Liquid-solid sample preparation in drug analysis.

This article compares liquid-solid extraction (LSE) with the more conventional liquid-liquid extraction (LLE) for the preparation of biological samples for assay. The commercially available manual LSE methods, Sep-Pak and Bond Elut, as well as the automated instruments Prep and Analytichem Automated Sample Processor (AASP), are reviewed. Using examples from the literature and the authors' own experiences a practical guide is given to the advantages and disadvantages of LSE.