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Recently, solid-phase microextraction (SPME) was successfully coupled to high-performance liquid chromatography. However, the efficiency of this analytical method, in terms of manpower, still suffers from its manual operation technique. Furthermore, the selectivity obtained for the analysis of very polar compounds is still poor because of a limited selection of commercially available fiber coatings that can withstand the aggressive HPLC conditions (solvents). This paper describes the first approach to developing an automated SPME-HPLC system. A mixture of polar thermally labile analytes, phenylurea pesticides, was selected for microextraction directly from an aqueous sample. A piece of a ordinary capillary GC column with its coating (Omegawax 250) was used for the absorption of analytes from the aqueous sample (in-tube solid-phase microextraction). A needle hosts the capillary when it is pierced through the septum of the vial containing the spiked aqueous sample. The aqueous samples were stored in 2 mL vials on the tray of a commercial autosampler. A sample of 25 µL was aspirated and dispensed several times from the sample into the capillary using a syringe. After the extraction the absorbed analytes were released from the coating by aspiring methanol into the column and then dispensing the methanol into the HPLC injector loop. The absorption-time profiles, the amounts absorbed by different coatings, linearity, and precision were studied under different sampling conditions using spiked aqueous samples. SPME selectivity for polar compounds, which represent an important compound class for water analysis, can be improved by using more polar column coatings such as Carbowax instead of poly(dimethylsiloxane)-coated columns. Compared to the manual version this automated SPME-HPLC system could increase productivity and reproducibility. Furthermore, the desorption step is quantitative; i.e., no carryover could be detected. This entire method for automated SPME sample preparation is simple and controlled by a commercial autosampler from LC Packings which was modified to operate in-tube SPME. The automated SPME-HPLC device obtains RSD for all investigated compounds below 6%. A simple mathematical model was used to calculate the concentrations vs length profiles in the column for any time. The model was in good agreement with experimental data which was obtained for benzene as a model compound. Thus, the main parameters affecting the partitioning process were determined and the amount absorbed by the coating could be predicted.

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The main objective of this review is to describe the recent developments in solid-phase microextraction technology in food, environmental and bioanalytical chemistry applications. We briefly introduce the historical perspective on the very early work associated with the development of theoretical principles of SPME, but particular emphasis is placed on the more recent developments in the area of automation, high-throughput analysis, SPME method optimization approaches and construction of new SPME devices and their applications. The area of SPME automation for both GC and LC applications is particularly addressed in this review, as the most recent developments in this field have allowed the use of this technology for high-throughput applications. The development of new autosamplers with SPME compatibility and new-generation metal fibre assemblies has enhanced sample throughput for SPME-GC applications, the latter being attributed to the possibility of using the same fibre for several hundred extraction/injection cycles. For LC applications, high-throughput analysis (>1,000 samples per day) can be achieved for the first time with a multi-SPME autosampler which uses multi-well plate technology and allows SPME sample preparation of up to 96 samples in parallel. The development and evolution of new SPME devices such as needle trap, thin-film microextraction and cold-fibre headspace SPME have offered significant improvements in performance characteristics compared with the conventional fibre-SPME arrangement.