小试金光谱法同时测定地质样品中超痕量铂钯金

Simultaneous Spectrographic Determination of Ultra-Trace Pt,Pd and Au in Geological Samples after Enrichment by Minified Fire Assay

用小试金光谱法同时测定地质样品中低至0·x×10^(-9)级Pt、Pd和Au,包括先用小试金熔炼和灰吹预富集10g样品中的Pt、Pd和Au于1mg的银合粒中,然后把银合粒装入石墨电极同锇-锑合金(ω(Os)=0.06)一起激发,以发射光谱法同时测定它们的含量。小试金法类同经典火试金,但采用纯化过的2PbCO_3·Pb(OH)_2(Pt、Pd和Au的含量皆<0.05 ×10^(-9)代替商品PbO,并且用50ml高铝坩埚在950℃进行熔炼。方法的检出限是Pt0.2×10^(-9),Pd和Au均为0.1×10^(-9)。对于3×10^(-9)的含量,全过程的相对标准偏差(％)是Pt15,Pd11,Au9。此法快速、简便,适用于地质物料的分析。

Platinum, palladium and gold at 0.x×10-9 levels in geological samples are determined by minified fire assay-spectrographic method. The method consists of preconcentrating Pt, Pd, and Au from 10 g sample into 1 mg silver bead by minified fire assay and cupellation, and determining the contents with emission spectrometry by aroing the bead in a graphite electrode along with 9 mg osmium-antimony alloy (ω(Os) = 0.06). The minified fire assay has analogy with classical fire assay except using purified lead subcarbonate (Pt, Pd and Au each less than 0.05 × 10-3)instead of litharge and fusing the mixture of sample and flux in a 50 ml alundum crucible at 950℃. Detection limits are 0.1 × 10-9 for Pd and Au, and 0.2 × 10-9 for Pt, overall relative standard deviations (%) for content level of 3×10-9 are 11, 9 and 15 respectively. The method is rapid, simple and applicable to analysis of geological materials.