On-line coupling of in-tube solid phase microextraction (SPME) to HPLC foranalysis of carbamates in water samples: Comparison of two commercially available autosamplers

In-tube solid phase microextraction (SPME) is a new on-line sample preparat ion technique that is easily installed on a conventional high-performance l iquid chromatography (HPLC) autosampler, and has previously been used with the LC Packings FAMOS autosampler without modification of the autosampler i tself. This paper describes the on-line coupling of in-tube SPME to a Hewle tt Packard (HP) model 1100 HPLC autosampler, and reports on several fundame ntal aspects of the technology. The extraction and desorption processes wit h this system were thoroughly studied for a group of carbamate pesticides i n water samples. The similarities and differences of the in-tube SPME techn ique with the two different autosamplers, FAMOS and Hewlett Packard, were c ompared during method development. The optimized conditions were successful ly applied to extract the carbamates of interest from spiked surface, well, and tap water samples, exhibiting excellent method precision. The % relati ve standard deviation (RSD) for all the carbamates studied in the different environmental water samples was between 0.8 and 6.0%. There was no noticea ble extraction efficiency decrease relative to pure laboratory samples when the method was applied to spiked environmental water samples. The method w as found to be linear between 2 and 20,000 mu g/L with correlation coeffici ents in the range of 0.9791 to 0.9991. With respect to the different water samples, the limits of detection (LODs) for all the carbamates studied were in the range of 0.44-17 mu g/L. For carbaryl, the LODs were between 0.44 a nd 0.67 mu g/L, which were lower than those obtained using the in-tube SPME method with the FAMOS autosampler. (C) 2000 John Wiley & Sons, Inc.