Correction of matrix effects in the analysis of stream waters by flameless atomic absorption spectrophotometry

Direct injection techniques to measure trace metal concentrations by flameless atomic absorption were applied to fresh water samples of low to moderate matrix content. Many samples exhibited high non-atomic absorption which was decreased considerably by HNO₃ digestion within the furnace. The remaining background absorption could not be reduced by selective volatilization prior to atomization. It was taken into account where necessary by background measurements at nearby non-absorbable wavelengths.Other interference problems applying especially to Cd, Pb and Zn were eliminated by operating at higher than usual atomization temperatures. The method of standard additions to calibrate concentrations seemed to be adequate for these particular samples.Using the method recommended, precision tests to measure “within batch” and “between batch” variations were carried out for four elements in a typical sample.