Direct determination of cadmium in solid biological materials by slurry sampling electrothermal atomic absorption spectrometry with polytetrafluoroethylene as a chemical modifier

Abstract

A 6% (m/v) slurry of polytetrafluoroethylene (PTFE) in 4% HNO 3 was used as a chemical modifier for direct determination of trace cadmium in solid biological samples by slurry sampling electrothermal atomic absorption spectrometry (ETAAS). Because of the presence of PTFE, an ashing temperature of 800°C was attained with no loss of cadmium within 50 s. In this case, the main coexisting components in solid biological samples did not interfere with the cadmium determination. The process of cadmium vaporization and atomization with PTFE/HNO 3 is discussed. Under the optimum conditions, the calibration graph was linear from 1 to 10 ng ml −1 with relative standard deviations of 1.9% for 10 ng ml −1 and 7.8% for 1 ng ml −1 Cd ( n=5). The detection limit and characteristic mass were 0.12 and 0.85 pg of Cd, respectively. The contents of cadmium in some solid biological reference materials were determined by the proposed method with aqueous calibration, and no chemical pretreatment was necessary. The determined values were in good agreement with the certified values.