A fast thermal desorption unit for micro thermal desorption tubes, Part II: Method development and validation for explosives and chemical warfare agent simulants

A thermal desorption FF-TG-GC/MS method with a cycle time of just 164 s including cryofocusing, thermal desorption, analyte separation and system cool down was developed for the analysis of ten explosives and six chemical warfare agent (CWA) simulants. Sampling was carried out both in liquid and gaseous form using micro thermal desorption tubes ($\mu$TD-tubes, 1.4 mm I.D., 10 mg Tenax TA). In addition to the desorption conditions, the effects of deactivated $\mu$TD-tubes, the spatial temperature gradient along the separation column and additional cryofocusing to refocus the analytes were evaluated. Limits of detection between 0.17 and 9.18 ng/$\mu$L and R${}^2$ values $\ge$  0.983 for calibration curves (with the exception of PETN) were obtained. Relative standard deviations of mainly $<$15% were achieved for within day repeatability. The fluctuations in the peak areas were mostly below 20% with between-day repeatability measured across three days.