The extraction and determination of copper, chromium and arsenic in preserved softwoods

Abstract

A method is described for the rapid extraction and determination of copper, chromium and arsenic in preservative-treated softwoods. A saw cut is made through the cross-section of the sample and the preserving compounds are leached quantitatively from the sawdust with a mixture of dilute sulphuric acid and hydrogen peroxide solution. Copper, chromium and arsenic in aliquots of the leach solution are allowed to react with zinc dibenzyldithio-carbamate, diphenylcarbazide and ammonium molybdate-hydrazine reagent, respectively, and the determinations are completed by the spectrophotometric measurement of the coloured complexes formed.

The procedure has been used to determine copper, chromium and arsenic in the cross-sections of preserved Baltic redwood, Douglas fir, lodgepole pine and silver fir.