Determination of Molybdenum and 4 Major Associated Elements in Large-Scale Molybdenum Polymetallic Ores by Inductively Coupled Plasma Mass Spectrometry

At present, there were some problems with strong detector signal, poor stability, and low accuracy to determine large-scale of constant elements by inductively coupled plasma mass spectrometry (ICP-MS). Therefore, the analytical conditions were optimized and the method mentioned by the title was proposed. 0.05 g of the sample was taken and rinsed with a small amount of water, and a mixture of 4 mL of sulfuric acid and 8 mL of nitric acid was added. After mixing well, the solution was heated to dryness at 250 ℃ for 18 h. After cooling to room temperature, the residue was dissolved in 3-4 mL of 10% (volume fraction) nitric acid solution, and made its volume up to 25 mL with water. The sample solution was diluted 100 times with an automatic dilution system, in which Mo, W, Cu, Zn, and Ag were determined by ICP-MS, reducing physical interference with a dilution gas at flow rate of 0.6 mL·min^-1. As shown by the results, linear relationships between the corresponding response values and mass concentrations of 5 elements were found within 1.00 mg·L^-1, with detection limits (3s) of 0.006-0.201 mg·kg^-1. This method was used to analyze the national standard substances GBW 07142 and GBW 07143 for molybdenum ores, and the determined values were basically consistent with the certified values, with RSDs (n=8) of the determined values less than 8.0%. It was shown by the instrument stability test that it was necessary to replace parts and recalibrate the standard curve in a timely manner when conducting large-scale and long-term tests.