Rapid gas-chromatographic determination of marking agents added to the industrial plastic explosives in air

Results of the study of the conditions of detection of traces of marking agents added to industrial plastic explosives in air using preconcentration and subsequent analysis on a ECHO-V-IDVS modernized gas chromatograph with a polycapillary column, an ionization detector of a varying selectivity (IDVS), and atmospheric air as a carrier gas are presented. A significant effect of air humidity on the limits of detection for 4-nitrotoluene and 2,3-dimethyl-2,3-dinitrobutane is demonstrated; the highest IDVS sensitivity was observed at the humidity of the carrier gas less than 8.5 mg/m3. For the preconcentration of marking agents, concentrators based on Tenax adsorbent or those produced as metal wire grids coated with a stationary phase are most efficient. The limits of detection for vapors of marking agents in sampling 1 L of air to a concentrator are 22 pg/cm3 for 4-nitrotoluene and 0.1 pg/cm3 for 2,3-dimethyl-2,3-dinitrobutane.