Inductively coupled plasma-atomic emission spectrometry method for determination of trace metals in alkaline-earth matrices after flotation separation

An inductively coupled plasma-atomic emission spectrometry (ICP-AES) method is developed for determination of Cd, Co, Cr, Cu, Ni, Tl and Zn in traces in calcite, CaCO3, dolomite, CaMg(CO3)2, and gypsum, CaSO4. Interferences of a Ca/Mg matrix on analyte intensities were investigated. The results reveal that Ca does not interfere with Cr, Ni and Zn, but tends to decrease the intensity of the other elements. Magnesium as a matrix element does not interfere on with Zn, but increases the intensities of Ni, Cr and Cu, and decreases the intensities of Cd, Co and Tl. To eliminate these matrix interferences on trace element intensities, a flotation separation method is proposed. Lead(II) hexamethylenedithiocarbamate, Pb(HMDTC)2, is applied as a collector for flotation of trace elements from acidic solutions of mineral samples. The flotation of acidic aqueous solutions of calcite, dolomite and gypsum was performed at pH 6.0, using 10 mg l−1 Pb and 0.3 mmol l−1 HMDTC− added to 1 l of solution tested. The method detection limits of analytes in different minerals range from 0.02 to 0.06 μg g−1 for Cd, 0.04 to 0.10 μg g−1 for Co, 0.03 to 0.13 μg g−1 for Cr, 0.02 to 0.16 μg g−1 for Cu, 0.09 to 0.30 μg g−1 for Ni, 6.45 to 7.71 μg g−1 for Tl and 0.18 to 0.20 μg g−1 for Zn.