Development of new reference materials for the determination of cadmium, chromium, mercury and lead in polycarbonate

Reference materials for quantitative determination of Cd, Cr, Hg and Pb in polycarbonate were developed. Reference materials with two concentration level of elements were prepared by adding appropriate amounts of chemicals to a blank polycarbonate base material. It was shown that ten bottles with triplicate analysis are enough to demonstrate the homogeneity of these candidate reference materials. The statistical results also showed no significant trends in both short-term stability test for four weeks and long-term stability test for twelve months. The certification of the four elements was carried out by isotope-dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) with microwave-assisted digestion. Certification of candidate reference materials in a single laboratory was confirmed with interlaboratory comparison participated by a certain number of well-recognized testing laboratories in Korea. The certified values and expanded uncertainties (k = 2) for the candidate reference material with low level and the one with high level were (51.7 ± 2.1) mg kg−1 Cd, (103.8 ± 2.9) mg kg−1 Cd, (98.8 ± 4.5) mg kg−1 Cr, (1004 ± 49.8) mg kg−1 Cr, (107.4 ± 4.6) mg kg−1 Hg, (1133 ± 50.7) mg kg−1 Hg, (94.8 ± 3.7) mg kg−1 Pb and (988.4 ± 53.6) mg kg−1 Pb, respectively. The reference materials developed in this study demonstrated their suitability for the quality assurance in Cd, Cr, Hg and Pb analysis for the implementation of RoHS Directive.