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根据次亚磷酸钠在硝酸介质中能将两价铜还原为金属铜,而镍不被还原的性质,使铜与镍快速分离。这样,便可直接取澄清液用自制的75—4B型快速极谱仪(见化学通报1981年11期33页),就铜合金中镍在汞膜电极上的导数极谱催化波进行测定。本文应用氯化铵—氢氧化铵为缓冲溶液,在pH9左右,先以亚硫酸钠除氧,然后再加丁二酮肟使之与镍络合,在-0.1伏至-1.15伏之间(对大面积银汞电极)测定其导数催化波,镍的测定下限可达2×10~(-9)克/毫升,其浓度在10~(-7)～10~(-9)克/毫升范围内与导数极谱电流呈良好的线性关系,在铜合金测定中,使用试剂少,灵敏度高,分析快速,与标样对照相符。方法相对偏差在10%以内。
According to the hypophosphite in the nitric acid medium can be reduced to two metallic copper copper, nickel is not the nature of the reduction, the rapid separation of copper and nickel. In this way, the direct precipitation of the supernatant can be determined using a self-made 75-4B rapid polarimeter (see Chemistry Bulletin, 1981, p. 33) for the catalytic polarographic derivatization of nickel on the mercury film electrode in copper alloys. In this paper, ammonium chloride - ammonium hydroxide buffer solution at pH9 or so, with sodium sulfite deoxygenation, and then with dimethylglyoxime so that it is complexed with nickel, between -0.1 volts to -1.15 volts (large Area silver mercury electrode), the lower limit of determination of nickel was up to 2 × 10 -9 g / ml, and its concentration ranged from 10 -7 to 10 -9 g / ml And the derivative of the polarographic current showed a good linear relationship in the determination of copper alloys, the use of reagents, high sensitivity, fast analysis, and the standard control line. The relative deviation of the method is within 10%.