[Interlaboratory Study on Zinc Test for Food-Contact Rubber Products]

Using six kinds of zinc solution in water and 4% acetic acid as samples, an interlaboratory study was performed to evaluate a zinc (Zn) test method for food-contact rubber products, based on the Japanese Food Sanitation Law. Eighteen laboratories participated, and quantified Zn in six test solutions as blind duplicates using flame atomic absorption spectrometry, induced coupled plasma-optical emission spectrometry or induced coupled plasma-mass spectrometry. Statistical analysis revealed that the trueness, repeatability (RSDr) and reproducibility (RSDr) were 97-103%, 0.7-4.9% and 1.7-8.9% by all measuring methods. The values of the performance parameter fulfilled the target value (trueness: 80-110%, RSDr: 10%, RSDr: 25%). The performance of these methods is sufficient for testing the adherence of samples to the specifications.