1984 Volume 33 Issue 9 Pages T91-T94
Complete analyses of multiple oxide minerals such as pyrochlore A2B2O7, betafite AB2O7, and samarskite ABO4, where A represents Ca, Fe, Y, U, Th, etc. and B does Nb, Ta, Ti, etc. by ICP-AES were made with excellent reproducibility. Seventeen elements which occur as major components of above mineral groups, K, Na, Mg, Mn, Fe, Ca, Pb, Y, Zr, Th, U, Al, Sb, Ti, Nb, Ta, and W, were examined. The mineral samples were decomposed with a mixture of sulfuric and hydrofluoric acids, and diluted with dilute sulfuric acid containing hydrogen peroxide. The suppression effect of sulfuric acid on the emission intensity was minimized by keeping the acid-concentration of sample and standard solution the same. The standard solution containing either 6 or 17 elements was used for the calibration. Both have two series of the concentration of each element; 5 ppm and 30 ppm. Corrections for spectral interferences from coexisting elements were made by subtracting the predicted emission intensities due to the interfering elements from the total intensity at the wavelength of the elements to be analyzed. Procedure: Take 510 mg sample into a tared Pt crucible. Add 9 ml of sulfuric acid (1 : 1) and several ml of hydrofluoric acid. Heat to the sulfuric acid fume, cool and weigh the crucible to know the amount of the remaining sulfuric acid. Add necessary sulfuric acid to make the final concentration to be 5 %. Add 2 ml of 30 % hydrogen peroxide and dilute the solution to 100 ml, determine the spectral intensities of elements and apply the necessary corrections.
