Application of photoassisted electrochemical detection to explosive-containing environmental samples

High-performance liquid chromatography (HPLC) with ultraviolet (UV) absorbance and photoassisted electrochemical detection (PAED) is applied to the determination of explosives in groundwater and soil samples. On-line, solid-phase extraction minimizes sample pretreatment, enabling direct analysis of groundwater samples and soil extracts. Soils are extracted using pressurized fluid extraction, which is compared to the Environmental Protection Agency (EPA) sonication method. Limits of detection for explosives in the matrixes of interest are equivalent or superior (i.e., <10 parts-per-trillion for HMX) to those achieved using the EPA method 8330. HPLC-UV-PAED is also shown here to be more broadly applicable, as it is capable of determining nitro compounds of interest (e.g., nitroglycerin) that have poor UV chromophores. Additional selectivity of amine-substituted nitroaromatic explosives is achieved by using a photochemical reactor with a 366-nm wavelength lamp. By coupling reversed-phase columns of different selectivities together, baseline resolution of all 14 standard explosives is demonstrated.