Nitrobenzene. Determination in workplace air

Abstract

Nitrobenzene is a pale yellow oil with an almond-like odor. On an industrial scale it is obtained by nitration of benzene with a mixture of concentrated sulfuric acid, water and nitric acid. The compound is used in the production of aniline. Nitrobenzene is possibly carcinogenic to humans. The aim of this study was to develop a method for determining concentrations of nitrobenzene in workplace air in the range from 1/10 to 2 of MAC values. The developed method is based on the adsorption of nitrobenzene on a silica gel, extraction with methanol and chromatographic analysis of the resulting solution. The tests were performed using a liquid chromatograph (HPLC) 1200 series of Agilent Technologies with a diode array detector (DAD). Determinations were performed using an Ultra C18 column (25 cm × 4.6 mm, dp = 5 µm). The procedure was validated according to Standard No. EN 482. On the basis of obtained results, the concentration range was established as 1.8–36 µg/ml, which corresponds to 0.1–2 mg/m3 for 18-L air sample. In the following range, the obtained calibration curve was linear, as evidenced by the regression coefficient at the level of 1. The overall accuracy of the method was 5.38% and its relative total uncertainty was 23.42%. This method enables selective determination of nitrobenzene in workplace air at concentrations of 0.1–2 mg/m3 in the presence of other compounds, such as methanol, benzene and aniline. The method for determining nitrobenzene is presented in the form of analytical procedure in the Annex.