Development of PVC and PP Resin Pellet Certified Reference Materials for Heavy Metal Analysis with Respect to the RoHS Directive

Abstract

The PVC (polyvinyl chloride) and the PP (polypropylene) resin pellet certified reference materials (CRMs, NMIJ CRM 8123-a and 8133-a) with respect to the RoHS (restriction of the use of hazardous substances in electrical and electronics equipment) directive were developed in the present study. Both the sample pretreatment and the measurement procedures for the determination of Cd, Cr, Hg and Pb in the PVC and the PP resin pellets were examined, and several analytical methods were developed. Microwave acid digestion and dry-ashing followed by acid digestion procedures were examined as sample pretreatment procedures. In the case of measurement procedures, an inductively coupled plasma mass spectrometry (ICPMS) including an isotope dilution mass spectrometry (IDMS) and an ICP optical emission spectrometry (ICPOES) were used. Since the analytical results obtained by different analytical methods showed good agreement within their uncertainties estimated, it was concluded that the analytical methods established in this study were reliable with high accuracy. The homogeneity and the stability of Cd, Cr, Hg and Pb in these plastic CRMs were also evaluated, and the results revealed sufficient homogeneity of 0.3 – 0.7% and stability for more than 5 years. From these results, it is considered that these CRMs are useful CRM for the determination of Cd, Cr, Hg and Pb in plastics with respect to the RoHS directive.