不镀汞膜电位溶出分析法用于皮蛋中微量铜的测定

A STUDY ON ASSAY OF MICRO AMOUNTS OF COPPER IN PRESERVED EGG BY MEANS OF PSA WITH GLASSY CARBON ELECTRODE WITHOUT PRECOATING OF MERCURY FILM

用不镀汞瞋电位溶出分析法,测定皮蛋中微量铜。通过筛选试验,确定其适宜条件为:pH 1.5～2.5、2×10^(-2)mol/L KNO_3、2×10^(-3)mol/L NaCl和2×10^(-3)mol/L KI为介质。避光,以溶解氧为氧化剂,在-0.8 V(V.S Ag/AgCl)富集5 min,动态溶出,用标准加入法定量。用本法测定皮蛋中微量铜的结果与原子吸收光谱法和常规电位溶出法测定结果相吻合。本法回收率为97.3％-100.6％。最低检出限为2×10^(-10)mol/L。

In this paper, determination of copper in preserved egg by means of potentiometric stripping analysis(PSA), glassy carbon electrode without film mercury as working electrode, was discussed. Under the optimum conditions: 2×10^(-3) mol/L NaCl, 2×10^(-2) mol/L KNO_3, 2×10^(-3) mol/L KI, pH=2.0 and E_d=-0. SV(VS.Ag/AgCl) copper can be directly deposited on a glassy carbon electrode, and then oxidized by dissolved oxygen. The stripping curve was thus recorded. The detectable limit for Cu^(2+) was 2×10^(-10) mol/L and recovery percent was 97.3％ to 100.6％, The results agree satisfactorily with those obtained by AAS and Normal PSA.