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Joanna Kowalska, Anna Jeżewska
Centralny Instytut Ochrony Pracy – Państwowy Instytut Badawczy

Abstract
3,3'-Dichlorobenzidine (DCB), a chlorinated primary aromatic amine, is a grey to purple crystalline solid at room temperature. It is used primarily for the production of pigments for printing inks, textiles, paints, plastics and crayons. It is added as a compounding ingredient to rubber mixtures and plastics. It can also be used alone and in blends with 4,4'-methylenebis(2-chloroaniline) as a curing agent for liquid-stable polyurethane elastomers. 3,3-Dichlorobenzidine has been assigned a “Carc. 1B” hazard class, pursuant to Regulation EC No 1272/2008, and it can affect humans when inhaled and by passing through the skin. 3,3’-Dichlorobenzidine occurs in the working environment in Poland; however, there are no established methods for its determination at low concentration levels. Therefore, a sensitive method for the determination of DCB at the workplace air was being developed and presented in the paper. The sampling method is based on the adsorption of DCB on sulphuric acid-treated glass fiber filters. Sample preparation covers elution of the deposited substance from filter with water followed by sodium hydroxide, carrying out liquid-liquid extraction using toluene in order to enrich the analyte and solvent exchange to acetonitrile, after evaporation of toluene in a nitrogen stream. Determination of the amine in acetonitrile was carried out by means of liquid chromatography (HPLC) with diode assay detector (DAD). Chromatographic determination was conducted in a reverse phase system on Ultra C18 column (250 mm x 4.6 mm; 5 µm). The method developed in this study enables to determine the content of 3,3’-dichlorobenzidine in the presence of other hazardous substances, such as benzidine, aniline, 3,3’-dimethylbenzidine, 3,3’-di¬methoxybenzidine, 4-aminoazobenzene and 4,4’-methylenebis(2-chloroaniline). A standard curve was prepared with reference to the sample preparation for the analysis, which shortens the analysis duration time and reduces the consumption of reagents. In the range of concentrations (1.42-28.4 µg /ml), the resulting standard curve is linear. This method makes it possible to determine the concentration of 3,3’-dichlorobenzidine in the air at a workplace within the concentration range of 0.002 to 0.039 mg/m3 (for air sample volume of 720 L). Air samples are stable for at least ten days. The method is characterized by good overall precision of the examination (5.85%) and meets the criteria for the chemical agents measurement procedures, listed in EN 482. The limit of detection (LOD) amounts to 0.81 ng/ml, whereas the limit of quantitation (LOQ) is 2.44 ng/ml. The developed quantitative method for the determination of concentrations of 3,3’-dichlorobenzidine in workplace air can be used to assess the occupational risk associated with working in the presence of this carcinogen.

Słowa kluczowe
3,3’-dichlorobenzydyna, chromatografia cieczowa, metoda analityczna, stanowisko pracy, analiza powietrza, czynnik rakotwórczy

The Use of Chromatographic Techniques for the Determination of 3,3'-Dichlorobenzidine in Workplace Air

Key words 
3,3’-dichlorobenzidine, liquid chromatography, analytical method, workplace, analysis of air, carcinogen

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