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J.Health Sci., 46(6), 467-473, 2000
Determination of p-Phenylenediamine and Related Antioxidants in Rubber Boots by High Performance Liquid Chromatography. Development of an Analytical Method for N-(1-Methylheptyl)-N'-phenyl-p-phenylenediamine
Yoshiaki Ikarashi* and Masa-aki Kaniwa
Division of Medical Devices, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
Although p-phenylenediamine (PPD) and related compounds have been used as antioxidants in rubber products, they commonly display sensitizing properties and have been associated with contact dermatitis. N-Substitution of PPD influences the sensitization potential, so it is important to examine which PPD antioxidants are used in commercially available rubber products, to prevent the occurrence of contact dermatitis in sensitized patients. In this study we developed a method for the determination of PPD derivatives, such as N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine (MHPPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) and N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (DMBPPD), using high performance liquid chromatography (HPLC), and investigated the PPD antioxidant content of rubber boots used by farmers. The PPD derivatives were extracted from rubber boots with acetone : chloroform (1 : 1). The extract was loaded then on to a silica-gel column, and eluted with 50 ml of diethylether : hexane mixtures (5 : 95, 10 : 90, 20 : 80 and 50 : 50) in that order. MHPPD and DMBPPD were eluted in the diethylether : hexane (10 : 90) fraction. The recovery of MHPPD by fractionation was 95±8% (n = 5). IPPD was detected in the diethylether : hexane (20 : 80) fraction. Each fraction was evaporated, and the residue was dissolved in dichloromethane and subjected to HPLC with an ODS column and a UV detector (detection wavelength 290 nm). The mobile phase was methanol : water (85 : 15). After fractionation, the retention times of these PPD derivatives were found not to overlap with other rubber additives. The linear calibration curves for MHPPD, DMBPPD and IPPD were obtained over the range of 0.1-400 mu g/ml. Using this method, eight types of rubber boot used by farmers were analyzed. MHPPD was not found in any of the rubber boots, but DMBPPD and IPPD were detected.
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