Abstract

Biological monitoring is one of the most important tools in the prevention of diseases due to toxic agents in the general or occupational environment. Therefore, an essential need for sensitive and selective techniques for the analysis of trace chemical compounds in biological matrices has been clearly recognised. The trace determination of toxic materials and their metabolites in biological matrices such as urine, is faced with a serious problem; Since the complex matrixes might interfere the quality and quantity of the results and influence the life time of the analytical instruments, extraction, purification and pre-concentration of the analytes is essential before a reliable quantitative and qualitative analysis. Conventional sample preparations have some disadvantages such as large volumes of high-purity solvents (in some cases expensive, toxic, or highly polluting), low pre-concentration, multi-step and a long procedure. Recently, a novel microextraction technique as hollow-fibre liquid-phase microextraction (HF-LPME) has been used in different biological samples for different analytes to overcome these problems.

In HF-LPME, the metabolites of interest are extracted from urinary samples, through a thin layer of microlitres organic solvent immobilised within the pores of a porous hollow fibre, and into an acceptor solution inside the lumen of the hollow fibre. The acceptor phase can be an aqueous solution, resulting in a three-phase system compatible with high- performance liquid chromatography, capillary electrophoresis or mass spectrometry, or it can be organic, resulting in a two-phase extraction configuration directly compatible with capillary gas chromatography. For two and three-phase configurations, the migration is pH-dependent in the donor and acceptor phases. In addition to pH gradients, carrier-mediated transport has been reported with LPME extraction. The proposed method has been showed excellent enrichment factor and clean up, a very low limit of detection with wide dynamic linear range in low extraction time for different metabolites.