Determination of Pb, Cr, Cd, and As in Aluminum-Plastic Packaging Materials via Inductively Coupled Plasma-Mass Spectrometry with Microwave Digestion

Microwave digestion was performed to study the pretreatment methods of aluminum-plastic packaging materials (APPMs). Five different digestion reagent combinations and proportions were thoroughly considered. Digestion results indicated that the most suitable reagent combination was sulfuric and nitric acids with the optimal proportion of 1∶7 after the orthogonal experiment. Moreover, the possible reasons of the experimental phenomenon were analyzed. The contents of Pb, Cr, Cd, and As in APPMs were subsequently determined via inductively coupled plasma-mass spectrometry (ICP-MS). The satisfactory linearity of calibration curves was obtained with the linear correlation coefficients above 0.999 5, and the instrument detection limits of Pb, Cr, Cd, and As for the current method were 0.215, 0.067, 0.006 and 0.020 ng·mL-1, respectively. Furthermore, the recoveries of standard addition ranged from 83.8% to 111.6%, and the relative standard deviations ranged from 0.5% to 7.4%. Two independent parallel determination results of Pb, Cr, Cd, and As in APPMs were approaching, and the student’s t-test (confidence level, α=0.05) showed that the determination results had no significant differences. In conclusion, the present method exhibited fine linearity, low detection limit, high recovery, and good precision, which can accurately be utilized to analyze Pb, Cr, Cd, and As elements in APPMs or other similar materials.