Liquid-liquid-liquid microextraction of aromatic amines from water samples combined with high-performance liquid chromatography

A simple preconcentration and clean-up liquid-liquid-liquid microextraction of aromatic amines is described in this paper. The compounds were extracted from 2.0 ml aqueous samples (donor phase) into an organic phase, layered on the donor phase, and then back extracted to a microdrop of aqueous receiving phase, suspended in the organic phase. After extraction, the microdrop was injected into the HPLC system directly for analysis. Optimal conditions of the extraction were donor phase (a(1)): 2 ml of water sample adjusted to pH 13 with NaOH-NaCl; organic phase (o), 150 mul ethyl acetate; and receiving phase (a(2)) of 2 mul aqueous solution at pH 2.1. The a(1)-->o extraction time was 15 min and for o-->a(2), 30 s. 18-Crown-6 ether, which can complex with amine, was added to the aqueous receiving phase to improve the extraction performance. Enrichment factors ranged from 218 (for 4-nitroaniline) to 378 (for 4-chloro-2-aniline). The calibration curve for these anilines was linear within the range 2.5 ng/ml-2.5 mug/ml (r(2)=0.998). Detection limits ranged from 0.85 to 1.80 ng/ml (at S/N=3). This procedure can be a selective preconcentration method for aromatic amines present in water samples. (C) 2002 Elsevier Science B.V. All rights reserved.