The determination of bismuth in serum and urine by electrothermal atomic absorption spectrometry

A method for the determination of bismuth in serum and urine is presented. The method includes 1 + 1 dilution of the sample with 1 mM EDTA followed by charring in a graphite furnace under an oxygen atmosphere. The use of oxygen results in the formation of more homogeneous bismuth salts (probably bismuth oxides) during charring, and more efficient burning of the protein and organic components of the sample matrix. The procedure formulated is a standard additions method and is verified for serum and urine samples. The method reduces matrix interferences, gives a detection limit of 0.05 μg l^-1, and has a relative standard deviation of less than 5% for bismuth in the reference range of 2.6–6.0 μg l^-1. The method displays a recovery accuracy of 91, 96, and 100% for urine, serum, and aqueous samples, respectively.