Characterization of nitrophenols in river, lake, and field water samples using dispersive liquid-liquid microextraction

Nitrophenols, a group of poorly degradable pollutants, are produced by chemical industries such as those for dyes, agriculture, and medicine. Two approaches, namely (1) surfactant-assisted dispersive liquid-liquid microextraction (SADLLME) and (2) up-and-down-shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME), were applied to detect four nitrophenols in river, lake, and field water. Both methods used ultra-high-performance liquid chromatography with photodiode array detection (UPLC-PDA). Under optimum conditions, the linear ranges were 1-1000gL(-1) for SADLLME and 2-1000gL(-1) for UDSA-DLLME. The correlation coefficients of the calibration curve were all above 0.9966. The limits of detection (LODs) ranged from 0.1 to 2.6gL(-1). The precisions of determination of spiked analytes were 3.0-6.4% (intraday) and 8.7-14.6% (interday). For the analysis of the three water samples, the relative recoveries ranged from 93.1 to 103% with SADLLME, and from 90.5 to 107% with UDSA-DLLME. Compared with the vortex-assisted method and the method aided by ultrasound emulsification, UDSA-DLLME had better precision, and SADLLME had better sensitivity and lower LODs. The proposed methods offer high sensitivity and minimal consumption of organic solvent. They are alternatives for determining nitrophenols in aqueous samples.