リン化白金中のリン及び白金定量のための濃硫酸又は溶融二硫酸ナトリウム中加熱/塩酸-硝酸の混酸による溶解  [in Japanese] Dissolution of Platinum Phosphide in a Mixture of Hydrochloric Acid and Nitric Acid after Heating in Concentrated Sulfuric Acid or Melted Sodium Disulfate for Determination of Platinum and Phosphorus  [in Japanese]

リン化白金(2種類の無機化合物PtP_2及びPt_5P_2から成る試料,金属様光沢を有す)は耐酸性であり,王水を含む酸類には溶解しなかった.しかし,濃硫酸又は溶融二硫酸ナトリウム中で十分加熱した後,塩酸-硝酸の混酸で容易に溶解した.その溶解は次のように2段階で進むことが分かった.まず,リン化白金を濃硫酸又は溶融二硫酸ナトリウム中で加熱することによってリンの大部分が試料から選択的に溶出する.一方,白金は大部分が試料形状を保った状態で溶解せずに残る.したがって,白金だけになった試料は塩酸-硝酸の混酸によって容易に溶解する.つまり,二元系無機化合物であるリン化白金から一方の元素(リン)だけが選択的に溶解する現象が見られた.溶解によって得られた溶液中のリン及び白金を誘導結合プラズマ発光分光分析法で分析した結果,これら元素は試料溶解時に損失することなく定量できた.

A platinum phosphide sample was constituted of PtP_2 and Pt_5P_2 which were determined by X-ray diffraction. It had the shape of a thin plate (thickness of about 0.5mm), and had a platinum-like color. It was not dissolved in aqua regia and other acids, because it was an acid-resistant substance. However, it could be dissolved in a mixture of hydrochloric and nitric acids, after it was heated sufficiently in concentrated sulfuric acid or melted sodium disulfate. Most of the phosphorus was first of all extracted from the phosphide by heat in concentrated sulfuric acid or melted sodium disulfate. On the other hand, most of the platinum remained in it, and the shape of the thin plate virtually remained the same. The platinum was dissolved in a mixture of hydrochloric and nitric acids. Platinum and phosphorus in the phosphide were determined by ICP optical emission spectrometry (ICP-OES) without their loss during dissolution.