|
 Trace level gold analysis begins with a flux mixture of litharge, soda, borax, silica, fluorspar with further oxidants or reductants added as required. The relative concentrations of the fluxing materials are adjusted to suit the type of sample being analyzed. Crucibles are placed into trays of 24 and ~120 grams of flux is added. Twenty samples, two repeats, a standard and a blank are weighed into the crucibles, then placed into a tumbler and mixed for 10 minutes. When mixed, the samples are removed, inquarted and fused. The resultant lead button is then cupelled. After cupellation the Doré bead is dissolved in aqua regia and analyzed by Atomic Absorption Spectrometry. Gold values >1000 ppb are routinely analyzed by FA/Gravimetric.
Gravimetric
gold analysis begins with a flux mixture of litharge, soda, borax, silica, fluorspar
with further oxidants or reductants added as required. The relative concentrations
of the fluxing materials are adjusted to suit the type of sample being analyzed.
Crucibles are placed into trays of 24 and ~120 grams of flux is added. Twenty
samples, three repeats and a standard are weighed into the crucibles, then placed
into a tumbler and mixed for 10 minutes. When mixed, the samples are removed,
inquarted and fused. The resultant lead button is then cupelled. After cupellation
the subsequent Doré bead is flattened, placed in a porcelain cup and parted with
a dilute nitric acid solution. The gold obtained is decanted with de-ionized water,
dried, annealed, and weighed on a microbalance.
Platinum
and palladium analyses parallel the trace level gold procedure. |
 |
