In-tube solid-phase microextraction coupled to capillary LC for carbamate analysis in water samples

Recently, the on-line sample preparation technique, in tube solid-phase mic roextraction (SPME), was successfully implemented with a Hewlett-Packard 11 00 HPLC system for analysis of carbamates in water samples. This paper desc ribes the coupling of in-tube SPME to capillary LC and explores its utility as a sample preparation method in that format, relative to conventional LC , The Hewlett-Packard HPLC system was upgraded to a capillary LC system usi ng commercially available accessories from LC Packings. The combination of in-tube SPME with a capillary LC system was expected to build on the merits of both in-tube SPME and the capillary LC to generate a sensitive method w ith an easy, effective, and efficient sample preparation. Due to the relati vely large effective injection volume of the in-tube SPME technique (30-45 mu L), on-column focusing was employed in order to achieve good chromatogra phic efficiency. Excellent sensitivity was achieved with very good method p recision. For all carbamates studied, the RSD of retention time was between 0.5 and 0.8% under 4 mu L/min microgradient conditions. The RSD of peak ar ea counts was between 1.5 and 4,6%, The detection limits for all carbamates studied were less than 0.3 mu g/L and, for carbaryl, just 0.02 mu g/L (20 ppt), Compared with the conventional in-tube SPME/LC method, the LODs were lowered for carbaryl, propham, methiocarb, promecarb, chlorpropham, and bar ban, by factors of 24, 45, 42, 81, 62, and 56, respectively. The optimized method was successfully applied to the analysis of carbamates in surface wa ter samples.