Determination of trace elements in plant materials by a dry-ashing procedure. Part II. Copper, manganese and zinc

Abstract

A method is described for determining copper, manganese and zinc in ashed plant extracts by flame atomic-absorption spectrophotometry after cobalt and molybdenum have been assayed on separate aliquots of the same plant extracts. Ashing aids were necessary to maintain accuracy in the determinations. Concentrations of up to 3.5%m/m of silicon and calcium and 4%m/m of chlorine in the plants did not affect the determinations, but in some instances lower concentrations were determined in plant samples containing equal or higher levels of both added silica and calcium.

Potential interference was prevented during assays for copper by automatic background correction, for manganese and zinc by diluting the extract, and for all three analytes by selectively matching their chemical matrices with hydrochloric acid and potassium sulphate concentrations in respective working standards. By these procedures, assays for the three elements were similar to determinations by flame atomic-absorption spectrophotometry on samples digested by a standard wet-digestion method.