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本文研究了偶氮胂DBS与钙的显色反应,拟定了锰矿中钙的分析条件。在HCl-Na_2CO_3缓冲溶液中(pH10),偶氮胂DBS与钙生成红色络合物,于610nm处有最大吸收,桑德尔灵敏度可达0.002μgCa/cm~2,0—16μgCa/25mL符合比尔定律。在拟定条件下,基体锰的干扰可在氨水介质中加过氧化氢将锰(Ⅱ)氧化成水合二氧化锰而与铁、铝的氢氧化物一同沉淀析出,从而与钙、镁等分离;继而调至pH>12,使镁以氢氧化物沉淀析出而与钙分离。方法简便,稳定性好,用于测定冶金工业部含钙的锰矿标准试样,结果与推荐值一致。
In this paper, the color reaction of arsenazo DBS with calcium was studied and the analytical conditions of calcium in manganese ore were established. In HCl-Na 2 CO 3 buffer solution (pH 10), arsenazo DBS complexed with calcium and had a maximum absorption at 610 nm with a sensitivity of 0.002 μgCa / cm ~ 2.0-16 μgCa / 25 mL according to Beer’s law . Under the proposed conditions, the interference of matrix manganese can be oxidized with ammonia and aqueous medium to oxidize manganese (II) into hydrated manganese dioxide and precipitated together with iron and aluminum hydroxides to separate from calcium and magnesium. Then adjusted to pH> 12, the precipitation of magnesium precipitated with calcium and calcium separation. The method is simple and has good stability, and is used for determining the standard manganese sample containing calcium in the Ministry of Metallurgical Industry. The result is consistent with the recommended value.