Determination of explosives and some metabolites of TNT in biological and environmental samples by liquid chromatography on a mixed-mode C-18-anion column

This method employs a ternary gradient generated from (1) a 90:10 water:methanol solution that is 0.015 M in potassium phosphate at pH 5.1; (2) methanol; and (3) acetonitrile to separate fifteen explosives, byproducts, and metabolites of 2,4,6-trinitrotoluene (TNT) on a C-18/anion exchange stationary phase. TNT, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), six reduction metabolites and three oxidation metabolites of TNT have been separated and quantitated in a single chromatographic run. Because of the anion exchange character of the stationary phase, the anionic TNT metabolite 2,4,6-trinitrobenzoic acid also may be separated and quantitated using this method. Quantitation limits generally lower than 1 ppm have been established by a systematic certification procedure. The performance of the mixed mode separation method combined with diode array ultraviolet absorbance detection has been demonstrated with samples derived from both biological (tissues and physiological fluids) and environmental (soil, composts, and leachates) sources.