Microextraction techniques: a critical review

Sample preparation is an essential step in analysis, greatly influencing the reliability and accuracy of resulted the time and cost of analysis. It is widely accepted that this analytical step is the most labor-intensive and error-prone part of the analytical process. The recent advances in this field have been focused on the miniaturization and integration of sample preparation online with analytical instrumentation, in order to reduce laboratory workload and increase analytical performance. Solid-Phase Microextraction (SPME) ca be considered the first solventless sample microextraction method, invented by Pawliszyn in 1989 . SPME has been widely used in different fields of analytical chemistry since its first applications to environmental and food analysis and is ideally suited for coupling with mass spectrometry (MS). Starting from SPME, other microextraction techniques, such as micro extraction by packed sorbent (MEPS) or gas purge microsyringe extraction (GP MSE) has emerged in the last few years as a powerful sample preparation approach suitable to be easily automated with liquid and gas chromatographic systems applied in a variety of analytical areas (pharmaceutical, clinical, toxicological, environmental and food research). These techniques allow to integrate in a one-step procedure all steps of the conventional liquid– liquid extraction (LLE) such as extraction, concentration, (derivatization) and transfer to the chromatograph, considerably simplifying the sample preparation procedure. In this presentation, a critical comparison of microextraction techniques will be carried out, considering also the recent innovation in these fields.