Optimized analysis of gasoline (BTEX) in water and soil using GC/FID with purge and trap
This document describes an optimized method for determining gasoline components, specifically gasoline range organics (GROs) and benzene, toluene, ethylbenzene, and xylenes (BTEX), in contaminated water and soil. The method utilizes modified EPA Methods 8015/8020 with capillary gas chromatography (GC) and a flame ionization detector (FID) or photoionization detector (PID). The analysis employs an Agilent 7695A Purge and Trap (P and T) system coupled with an Agilent 5890 Series II gas chromatograph.
| Gas chromatograph | 5890 Series II |
|---|---|
| Column | HP-1, 30 m x 0.53 mm x 5.0 µm |
| Detector | FID |
| Purge time | 11 min |
| Dry purge time | 1 min |
| Desorb time | 2 min |
| Bake time | 5 min |
The optimal sample purge time is 11 minutes, or 440 ml of helium purge gas, to ensure efficient recovery of high-boiling fractions.
The optimized GC run time achieved is 17 minutes using a thin-film HP-1 column and faster oven temperature programs.