Application of Experimental Design in Acid Digestion Optimization for Cd, Cr, and Pb Determination in Plastic Materials by Atomic Absorption Spectrometry

摘要

A simple and reliable method for Cd, Cr, and Pb determination in plastic materials using an optimized wet acid digestion procedure and flame atomic absorption spectroscopy (FAAS) was developed. In order to obtain the best experimental conditions for plastic acid digestion, a 2(6-3) factorial design for screening the significant factors, and 2(3) central composite design (CCD) for optimizing the significant experimental variables were carried out. The polyethylene (PE) European Reference Material ERM-EC680 with certified Cd, Cr, and Pb concentration was used in both the screening and the optimization steps. These were the optimized experimental conditions: 0-300 g of plastic material digested with 4 nil, concentrated nitric acid (30 minutes, 155 degrees C) followed by I nil, concentrated perchloric acid (20 min, 175 degrees C). The accuracy and precision were checked Using ERM-EC680. The recovery was from 94.1% (Pb) to 99.1% (Cr), and the relative standard deviation (RSD) was from 1.4% (Cd) to 7% (Cr). The limit of detection (LOD) obtained was front 1.3 mg kg(-1) (Cr) to 3.9 mg kg(-1) (Cr, Pb). The method was applied in the analysis of several commercial packaging materials and plastic toys.