Interlaboratory determination of copper, chromium and arsenic in timber treated with preservative

Abstract

Precision analyses of timber treated with preservative are an important part of quality control in the New Zealand timber preservation industry. Determinations of Cu, Cr and As remain important criteria in this industry. Repeatability and reproducibility values for two interlaboratory trials are calculated. The repeatability for the Rotorua interlaboratory trial ranged from 0.0109 to 0.0497% for Cu, 0.0190 to 0.600% for Cr and 0.0121 to 0.0346% for As, while reproducibility values ranged from 0.0121 to 0.0663% for Cu, 0.0389 to 0.1951% for Cr and 0.0342 to 0.1298% for As. The Queensland interlaboratory trial also produced repeatability and reproducibility values similar to those for the Rotorua trial. Significant differences between laboratories were found for the determination of Cu, Cr and As. Overall, the data from both interlaboratory trials were similar. Increased awareness of quality assurance programmes is seen as essential to improve the performance of laboratories involved in the timber preservation industry.