Bismuth-Remaining Cupellation Fire Assay Preconcentration Combined with Inductively Coupled Plasma Mass Spectrometry for the Simultaneous Determination of Ultratrace Au, Pt, Pd, Ru, Rh, and Ir in Geologic Samples

Table 2

Bismuth fire assay recipes for geochemical samples.

Sample type	Recipe (g)
	Sample weight	Na2B4O7·10H2O	Glass powder	Na2CO3	Bi2O3	Flour	KNO3
Silicate rock	10–20	15	15	55	40	4	—
Carbonate rock	10–20	15	20	50	40	4	—
Sulfide rock	10–20	15	20	50	40	4.5	—
Soil	10–20	15	15	55	40	4	—
Stream sediment	10–20	15	15	55	40	4	—
Black shale	10	20	20	50	80	7	5
Polymetallic ore	10	15	20	50	100	5	—
Chromite	—	25	20	30	40	6	—

Sample was placed into the furnace maintained at 600°C for 2 hours.