Analysis of new generation explosives in the presence of U.S. EPA Method 8330 energetic compounds by high-performance liquid chromatography

U.S. EPA Method 8330 was evaluated and modified for the analysis of DNAN (2,4-dinitroanisole) and MNA (n-methyl-p-nitroaniline) by high-performance liquid chromatography in various aqueous media in the presence and absence of the 14 energetic compounds currently assigned to the method. DNAN and MNA are two of the four components in PAX-21, a new generation explosive formulation. An optimized method was developed to separate all 14 energetic compounds from DNAN and MNA using a tertiary mobile phase of water-methanol-acetonitrile (68:28:4) in an isocratic run of 35 min. The limit of detection (LOD, 3S0) was calculated to be 10 ppb for both MNA and DNAN. The limit of quantitation (LOQ, 10S0) was 40 ppb for both compounds. The dynamic ranges for the two compounds were very wide, a nearly 5 orders of magnitude range from 0.02 to 1,000 parts per million (ppm). The spike recoveries of MNA and DNAN in environmental matrix samples were excellent for DNAN, from 87% to 113%. For MNA, the recoveries were slightly high at the low level (60 ppb), probably due to some contamination in the ditch and pond matrices; but they were satisfactory at higher levels ranging from 85% to 121%.