MINIATURIZED SUPPORTED LIQUID MEMBRANE DEVICE FOR SELECTIVE ONLINE ENRICHMENT OF BASIC DRUGS IN PLASMA COMBINED WITH CAPILLARY ZONE ELECTROPHORESIS

A hollow fiber miniaturized supported liquid membrane (SLM) device for sample preparation is connected on-line with capillary electrophoresi s and used for determination of a basic drug, bambuterol, in human pla sma. The analyte is extracted from the outside of the hollow fiber (do nor) through the liquid membrane (pores of the fiber impregnated with organic solvent) into the acceptor solution in the fiber lumen, The pr ocess is driven by differences in pH between the donor and acceptor so lution, The whole volume of the acceptor solution can then be injected into the CZE capillary by using the double-stacking procedure for lar ge volume-injection. Very clean extracts of low ionic strength are obt ained from the SLM treatment, making this sample pretreatment method c ompatible with the CZE double-stacking procedure, which in turn makes it possible to inject large volumes of sample onto the separation capi llary. Good performance of the whole procedure is demonstrated, and de tection limits in the low nanomolar range were obtained in spite of th e relatively weak UV absorbance of bambuterol, Extractions through the miniaturized SLM unit can be performed for 5-6 h without regenerating the fiber, The regeneration procedure was tested, and no relevant cha nges in the performance of the extraction could be found after seven r egenerations, allowing the same fiber to be used for a week.