Two-stage probe atomization GFAAS for direct determination of trace Cd and Pb in whole bovine blood

Abstract

Graphite furnace atomic absorption spectrometry (GFAAS) is rarely used for direct trace analysis of whole blood because of strong interferences caused by the organic matrix. Especially it concerns bovine blood samples, containing more proteinaceous and lipid components in comparison with human blood. In our work, the novel two-stage probe atomization (TPA) technique for Cd and Pb determination by GFAAS in whole bovine blood with minimum sample pre-treatment has been developed. Making use of TPA and chemical modifier has eliminated matrix suppression and decreased the non-selective absorption level by several times. It allowed us to dispense with brief sample pre-treatment by a mixture of nitric acid and hydrogen peroxide (1:1) without autoclave digestion. The pyrolysis temperatures were 650 °C for Cd and 900 °C for Pb in the presence of Pd modifier. The analytical signal dependence on the number of concentrating cycles has been studied. The maximal number of capturing cycles was found (15 and 10 for Cd and Pb). Applying of multiple probe concentrating has additionally decreased the limits of detection (LODs) comparing with single TPA. The achievable LODs in optimized conditions were found to be 0.01 and 0.2 μg/L for Cd and Pb, respectively (3 s test). The accuracy of the proposed technique was confirmed by anodic stripping voltammetry (ASV). The relative standard deviation for 5.1 μg/L Cd and 26 μg/L Pb concentrations was 6.4% and 7.5%, respectively.