Determination of As, Cd, Ni and Pb in human hair by electrothermal atomic absorption spectrometry after sample treatment with tetramethylammonium hydroxide

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A very simple alternative dissolution procedure for a human hair sample with tetramethylammonium hydroxide was proposed. The sample was mixed with a small amount of the reagent and the dissolution occurred in approximately 2 h at room temperature or in approximately 10 min under heating at 60–70°C. After dissolution, the analytes, As, Cd, Ni and Pb were determined in a certified reference human hair by electrothermal atomic absorption spectrometry, using calibration curves obtained by separately pipetting the analyte, the modifier and the reagent solutions into the graphite tube. A mixture of Pd and phosphate for Pb and Pd alone for As and Cd were used as modifiers, while no modifier was employed for Ni. The temperature program was optimized through pyrolysis and atomization curves. The limits of detection in the sample were 0.4, 0.009, 0.1 and 0.5 ppm, respectively, for As, Cd, Ni and Pb. The relative standard deviations were lower than 5%. The obtained concentrations agreed with the certified values and also with the found concentrations by using a conventional acid dissolution.