ano
Page 19 and 20: Figure 14. Configuring your GC is s
Page 21 and 22: Narrow-bore Systems (0.18mm ID - 0.
Page 23 and 24: Detection Systems VOCs can be analy
Page 25 and 26: FID Operation The flame ionization
Page 27 and 28: Figure 22. Cross-section of the The
Page 29 and 30: Similarly, the PTFE transfer line b
Page 31 and 32: Figure 29. Electromagnetic fields f
Page 33 and 34: Abundance 320000 280000 240000 2000
Page 35 and 36: Connect the capillary column, 0.25m
Page 37 and 38: Applications Using GC Detection Sys
Page 39 and 40: Figure 39B. An Rtx ® -VGC primary
Page 41 and 42: Rtx ® -502.2 75m, 0.45mm ID, 2.55
Page 43 and 44: Figure 41B. Analytes listed in EPA
Page 45 and 46: Figure 42B. An Rtx ® -VGC / Rtx ®
Page 47 and 48: Purge and Trap Applications Using P
Page 49 and 50: Gasoline Analysis with Oxygenates a
Page 51 and 52: Figure 47. Volatile organics by US
Page 53 and 54: 1. dichlorodifluoromethane 2. chlor
Page 55 and 56: 1. chloromethane 2. vinyl chloride
Page 57 and 58: Table IX Volatile organic compounds
Page 59: Table XI. Choosing a Volatiles GC C
Page 63 and 64: Siltek -Deactivated Guard Columns/
Page 65 and 66: Leak Detective II Leak Detector Af
Page 67 and 68: Method 8260 8260 Internal Standard
Page 69 and 70: 8021/502.2 Surrogate Mix #1 1-bromo
Page 71 and 72: 04.2 & 04.1 SOW CLP 04.1 VOA CAL200
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