Griest, WH; Guzman, C; Dekker, M
Separating highly explosive compounds by means of supercritical fluid chromatography (SFC) was examined. 2,6-Dinitrotoluene (606202) (26DNT), 2,4-dinitrotoluene (121142) (24DNT), nitroglycerin (55630), 2,4,6-trinitrotoluene (118967) (TNT), pentaerytheritoltetranitrate (78115) (PETN), N-methyl-N-2,4,6-tetranitroaniline (479458) (TETRYL), hexahydro-1,3,5-trinitro-1,3,5-triazine (121824) (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (2691410) (HMX) were injected into an SFC system consisting of a capillary deltabond cyano column and a variable wavelength ultraviolet absorbance detector. Carbon-dioxide was used as the carrier. The carbon-dioxide was initially at a pressure of 162 atmospheres (atmos) and was programmed to increase to a pressure of 350atmos during a chromatographic run. Retention times, capacity factors, selectivity values, and peak resolution values for 26DNT, 24DNT, nitroglycerin, TNT, PETN, TETRYL, and RDX were tabulated. Except for RDX, the peaks were reasonably symmetric and well resolved. 26DNT was the first to elute, followed by 24DNT, nitroglycerin, TNT, PETN, TETRYL, RDX, and HMX in that order. The elution order generally paralleled increases in molecular polarity and molecular weight. The authors conclude that SFC can achieve good separation of explosive compounds. The separations are more selective than those obtained by high performance liquid chromatography.