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1A2-ICP - (1A2-ICP-30 or 50) Au Fire Assay - ICP

Fire Assay

A sample size of 5 to 50 grams can be used but the routine size is 30 g for rock pulps, soils or sediments (exploration samples).   The sample is mixed with fire assay fluxes (borax, soda ash, silica, litharge) and with Ag added as a collector and the mixture is placed in a fire clay crucible, the mixture is preheated at 850°C, intermediate 950 °C and finish 1060 °C, the entire fusion process should last 60 minutes.  The crucibles are then removed from the assay furnace and the molten slag (lighter material) is carefully poured from the crucible into a mould, leaving a lead button at the base of the mould.  The lead button is then placed in a preheated cupel which absorbs the lead when cupelled at 950°C to recover the Ag (doré bead) + Au.



The Ag doré bead is digested in hot (95°C) HNO3  + HCl.  After cooling for 2 hours the sample solution is analyzed for Au by ICP-OES using a Varian 735 ICP. 


Code 1A2-ICP (Fire Assay-ICP-OES) Detection Limits (ppb)


Detection Limit

Upper Limit





Activation Laboratories Ltd. | 41 Bittern Street, Ancaster, Ontario, L9G 4V5, Canada | TF: +1.888.228.5227
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