Direct Determination of Tin in Human Hair by Graphite Furnace Atomic Absorption Spectrometry Using Air Ashing in Graphite Tube

Direct determination of tin in human hair was performed by graphite furnace atomic absorption spectrometry. Human hair was cut into 3-5 mm long and 1-2 mg of the sample was directly introduced into a pyrolytically coated graphite tube, of which the injection hole was enlarged to a diameter of approximately 5 mm. After introduction of the sample, 20 μl of 30 mg Pd/l in 1 mol/l HCl was added as a matrix modifier onto the hair sample. At the ashing stage of the furnace temperature program, air was passed through in the graphite tube at 600 °C for 1 min. By using the air ashing, the appearance times and shapes of the atomization signal of tin in the hair sample were similar to those for aqueous standard tin solution, indicating the possibility of direct calibration against aqueous standard solutions. The addition of Pd and HCl enhanced the absorbance of tin and improved the precision. Analytical results obtained for a hair sample and a hair reference material by the proposed method were in good agreement with those obtained by the conventional acid digestion method or reported values.