碘的阴极溶出伏安法研究

本文研究了碘在悬汞电极上的阴极溶出行为。提出了直接以络合剂(EDTA,DTPA,DCTA)为电解底液便可有效地消除铅、镉、铜等重金属元素的干扰。测定检出限为6.3×10^-9M。方法可不经分离富集直接测定饮用水和食盐中的痕量碘。

STUDIES ON THE CATHODIC STRIPPING VOLTAMMETRY OF IODINE

The cathodic stripping behaviour of iodide films at the hanging mercury drop electrode in a series of electrlytes and the use of complexing agent as masking agent have been investigated. Under the experimental conditions without complexing agent, heavy metal elements showed serirus interference. The interference from less than 1000-fold molar amounts of Zn(II), Cd(II), Pb(II) and less than₂₀₀-fold molar amounts of Cu(II) could be eliminated by the complex formation of those with EDTA, DCTAor DTPA, The optimum condition for the determination of iodide is as f ollowsielec-trolyte 0.02M EDTA (0.01M DCTAor 0.02M DTPA), deposition potential -0.05V (vs. Ag-AgCl), deposition time 2 min., voltage-sweep rate 100mV/sec. Afair reproducibility is obtained in the above procedure and a good proportionality between the peak values of the cathodic stripping current and iodide concentration (10^-6 - 5× 10^-8M) has been observed. The detection limit is 6.3×10^-9M, The recommended method was sucessfully applied to the direct determination of trace iodine in drinking water and common salt. For tap water a mean value of 14.6 ppb I^- was found, while for mineral water the value was 156 ppb I^-, and for the common salt, was 977 ppb I^-. The relative standard deviation for iodine is 3.85%, 3.24%, 1.5% respectively.