Liquid chromatography with photolysis–electrochemical detection for nitro-based high explosives and water gel formulation sensitizers

Publisher Website
Google Scholar
Abstract
The use of high performance liquid chromatography with photolysis–electrochemical detection (LC-hv-EC) for conventional high explosives has been improved through the use of a knitted open tubular (KOT) photolysis chamber geometry. Improvements in the analytical figures of merit and selectivity of this hybrid analytical technique are a direct result of the improved radial mass transfer of analyte in the KOT reactor, as demonstrated in comparisons with the coiled reactor geometry previously used. Using the KOT photolysis chamber geometry in LC-hv-EC, the limits of detection for aromatic C-nitro compounds, nitramines and nitrate esters are in the range of 120- to 250- pg injected. In addition, an off-line, pre-column chemical derivatization has been developed to convert water gel sensitizer residues to a form which will allow for their determination using LC-hv-EC. In a rapid, single-step process, 2,4-dinitrofluorobenzene (Sanger's reagent) is used to derivatize residues of monomethylamine and monoethanolamine to their 2,4-dinitrophenyl analogues. Under the preliminary conditions reported here, monomethylamine may be quantitatively converted and detected at concentrations between 200-parts per billion and 50-parts per million. Monoethanolamine is detected with-about 35% derivatization efficiency at levels between 10- and 200-parts per million. The preliminary results suggest that this methodology may be easily improved to allow for the trace determination of water gel sensitizers in aqueous extracts of post-blast debris.