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

Summary pose an analytical digestion method for trace metal determination (Co, Cr, Cu, Fe, Mn, Ni and Zn) in gallstones, in an attempt to facilitate detection of their origin. The method consists of sample digestion with HNO3 and H2O2 by means of focused microwave. Metals are quantified by inductively coupled plasma atomic emission spectroscopy. The effect of calcium concentration in the analytical solutions was studied. Cu, Fe, Mn and Zn were detected in all the samples analysed and the highest concentrations were obtained for Cu and Fe, especially in black-pigmented gallstones. The reproducibility in terms of %RSD, determined in the gallstones with the lowest metal content, was below 5% for Cu, between 10 % and 15% for Mn and Zn and up to 25% for Fe.