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

A 6% (m/v) slurry of polytetrafluoroethylene (PTFE) in 4% HNO3 was used as a chemical modifier for direct determination of trace cadmium in solid biol ogical samples by slurry sampling electrothermal atomic absorption spectrom etry (ETAAS). Because of the presence of PTFE, an ashing temperature of 800 degrees C was attained with no loss of cadmium within 50 s, In this case, the main coexisting components in solid biological samples did not interfer e with the cadmium determination. The process of cadmium vaporization and a tomization with PTFE/HNO3 is discussed. Under the optimum conditions, the c alibration graph was Linear from 1 to 10 ng ml(-1) with relative standard d eviations of 1.9% for 10 ng ml(-1) and 7.8% for 1 ng ml(-1) Cd (n=5). The d etection limit and characteristic mass were 0.12 and 0.85 pg of Cd, respect ively. The contents of cadmium in some solid biological reference materials were determined by the proposed method with aqueous calibration, and no ch emical pretreatment was necessary. The determined values were in good agree ment with the certified values. (C) 1999 Elsevier Science B.V. All rights r eserved.