INTERLABORATORY DETERMINATION OF BORON-COMPOUNDS IN PRESERVATIVE TREATED TIMBER

Accurate analysis for preservatives in treated timber is an integral part of quality assurance in the New Zealand timber preservation industry. The continued high volume use of boron-treated timber has highlighted the requirement for reliable methods to determine boron-containing preservatives in timber. Several aspects of a leaching-titration method are discussed in an effort to validate and standardize laboratory analysis of samples for the timber preservation industry. Steam volatility was found not to be a problem. The limit of detection was 0.007% (w/w) H3BO3 and the relative standard deviation of 50 replicate analyses was 2.2%. Statistical outliers and stragglers were identified by Cochran's test. The precision data (repeatability and reproducibility) from an interlaboratory determination of boric acid in timber were 0.0133-0.0273 and 0.0194-0.0535% H3BO3, respectively, over six concentration levels. Recommendations for maintaining active quality assurance programmes are made. © 1990.