Acid quality: Perform validation tests on new HCL and HNO3 acid purchases by performing six sample digestions without prills and analyzing by ICP-OES. The results should be 0.001 ppm or lower.
Equipment: Hot plate temperature is measured with an approved thermometer and verified before sample digestion. Acid dispensers are checked daily by dispensing every 5 times and comparing the dispensed weights to the calculated target weights. The 8 ml bulking dispenser must be within 0.5% of the target weight, and the other dispensers within 2%.
Fire assay cupels’ copper stain indicators are compared to the fire assay worksheets for accuracy. Any deviations are documented and noted in LIMS. For quality control, the copper checking process will not be performed by the fire assay department—it must be done by the digestion techs. When paperwork properly reflects cupel staining, sample sequences are correct through the fire assay process. Prills in racks of 42 will be transferred to the 60-position test tube racks. The digester will complete a rack form for each rack that indicates the jobs and samples contained therein.