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

The determination of Cr in digest solutions of mussels and non-fat milk powder by tungsten coil electrothermal atomic absorption spectrophotometry (TC-ETAAS) is affected by interferences. This study reports a critical evaluation of chemical modifiers that could be employed to correct these interferences. The chemical modifiers tested were: Mg [as Mg(NO(3))(2)], Pd [as Pd(NO(3))(2)], NH(4)NO(3), ascorbic acid, and mixtures of these compounds. The less effective modifier was NH(4)NO(3). The best effects, considering thermal stabilization and sensitivity, were obtained in mixtures of ascorbic acid plus Mg. Chromium was determined by TC-ETAAS in certified reference materials of mussels and non-fat milk powder, and results were comparable with those obtained by graphite furnace atomic absorption spectrophotometry (GFAAS).