Development of a simple in-vial liquid-phase microextraction device for drag analysis compatible with capillary gas chromatography, capillary electrophoresis and high-performance liquid chromatography

A simple, inexpensive and disposable device for liquid-phase microextractio n (LPME) is presented for use in combination with capillary gas chromatogra phy (GC), capillary electrophoresis (CE) and high-performance liquid chroma tography (HPLC). 1-4 mi samples of human urine or plasma were filled into c onventional 4-ml vials, whereafter 15-25 mu l of the extraction medium (acc eptor solution) was filled into a short piece of a porous hollow fiber and placed into the sample vial. The drugs of interest were extracted from the sample solutions and into the small volumes of acceptor solution based on h igh partition coefficients and were preconcentrated by a factor of 30-125. For LPME in combination with GC, the porous hollow fiber was filled with 15 mu l n-octanol as the acceptor solution. Following 30 min of extraction, t he organic acceptor solution was injected directly into the GC system. For LPME in combination with CE and HPLC, n-octanol was immobilized within the pores of the hollow fiber, while the internal volume of the fiber was fille d with either 25 mu l of 0.1 M HCl (for extraction of basic compounds) or 2 5 mu l 0.02 M NaOH (for acidic compounds). Following 45 min extraction, the aqueous acceptor solution was injected directly into the CE or HPLC system . Owing to the low cost, the extraction devices were disposed after a singl e extraction which eliminated the possibility of carry over effects. In add ition, because no expensive instrumentation was required for LPME, 10-30 sa mples were extracted in parallel to provide a high number of samples per un it time capacity. (C) 2000 Elsevier Science BN. All rights reserved.