3,3′-Dimethoxybenzidine. Determination in workplace air

Abstract

3,3′-Dimethoxybenzidine (DMOB) is a substance classified to a group of carcinogens. The recommended maximum admissible concentration (MAC) value for this substance in workplace air is 0.2 mg/m3. The aim of this study was to develop and validate a sensitive method for the determination of 3,3′-dimethoxybenzidine concentrations in workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of the standard PN-EN 482. The method consists in passing the air that contains DMOB through a sulfuric acid-treated glass fiber filters, washing out the substance settled on the filter, using water and solution of sodium hydroxide, liquid-liquid extraction with toluene, replacing dissolvent with acetonitrile and analyzing the obtained solution. Studies were performed using high-performance liquid chromatography (HPLC) technique. An Agilent Technologies (Germany) liquid chromatograph, series 1200, with a fluorescence detector (FLD) was used in the experiment. In the test, an Ultra C18 column of dimensions: 250 x 4.6 mm, with a precolumn of dimensions: 10 x 4.0 mm (Restek, USA) was applied. Method is linear within the working range 1.08 µg/ml do 21.60 µg/ml, which is equivalent to air concentrations from 0.02 to 0.4 mg/m3 for a 54-L air sample. The analytical method described in this paper allows for selective determination of 3,3’-dimethoxybenzidine in the workplace air in the presence of 1,4-phenylenediamine, benzidine, aniline, 3,3’-dimethylbenzidine, 2-nitrotoluene, 3,3’-dichlorobenzidine and azobenzene. The method is characterized by good precision and accuracy and meets the criteria for the performance of procedures for the measurement of chemical agents, listed in EN 482. The method may be used for the assessment of occupational exposure to 3,3’-dimethoxybenzidine and the associated risk to workers’ health. The developed method of determining 3,3’-dimethoxybenzidine has been recorded as an analytical procedure (see appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.