A LC-MS method allowing the analysis of HMX and RDX present at the picogram level in natural aqueous samples without a concentration step.

The introduction of chloroform into the nebulising gas of a LC/MS electrospray interface (ESI), in a perfectly controlled way, leads to the formation of intense adducts ([M+Cl]−) when a mobile phase containing HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane or octogen) and RDX (1,3,5-trintro-1,3,5-triazacyclohexane or hexogen) is eluted. This LC/MS method allows the direct analysis of aqueous samples containing HMX and RDX at the pictogram level without a concentration step. The method is used to determine HMX and RDX concentrations in ground water samples from a military site.