Determination of explosives in soil and ground water by liquid chromatography-amperometric detection

Electrochemical reduction of trinitrotoluene (TNT) and several nitroaromati cs has been exploited toward the development of an amperometric detector fo r liquid chromatography (LC). Up to a ten-fold increase in sensitivity was accomplished for the explosives using amperometric detection instead of con ventional UV measurement. A working glassy carbon electrode (poised at -0.8 0 V vs. Ag/AgCl) offered a detection limit of 9, 44 and 550 nM for trinitro benzene, TNT and 1,4-dinitrobenzene, respectively. Separation of eleven TNT -related compounds in a mixture was achieved within 15 min using a C-18 col umn and a mobile phase consisting of acetonitrile-50 mM phosphate buffer pH 5 (1:2, v/v) and 18 mM sodium dodecylsulfate. The LC-amperometric detectio n system was applicable for analyzing soil extracts and ground water and th e results obtained agreed well with that of the US Environmental Protection Agency recommended procedure. Extension to analysis of HMX (octahydro-1,3, 5,7-tetranitro-1,3,5,7-tetrazocine) and RDX (hexahydro-1,3,5-trinitro-1,3,5 -triazine) was accomplished with a silver working electrode instead of a gl assy carbon electrode installed in a thin channel cell. (C) 1999 Elsevier S cience B.V. All rights reserved.