Determination of four aromatic amines in water samples using dispersive liquid-liquid microextraction combined with HPLC

A new method for the determination of four aromatic amines in water samples was developed by using dispersive liquid-liquid microextraction (DLLME) technique combined with HPLC-variable wavelength detection (HPLC-VWD). In this extraction method, 0.50 mL methanol (as dispersive solvent) containing 25.0 microL tetrachloroethane (as extraction solvent) was rapidly injected by a syringe into 5.00 mL water sample. Accordingly, a cloudy solution was formed. After centrifugation for 2 min at 4000 rpm, the fine droplets of the tetrachloroethane containing the analytes were sedimented in the bottom of the conical test tube (7+/-0.2 microL). Then, 5.0 microL of the settled phase was determined by HPLC-VWD. Parameters such as the kind and volume of extraction solvent and dispersive solvent, extraction time, and salt concentration were optimized. Under the optimum conditions, the enrichment factors ranged from 41.3 to 94.5. Linearity was observed in the range of 5-5000 ng/mL. The LODs based on S/N of 3 ranged from 0.8 to 1.8 ng/mL. The RSDs (for 400 ng/mL of p-toluidine and o-chloroaniline, 100 ng/mL of p-chloroaniline and p-bromoaniline) varied from 4.1 to 5.3% (n=6). The water samples collected from rivers and lakes were successfully analyzed by the proposed method and the relative recoveries were in the range of 85.4-111.7% and 90.2-101.3%, respectively.