原子吸收光谱法测定贵金属合金中的铬

Determination of Chromium in Precious Metal-based Alloys by Atomic Absorption Spectrometry

采用原子吸收光谱法测定CoCrPtSiO2、AuNiCr、NiPdCrBSi、NiCrB 合金中铬含量,研究了影响铬测定的因素及其消除条件.结果表明,用盐酸-硝酸、氢氟酸密闭消解样品,高氯酸发烟驱除剩余氢氟酸,氯化铵或水合肼消除大量镍（II）、硅（IV）或金（III）的影响,用亚硫酸钠转化可将铬（VI）完全转化为高灵敏度的铬（III）;标准曲线线性范围0-6.00 μg/mL,检出限0.004 μg/mL;测定含量为5%-7%的铬,相对标准偏差0.82%-1.29%,加标回收率为93.34%-110.80%.

Chromium contents in CoCrPtSiO2, AuNiCr, NiPdCrBSi, NiCrB alloy were determined by using atomic absorption spectrometry, the interference from other elements in the determination was investigated and the eliminating method was given. After the sample is transferred into the aqueous solution with a mixture of hydrochloric acid, nitric acid and hydrofluoric acid, the remaining hydrofluoric acid in the sample is dispelled by using perchloric acid. And then Ni(II) and Si(IV) are removed by precipitation with ammonium chloride, whereas Au(III) is removed by reduction with hydrazine hydrate. The conversion of Cr(VI) into Cr (III) gives rise to a final solution which will be submitted for AAS measurements. The standard working curve is linear in the range of 0~6.00 μg/mL with a detecting limit of 0.004 μg/mL. When chromium content is between 5%to 7%in the samples, the relative standard deviation can be less than 1.29%. The recovery for standard addition ranges from 93.34%to110.80%.