Atomic absorption determination of zinc, copper, cadmium, and lead in tissues solubilized by aqueous tetramethylammonium hydroxide

Abstract Rat liver and kidney homogenates and homogeneous rat hair samples were prepared for atomic absorption spectrophotometric analysis by digestion with an appropriate concentration of aqueous tetramethylammonium hydroxide (TMAH). The endogenous tissue levels of Zn, Cu, Cd and Pb, the reproducibility of the analyses, and the recovery of added metal standards compare favorably with the results obtained by standard wet ashing procedures using concentrated nitric acid or nitric-perchloric acids. The use of 5% HNO 3 standard curve in calculations for the TMAH-treated samples leads to slightly lower results compared to the method of additions due to viscosity and surface tension effects on the aspiration rate of these samples. Moreover, the TMAH digestion method allows faster and safer processing and handling of samples in comparison to acid digestion procedures.