Reduction of extraction times in liquid-phase microextraction

Recently, we introduced a simple and inexpensive disposable device for liqu id-phase microextraction (LPME) based on porous polypropylene hollow fibres . In the present paper, extraction times were significantly reduced by an i ncrease in the surface of the hollow fibres. The model compounds methamphet amine and citalopram, were extracted from 2.5 ml of urine, plasma, and whol e blood after dilution with water and alkalisation with 125 mul of 2 M NaOH though a porous polypropylene hollow fibre impregnated with hexyl ether an d into an aqueous acceptor phase consisting of 0.1 M HCl. Two commercially available hollow fibres, which differed in surface area, wall thickness and internal diameter, were compared. An increase in the contact area of the h ollow fibre with the sample solution by a factor of approximately two resul ted in reduction in equilibrium times by approximately the same factor. Thu s, the model compounds were extracted to equilibrium within 15 min from bot h urine and plasma, and within 30 min from whole blood. For the first time LPME was utilised to extract drugs from whole blood, and the extracts were comparable with plasma both with regard to sample clean-up and extraction r ecoveries. Extraction recoveries for methamphetamine and citalopram. varied from 60 to 100% using the two fibres and the different matrices. (C) 2001 Elsevier Science BV All rights reserved.