在pH5.0邻苯二甲酸氢钾-氢氧化钠介质中,痕量铜具有明显催化高碘酸钾氧化3-间氯基苯基-5-(4′-甲基-2′-磺酸酸基苯偶氮)若丹宁的作用,由此建立了催化动力学荧光法测定痕量铜的新方法。该体系的激发和发射波长(λex和λem)分别为310 nm和404 nm。通过实验测定反应表观活化能为165.06 kJ/mol,反应速率常数为0.47/s,线性范围为0.45~12.0μg/L,检出限为1.5×10^-7g/L。采用巯基葡聚糖凝胶分离富集,消除了共存离子的干扰,显著提高了方法的选择性和灵敏度。该方法应用于喷泉水、人工湖水和管网水中铜的测定,相对标准偏差小于4.5%,测定结果与原子吸收光谱法测得的结果相符。
A new catalytic fluorescent method was established for the determination of trace copper.The method was based on the catalytic effect of copper on the oxidation of 3-(3'-chlorophenyl)-5-(4'-methyl-2'-sulfonophenylazo) rhodanine by potassium periodate in potassium hydrogen phthalate-sodium hydroxide medium(pH=5.0).The excitation wavelength(λex) and emission wavelength(λem) were 310 nm and 404 nm,respectively.The apparent active energy of reaction was 165.06 kJ/mol.The reaction rate constant was 0.47/s.The linear range was 0.45-12.0 μg/L,and the detection limit was 1.5×10^-7 g/L.The interference of coexisting ions was eliminated by separation and enrichment with sulfhydryl dextrane gel(SDG),and the selectivity and sensitivity of this method were significantly improved.The proposed method has been successfully applied to the determination of trace copper in spring water,artificial lake water and tap water samples.The relative standard deviation(RSD) was smaller than 4.5 %,and the determination results were in good agreement with those obtained by atomic Absorption spectrometry.