TRACE ANALYSIS OF EXPLOSIVES IN SEAWATER USING SOLID-PHASE MICROEXTRACTION AND GAS-CHROMATOGRAPHY ION-TRAP MASS-SPECTROMETRY

Complex matrixes typically cannot be analyzed directly to obtain the s electivity and sensitivity required for most trace analysis applicatio ns. To circumvent this problem, solid-phase microextraction (SPME) tec hniques were used to preconcentrate analytes selectively prior to gas chromatographic/ion trap mass spectrometric analysis. This approach wa s applied to the trace analysis of explosives and their metabolites in seawater. The choice of SPME sorbent phase was shown to be important especially for the amino metabolites of trinitrotoluene (TNT) and RDX, which were extracted better on polar phases. Although equilibration t imes were quite lengthy, on the order of 30 min or greater, a sampling time of only 10 min was shown to be sufficient for achieving low part -per-billion (ppb) to part-per-trillion (ppt) detection limits for TNT and the amino metabolites in real seawater samples. While SPME was id eal for rapid screening of explosives in seawater samples, methods for improving the reproducibility and accuracy of quantification are stil l being investigated.