Study of chemical modifiers for the determination of chromium in biological materials by tungsten coil electrothermal atomic absorption spectrometry

Abstract

The determination of Cr in digest solutions of mussels and non-fat milk powder by tungsten coil elec- trothermal atomic absorption spectrophotometry (TC- ETAAS) is affected by interferences. This study reports a critical evaluation of chemical modifiers that could be em- ployed to correct these interferences. The chemical modi- fiers tested were: Mg (as Mg(NO3)2), Pd (as Pd(NO3)2), NH4NO3, ascorbic acid, and mixtures of these compounds . The less effective modifier was NH4NO3. The best effects, considering thermal stabilization and sensitivity, were ob- tained in mixtures of ascorbic acid plus Mg. Chromium was determined by TC-ETAAS in certified reference ma- terials of mussels and non-fat milk powder, and results were comparable with those obtained by graphite furnace atomic absorption spectrophotometry (GFAAS).