Determination of trace phosphorus in high purity tantalum materials by inductively coupled plasma mass spectrometry subsequent to matrix separation with on-line anion exchange/coprecipitation
2002
Kozono, Shuji | Takahashi, Shigeto | Haraguchi, Hiroki
An on-line matrix separation/inductively coupled plasma mass spectrometry (ICP-MS) method is proposed for the determination of trace amounts of phosphorus in high purity tantalum metal, tantalum (V) oxide, and tantalum pentaethoxide. In the present method, the matrix tantalum in the sample solution was adsorbed on the anion exchange resin, and phosphorus (phosphate ion) was eluted with the carrier solution of HF and HNO₃mixture. Then, the effluent solution was subsequently mixed with bismuth solution and aqueous ammonia solution to coprecipitate phosphate together with bismuth hydroxide. The precipitate formed was collected on the in-line membrane filter to wash out nitric acid with pure water, and then dissolved with hydrochloric acid. The obtained phosphorus sample solution was introduced directly into the nebulizer of ICP-MS for the determination of phosphorus. Phosphorus was determined at the molecular ion signal of³¹P¹⁶O⁺(m/z 47). The detection limit (3σ) of phosphorus in the present method was 1.3 ng mL–¹as the sample solution basis, and the relative standard deviation for 30 ng mL–¹of phosphorus in the standard solution was 4.3% in the replicate measurements (n=11). The present method was applied to the analysis of high purity tantalum materials. The concentrations of phosphorus in tantalum samples were in fairly good agreement with those obtained by glow discharge mass spectrometry (GDMS).
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