Simultaneous determination of five nitroaniline and dinitroaniline isomers in wastewaters by solid-phase extraction and high-performance liquid chromatography with ultraviolet detection

A high-performance liquid chromatography (HPLC)-ultraviolet detection method, combined with solid-phase extraction (SPE), was developed for the determination of five nitroaniline and dinitroaniline isomers including 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline and 2,6-dinitroaniline in wastewater samples Extraction of the five isomers was carried out with a hydrophile-lipophile balance cartridge, the Oasis HLB The cartridge was washed by a mixed aqueous solution containing 10% (v/v) acetonitrile and 10% (v/v) ethyl acetate before the five isomers were eluted by a mixture of methanol and acetic acid. Separation of the five isomers was achieved by using an Agilent TC-C(18) column at 30 degrees C, and using a mixture of acetonitrile/water 30/70 (v/v) as mobile phase under an isocratic condition at a flow rate of 10 mL min(-1) The analytes were detected by a UV detector at a wavelength of 225 nm Recoveries of the five isomers in the spiked sewage sample were between 84.6% and 94 0% with a relative standard deviation of less than 4.7%. The limits of quantification (LOQ) determined in a spiked sewage sample of 500 mL were 2.0 x 10(-9) M for 2-nitroaniline. 3-nitroaniline and 2,6-dinitroaniline, and 45 x 10(-9) M for 4-nitroaniline and 2,4-dinitroaniline The proposed method was applied to determine the five isomers in real samples of acidic wastewater and printing and dyeing wastewater. (C) 2010 Elsevier Ltd All rights reserved