Determination of Nitroaromatic Photodecomposition Products of Tecnazene Using Liquid Chromatography with Amperometric Detection

Abstract

Isocratic liquid chromatographic methods with mobile phases consisting of 20 mmol l-1 sulfuric acid and 60% acetonitrile (for 9 quickly eluted nitroaromatic compounds) or 75% acetonitrile (for 2 strongly retained nitrobenzenes) at a flow rate of 1.2 ml min-1 using a DC amperometric detection with a glassy carbon working electrode at -0.5 V vs Ag/AgCl reference electrode have been developed for the determination of 11 nitroaromatic compounds. The overall repeatability of the retention times was better than 0.5% and the repeatability of the peak areas ranged from 1.2 to 8.3% (n = 7) based on the manual injection of 300 μl of standard solution. Limits of detection (LODs for 3.S/N) of 25-250 nmol l-1 were obtained. The developed methods have been applied to the determination of nitroaromatic decomposition products in the UV-irradiated samples of a tecnazene (1,2,4,5-tetrachloro-3-nitrobenzene) solution. Due to the high selectivity of the DC amperometric detection in reductive mode, no interferences occurred in the analyses of UV-irradiated tecnazene solutions although high concentrations of other compounds (e.g., phenols, chlorophenols, inorganic anions, and carboxylic acids) were present.