Evaluation of a rapid technique for the determination of precious metals in geological samples based on a selective aqua regia leach

Determination of Pt, Pd, Ru and Ir in geological samples by ID-ICP-MS using sodium peroxide fusion and Te co-precipitation

“…Digestion with aqua regia is rapid and the blank levels are very low, except for samples containing refractory minerals (e.g., chromite), giving low PGE recoveries (Gowing and Potts, 1991). Aqua regia with HF digestion combined with sodium peroxide fusion is an effective method for most geological samples.…”

“…Two main approaches have been used for decomposing samples and pre-concentrating the PGEs. One is nickel sulfide fire assay (Date et al, 1987;Sun et al, 1993;Hall and Pelchat, 1994;Frimpong et al, 1995;Juvonen et al, 1994;Mcdonald et al, 1994;Li and Tong, 1995;Li et al, 1996;Plessen, 1998;Oguri et al, 1999;Sun et al, 2001;Zhou et al, 2001), and the other is aqua regia leach followed by sodium peroxide fusion and Te co-precipitation (Sen Gupta and Gregoire, 1989;Gowing and Potts, 1991;Totland et al, 1995).…”

Reliability of and measurement uncertainty for the determination of Au, Pd, Pt and Rh by ICP-MS in environmentally relevant samples

“…Rh, however, is only completely soluble, if it is available in fmely distributed form. The reactivity of aqua regia is based on the reactivity of the nitrosylchloride (NOCI) and free chlorine (Ch) (Gowing and Potts 1991), which are formed in freshly prepared aqua regia. If sample material is treated in closed vessels under pressure at elevated temperatures with aqua regia, a quantitative leaching can be achieved (Table 3).…”

“…Difficulties related to the determination of the noble metals can include the incomplete recovery after sample preparation or sample digestion (Gowing 1991;Juvonen et al 1994;Nowinski and Hodge 1994) and interferences arising in subsequent instrumental methods (Hall and Pelchat 1993). For this reason the NiSfire assay (Robert et al 1971;Asif and Parry 1990;Reddi et al 1994) and the leaching with aqua regia in closed vessels as sample decomposition methods in combination with inductively coupled plasma mass spectrometry {lCP-MS) are discussed for reliability for the determination of the noble metals in environmentally relevant samples.…”

Isotopic Homogenization of Iridium for High Sensitivity Determination by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

“…One of the popular methods for preconcentration of Ir in geological samples is NiS fire assay method. 12 The inductively coupled plasma (ICP) as an ion source for mass spectrometric detection has been investigated for more than a decade.13 ICP-MS has been well established as a valuable analytical tool and is ideally suited for the measurement at ultra trace levels in both solution samples and solids. Though ETV-ICP-MS is available for direct analysis, the absence of appropriate solid standards prevents accurate determination.…”