Hybrid preconcentrator/focuser module for determinations of explosive marker compounds with a micro-scale gas chromatograph

作者：Serrano Gustavo; Sukaew Thiti****; Zellers Edward T^*

来源：Journal of Chromatography A, 2013, 1279: 76-85.

DOI：10.1016/j.chroma.2013.01.009

• Preconcentration
• Explosives
• Microfabrication
• Gas chromatography

This article describes the development and characterization of a partially selective preconcentrator/focuser (PCF) module for a field-portable micro-scale gas chromatograph (mu GC) designed to rapidly determine trace levels of two vapor-phase markers of the explosive trinitrotoluene (TNT): 2,3-dimethy1-2,3-dinitrobutane (DMNB) and 2,4-dinitrotoluene (2,4-DNT). The PCF module has three primary components. The first is a high-volume sampler, comprising a resistively-heated 6-cm long stainless steel tube packed with tandem beds of the graphitized carbons Carbopack B (C-B, 30 mg) and Carbopack Y (C-Y, 15 mg), which traps the markers but permits more volatile interferences to pass through largely unretained. The second component is a microfocuser (mu F), comprising a 4.2 x 9.8 mm Si chip containing a deep-reactive-ion-etched (DRIE) cavity packed with 2 mg of C-B, a Pyrex cap, integrated heaters, and etched fluidic channels. The third component is a commercial polymer-membrane filter used as a pre-trap to remove particles and adsorbed low volatility interferences. Markers captured in the sampler are thermally desorbed and transferred to the mu F, and then thermally desorbed/injected from the mu F into a downstream separation (micro)column and detected. Scrubbed ambient air is used as carrier gas. The adsorbent capacities, baseline temperatures, sampling and desorption flow rates, and heating profiles were optimized for each PCF module component while minimizing the analysis time. An overall transfer efficiency of 86% was achieved at marker concentrations of similar to 0.2-2.6 ppb. In the final configuration the PCF module requires just 60 s to collect a 1-L sample (3 L/min), focus (40 mL/min), and inject the markers (3 mL/min), producing half-maximum injection peak widths of similar to 2 and 5 s, and preconcentration factors of 4500 and 1800, for DMNB and 2,4-DNT, respectively.

• 出版日期2013-3-1