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2 Trace Analybix Laboratory,Inn. TOTAL PETROLEUM HYDROCARBONS AS GASOLINE (TPH-G) WITH BENZENE, TOLUENE, XYLENE, AND ETHYLBENZENE (BTXE) FOR AIR Met od: This method is based on California Department of Health Services Method for ' Total Petroleum Hydrocarbons as Gasoline and BTXE. This method uses alternative sample introduction and gas chromatographic conditions as specified below. Sample Pea ation: There is no sample preparation. ' Sample Introduction: Air samples are introduced to the gas chromatograph (GC) through a purge and trap device. A gas tight syringe is used to draw a sample from the Tedlar bag or sample ' canister. The sample is slowly injected into the purge and trap, and is adsorbed onto the trap. The trap is then heated, and the sample is thermally desorbed into the GC column. ' Gas Chromatography Analysis: The volatile organics are separated on a 6-ft x 2 mm I.D. gas chromatography column packed with 5% SP-1200/1 .75% Bentone-34 on Supelcoport. A flame ionization detector (FID) is used to detect total petroleum hydrocarbons as gasoline (TPH-G) . The FID is preceded by a photoionization detector (PID) , which is used to detect the BTXE. Gs Chr matograph Conditions: ' CARRIER GAS: Nitrogen FLOW RATE: 30 ml/min. INJECTOR TEMPERATURE: 240° C DETECTOR TEMPERATURE: 2700 C ' INITIAL TEMPERATURE: 540 C Hold for 2 minutes PROGRAM RATE: 60 C/min. ' FINAL TEMPERATURE: 9oo C Hold for 17 minutes Calculation: TPH-G is quantified by comparing the sum of the area of peaks from the sample to the sum of the area of peaks in the gasoline standard. The BTXE are identified by comparing the retention times of the sample peaks to those of the standards. The compounds are quantified by comparing the area of the sample peaks to those of the standards. 9/7/90 I