Hyperfast Flow-Field Thermal Gradient GC/MS of Explosives with Reduced Elution Temperatures.

Hyperfast GC/MS below 60 s of measurement time has been used for the measurement of explosives. The new flow-field thermal gradient GC (FF-TG-GC) utilizes a modified transport process of the explosives at lowered temperatures. In combination with the focusing effect of the gradient, high-resolution chromatograms are obtained even in very short time intervals. The reduction of the elution temperature by applying a thermal gradient along the chromatographic column is demonstrated by the simulation of the migration of analytes through the column. The simulation shows an interesting effect of the difference between maximum temperature and elution temperature of analytes during their separation with the spatial gradient. The results show the benefit of the gradient elution both from a modeling perspective and by measurements of explosives with low limits of detection (LOD) in the range from 0.1 to 20 μg/mL (0.5 to 150 pg of analyte mass on column). Results were compared to state-of-the-art vacuum outlet GC/MS as a reference method. A correlation between the reduction of elution temperatures and lower LODs are found for thermal labile nitrate ester explosives (EGDN, NG, ETN, and PETN), while no significant influence of the reduced elution temperature on LODs of more stable explosives, like DNT and TNT, was found.