Two-step hollow fiber-based, liquid-phase microextraction combined with high-performance liquid chromatography: a new approach to determination of aromatic amines in water.

A novel method for the extraction of aromatic amines present in water samples is produced here coupling two-step liquid-phase microextraction with high performance liquid chromatography by using a monolithic column. The hydrophobic porous polypropylene membranes were used as the interface between the donor water sample and the acceptor aqueous solution. In the first step, the analytes were extracted from a sample solution (pH 13) as donor phase into the organic phase, benzyl alcohol-ethyl acetate (80-20%, v/v) immobilized in the pores of a polypropylene dish and further into an acidified acceptor phase (pH 2) inside the polypropylene membrane. This step had about 100% relative recovery with an enrichment factors of over 59.9. For the second step, using a single piece of polypropylene hollow fiber, was shaped with a star liked profile as the acceptor phase. The acceptor solution in the first step was the donor phase for the second step. This solution was adjusted again to pH 13 with NaOH solution. Five microlitres of HCl solution (pH 2) as the acceptor phase was added to the hollow fiber, star liked profile, as the acceptor phase. This acceptor solution, after the second extraction step, was subsequently withdrawn into a micro syringe and directly injected into an HPLC system for analysis. With this two-step microextraction, total enrichment factors of >6000 could be obtained and detection limits of < or = 250.0 ng/l (S/N = 3)could be achieved. The calibration curves for analytes were linear within the range of 20.0 ng/l to 300 microg/l. All expreriments were carried out at room temperature, 22 +/- 0.5 degrees C.