Determination of lead in electrolytic tinplate coating by X-ray fluorescence spectrometry
HUANG Gang-ming1, FAN Chun2, TIAN Hui-ling2, WANG Jun-xiang2
1. Department of Manufacture and Management, Baosteel Co., LTD., Shanghai 201900, China; 2.Detection Division, Baosteel Engineers and Technicians Co., Shanghai 201900, China
Abstract：By selecting representative electrolytic tinplate samples with different coating mass and different lead content as calibration sample and adopting method regulated by European Union BS EN 10333-2005 (Steel for packaging-the flat steel products in contact with human and animal food, products and beverages-tinned steel) to determine the lead content in its tin coating, the shortage problem of electrolytic tinplate certified reference materials was solved. Thus, a method for direct determination of lead content in unit tin coating of electrolytic tinplate samples was established by X-ray fluorescence spectrometry. The samples were divided into two layers (substrate layer and tin coating) with film analysis software equipped in the instrument to correct the interference caused by lead in the substrate layer. Fundamental Parameters Method (FP) software equipped in the instrument was used to correct tin interference caused by different unit tin coating mass, so as to the correlation coefficient of the calibration curve reach 0.993. The result indicated the method was suitable for sample with unit tin coating mass more than 2.0 g/m2 and substrate thickness more than 0.2 mm. The proposed method was applied to the determination of actual electrolytic tinplate samples. The results were consistent with those obtained by European Union BS EN 10333 standard method, and the relative standard deviations (n=6) were 4%-20%.
BS EN 10333-2005 Steel for packaging-Flat steel products intended for use in contact with foodstuffs, products or beverages for human and animal consumption-Tin coated steel (tinplate)[S].
