Determination of Anilines in Water Samples Using Ionic Liquid-Based Single Drop Microextraction Coupled with High Performance Liquid Chromatography

A novel method for the determination of four anilines (aniline, p-nitroaniline, o-nitroaniline, 2, 4-dinitroaniline) in water samples has been developed using ionic liquid-based single drop microextraction coupled with high performance liquid chromatography. The influence of experimental parameters including extraction solvent, the volume of extraction solvent, extraction time, stirring speed, pH value and NaCl concentration of sample solution, extraction temperature was investigated. The optimal experimental conditions were as follows: 9 μL 1-butyl 3-methylimidazolium hexafluorophosphate ([C₄MIM] [PF₆]) as extraction drop, 10.0 mL aqueous sample with 0.33 g-mL^-1 NaCl, pH 9 was extracted for 25 min, stirring at 600 r-min^-1, extraction temperature set at 50°C, then 5 μL sample was injected to HPLC, aniline and o-nitroaniline were detected at 230 nm, p-nitroaniline and 2, 4-dinitroaniline were detected at 360 nm. Under the optimal conditions, good linear relationships were obtained in the concentrations of 0.010-5.000 mg-L^-1 of the anilines with the correlation coefficients of 0.9990-0.9999; the detection limits were 0.002-0.005 mg-L^-1 (S/N = 3); the enrichment factors of [C₄MIM][PF₆] for the four anilines were from 41.8 to 48.0. The proposed method was applied to the determination of the four anilines in tap, river, lake and waste water and recoveries of the four anilines were in the range of 90.1%-103%; RSD were 3.7%-5.9% (n = 5). The method is simple, friendly to environment, sensitive and satisfied to determine real samples.