Abstract
The ability to separate nitroaromatic and nitramine explosives in seawater sample matrices is demonstrated using both MEKC and CEC. While several capillaryβbased separations exist for explosives, none address direct sampling from seawater, a sample matrix of particular interest in the detection of undersea mines. Direct comparisons are made between MEKC and CEC in terms of sensitivity and separation efficiency for the analysis of 14 explosives and explosive degradation products in seawater and diluted seawater. The use of highβsalt stacking with MEKC results, on average, in a threeβfold increase in the number of theoretical plates, and nearly double resolution for samples prepared in 25% seawater. By taking advantage of long injection times in conjunction with stacking, detection limits down to sub mg/L levels are attainable; however, resolution is sacrificed. CEC of explosive mixtures using solβgels prepared from methyltrimethoxysilane does not perform as well as MEKC in terms of resolving power, but does permit extended injection times for concentrating analyte onto the head of the separation column with little or no subsequent loss in resolution. Electrokinetic injections of 8βmin at high voltage allow for detection limits of explosives below 100β
Β΅g/L.