New horizons: Explosive detection in soil extracts with a fiber-optic biosensor

Contamination of soils with the explosives TNT and RDX is a worldwide probl em that has resulted from inadequate disposal methods. Many of these contam ination sites are currently being characterized or are undergoing remediati on, The ability to obtain real-time, onsite results would save remediation time, reduce cost, and provide for efficient use of labor during cleanup. T he NRL fiber-optic biosensor, which has been demonstrated for the on-site d etection of explosives in ground water, has expanded its horizons to includ e detection in soil extracts. Soil samples from several sites in the United States were analyzed for TNT and RDX. The explosives were removed from the soil with a 3-min acetone extraction. The extract was mixed with buffer co ntaining a fluorescent explosive analog and exposed to the antibody-coated optical probes. In the presence of either TNT or RDX, a decrease in the flu orescence signal, proportional to the explosive concentration, was observed . In less than 20 min, analysis on four optical probes was completed. Extra ct results from the fiber-optic biosensor were compared to those from U.S, EPA SW 846 Method 8330 (reverse-phase high-performance chromatography), Det ection limits of 0.5 mg/kg (0.1 mg/l) of TNT and RDX in soil acetone extrac ts were obtained. (C) 2000 John Wiley & Sons, Inc.*