title: Determination of platinum, palladium and silver in geological materials and their concentrates by fire assay and emission spectrography.
abstract: A method is described for the determination of platinum down to 10 ng, palladium to 5 ng and silver to 10 pg in 50 or 100 g of sample. Fire-assay techniques are used to preconcentrate these metals into a bead which is first treated with nitric acid to dissolve palladium and silver and then with aqua regia to dissolve platinum. Both solutions are diluted and adjusted to pH 4, then analysed by optical emission spectrography of the residue from a measured volume evaporated on a pair of flat-top graphite electrodes. This method requires much less sample handling than most published methods for these elements.
authors.affiliation: Faculty of Chemistry State University of Sofia 1 Anton Ivanov Avenue Sofia 26, Bulgaria.
authors.forename: E G
authors.initials: EG
authors.lastname: Koleva
authors.forename: S H
authors.initials: SH
authors.lastname: Arpadjian