Development and evaluation of a low thermal mass gas chromatograph for rapid forensic GC–MS analyses

Abstract

Field as well as laboratory gas chromatography–mass spectrometry (GC–MS) systems are limited in several ways. Laboratory systems with air circulation ovens are bulky, power inefficient, and have a narrow range of temperature programming rates. Commercial field-portable GC–MS systems are too heavy, and many are limited to isothermal column temperature control. A resistively heated low thermal mass (LTM) GC system has been developed that can overcome most of these limitations, offering laboratory-level performance, or better, in a small, lightweight package. A prototype LTM GC was developed and evaluated in parallel with a commercial laboratory GC–MS used as a benchmark. A series of hydrocarbons, a Grob mixture, and a drug mixture critical pair of cocaine and nortriptyline were analyzed under different chromatographic conditions, and the performance of both systems was compared in terms of speed, efficiency, temperature control, resolution, precision, and power demand. The LTM GC was found to provide performance that was equivalent to the lab-based commercial GC when conventional temperature ramp rates were used (up to 30°C/min). The LTM GC provided additional advantages over the conventional GC system in terms of positive or negative temperature ramping rates and range, cool-down time reduction, and lower power requirements (1–5 W/m). This new GC system demonstrated a capability for a wider range of linear temperature programming rates providing analysts flexibility when performing established forensic methods. Method development and implementation of the LTM GC was successful in demonstrating GC analyses that are controllable, reproducible, and fieldable. © 2002 Wiley Periodicals, Inc.* Field Analyt Chem Technol 5: 288–301, 2001; DOI 10.1002/fact.10011