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本文提出以铍试剂Ⅱ作镁的显色剂,它在 PH11.7～12.3的氨性溶液中与镁形成最大吸收位于620毫微米的兰色络合物,络合物组成为 Mg:R=1:1,摩尔吸光系数等于1.1×10~4。显色反应具有较高的选择性,500微克的锰(Ⅱ)、铬(Ⅲ),400微克的镍,200微克的钼(Ⅵ)、钒(Ⅴ),钛(Ⅳ)、锌(Ⅱ)铈(Ⅲ)、铋(Ⅲ)、铅(Ⅱ)、砷(Ⅴ),100微克的钙(Ⅱ)、铬(Ⅲ)、钻(Ⅲ)不干扰20微克镁的测定。三乙醇胺可掩蔽大量铁(Ⅲ)和铝(Ⅲ),因而可以不经分离而直接测定球墨铸铁和某些铝合金中的镁,方法简便快速,有较高的准确度和重现性。
In this paper, beryllium reagent Ⅱ is used as chromogenic reagent of magnesium, which forms the blue complex with magnesium in the ammoniacal solution of PH11.7 ~ 12.3 with maximum absorption at 620 nm. The complex has the composition of Mg: R = 1: 1, the molar absorption coefficient is equal to 1.1 × 10 ~ 4. The chromogenic reaction is highly selective. With 500 micrograms of manganese (Ⅱ), chromium (Ⅲ), 400 micrograms of nickel, 200 micrograms of molybdenum (Ⅵ), vanadium (Ⅴ), titanium (Ⅳ) The determination of 20 micrograms of magnesium did not interfere with cerium (Ⅲ), bismuth (Ⅲ), lead (Ⅱ), arsenic (Ⅴ), 100 μg of calcium (Ⅱ), chromium (Ⅲ) Triethanolamine masks a large amount of iron (III) and aluminum (III) and therefore allows direct determination of magnesium in nodular cast iron and some aluminum alloys without isolation. The method is simple and fast with high accuracy and reproducibility.