High‐speed capillary column GC for rapid screening of gasoline to diesel range organic compounds

Abstract

A high-speed gas chromatography (GC) instrument has been developed for near real-time screening of soil gas samples continuously generated from a cone penetrometer (CPT) equipped with a heated probe tip. The GC instrument uses a cryofocusing inlet system which can preconcentrate gasoline and diesel vapor and introduce a very narrow vapor plug into the capillary separation column. The GC instrument can be operated either in a high-speed screening mode or in a higher resolution advanced field analysis mode. In the high speed mode, a short capillary separation column is used with a photolonization detector to selectively detect aromatic (BTEX) compounds in petroleum fuel spills in a time frame of 10–20 s and with detection limits in the ppb range. In the advanced field mode, a longer column and flame ionization detector are used to obtain a finger-print chromatogram which is useful in determination of fuel type. In this mode, analysis times are typically about 200 s. The high-speed GC instrument is designed to be located in the CPT truck and connected directly to a heated gas transport line. In the high-speed screening mode, continuous sampling and near real-time analysis provide very high spatial resolution as well as high speed for site characterization. © 1996 John Wiley & Sons, Inc. Field Analyt Chem Technol 1: 97–102, 1996.