Simultaneous determination of organic and cationic species in explosives residues with column-switching liquid chromatography-ion chromatography system.

A new column-switching method has been proposed for the determination of 14 organic explosives (1,3,5,7-tetranitro-N-methylaniline, 1,3,5-trinitro-1,3,5-triazacyclohexane, 1,3,5-trinitrobenzene, 1,3-dinitrobenzene, nitrobenzene, 2,4,6-N-tetranitro-N-methylaniline, Trinitrotoluene, 4-amino-2,6-dinitrotoluene, 2-amino-4,6-dinitrotoluene, 2,6-dinitrotoluene, 2,4-dinitrotoluene, 2-nitrotoluene, 4-nitrotoluene, and 3-nitrotoluene) and/or five inorganic cations (Na(+), NH(4)(+), K(+), Mg(2+), and Ca(2+)) using liquid chromatography linked to ion chromatography by a switching valve. The mobile phase was methanol-water (40/60, v/v) for a C18 reversed-phase column and 3 mM of methanesulfonic acid (pH 2.5) for a cation-exchange column, respectively. Under the optimal conditions, the 14 organic explosives and the five inorganic cations were separated and detected simultaneously within 45 min. The limits of detection (S/N = 3) of the 14 organic explosives and the five inorganic cations were in the range of 0.0048-0.0333 mg/L and 0.0116-0.1851 mg/L, respectively. The linear correlation coefficients were 0.9971-0.9999, and the relative standard deviation of the retention time and the peak area were 0.02-0.31% and 0.51-3.64%, respectively. The method was successfully applied to the determination of organic explosives and inorganic cations in dust samples.