Application of focused-microwave wet digestion to the determination of trace metals in human gallstones by ICP/AES

We propose an analytical digestion method for trace metal determination (Co , Cr, Cu, Fe, Mn, Ni and Zn) in gallstones, in an attempt to facilitate det ection of their origin. The method consists of sample digestion with HNO3 a nd H2O2 by means of focused microwave. Metals are quantified by inductively coupled plasma atomic emission spectroscopy. The effect of calcium concent ration in the analytical solutions was studied. Cu, Fe, Mn and Zn were dete cted in all the samples analysed and the highest concentrations were obtain ed for Cu and Fe, especially in black-pigmented gallstones. The reproducibi lity in terms of %RSD, determined in the gallstones with the lowest metal c ontent, was below 5% for Cu, between 10% and 15% for Mn and Zn and up to 25 % for Fe.