Fast GC instrumentation and analysis for field applications

Abstract

Environmental contaminants are found in a wide variety of molecular shapes and sizes, with organic pollutants exhibiting vapor pressures in the 10³–10⁻⁶ torr range. This translates into a need for chemical analyzers that are capable of analyzing both volatile compounds (i.e., those compounds that have high vapor pressures at ambient temperatures) as well as semivolatile substances (i.e., those compounds that must be heated before they exhibit substantial vapor pressures). Volatile environmental analytes are found in gaseous, liquid, or solid sample matrices, whereas semivolatile analytes exist as either liquids or solids, including aerosol dispersions. Unfortunately, conventional field-portable GC analyzers are only capable of analyzing for volatile analytes. A small, fast, dual-high-resolution-column GC instrument that is capable of analyzing both volatile and semivolatile analytes has been developed and patented. As typically configured, it uses two narrow-bore, 100-micron ID separation columns, is temperature programmable at rates of 5–20 °C per second, and uses less than 150 W of dc power. Typical separation times for compounds with Kovatt's retention indices of <1000 are 10–15 s, and compounds with retention indices of up to 2500 are separated in <1min. Because the instrument has dual columns and detectors, analytes are simultaneously analyzed on columns with different liquid phases, thus providing added confidence in the quality of the analytical data. Because this fieldable GC device uses a solid-sorbent trapping system with a conventional heated injector inlet system, it can analyze a wide variety of sample matrices, including gases, dilute gases, thermal extracts from VOS tubes, purge-and-trap water/soil extracts, headspace samples, membrane extracts, SPME, thermal and SCF extracts, liquid organic solvent extracts, and direct aqueous samples. This report describes this new instrument and presents typical data from analysis of volatile and semivolatile analytes in a variety of sample matrices. © 2001 John Wiley & Sons, Inc. Field Analyt Chem Technol 5: 97–105, 2001