| Solid Phase Microextraction (SPME) has been coupled with liquid chromatography to widen its range of application to nonvolatile and thermally unstable compounds, generally limited to SPME-gas chromatography. A method for analysis of nitroaromatic explosives and its degradations products was developed using SPME and high performance liquid chromatography with ultraviolet detection (HPLC/UV), introducing a modified interface that ensure accuracy, precision, reproducibility, high efficiency, unique selectivity and high sensitivity to detection and quantification of explosives from surface soil samples and increased chromatographic efficiency. A pretreatment step was introduced for the soil samples which extracted the target compounds into an aqueous phase. Several parameters that affect the microextraction were evaluated, such as: fiber coating, adsorption and desorption time, desorption mode, stirring rate, the effect of NaCI (salting out) concentration on analyte extraction and the role of various solvents on SPME fiber. Carbowax-templated resin (CW/TPR) and polydimethilsiloxane-divinilbenzene (PDMS-DVB) fibers were used to extract the analytes from the aqueous samples. Explosives were detected at 330 pg concentrations. Effects of daylight and UV radiation were analyzed over soil samples during 1 month and degradations products found were: 1,3,5-TNB, nitrobenzene, 4-ADNT and 2-ADNT. This study demonstrated that SPME-HPLC is a very promising method of analysis of explosives from aqueous samples and has been successfully applied to the determination of nitroaromatic compounds, such as TNT. |
