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报道一个新的光度法测定铜.在聚乙烯醇存在下铜钨杂多酸络阴离子与罗丹明 B(RB)阳离子形成离子缔合物,在0.96mol/L 硫酸介质中缔合物的最大吸收位于570nm,表观摩尔吸光系数ε=1.53×10~6,铜量在0～0.5μg/25ml 范围内服从比尔定律,测定下限0.36ng/ml(n=12),对0.018μg/ml 铜测定11次的相对标准偏差为0.83%.缔合物至少稳定240h,缔合物的摩尔组成为 Cu:w:RB=1:12:5.考察了40多种共存离子的影响,大多数常见离子不干扰.本法已用于天然水、自来水、降水、人发、中药和蔬菜中铜的测定,结果满意.
A new spectrophotometric method for the determination of copper was reported.The maximum absorption of the complex in the 0.96 mol / L sulfuric acid medium was achieved by the formation of ion-association of the copper-tungsten heteropoly acid complex anion with rhodamine B (RB) cation in the presence of polyvinyl alcohol At 570nm, the apparent molar absorptivity ε = 1.53 × 10 ~ 6, Beer’s law was obeyed in the range of 0 ~ 0.5μg / 25ml, the lower limit of determination was 0.36ng / ml (n = 12) The relative standard deviation of 11 times was 0.83%. The association was stable for at least 240 h, and the molar composition of association was Cu: w: RB = 1: 12: 5. The effects of more than 40 kinds of coexisting ions were examined. This method has been applied to the determination of copper in natural water, tap water, precipitation, human hair, Chinese medicine and vegetables with satisfactory results.