Verma K K, Gupta D, Sanghi S K, Jain A
Department of Chemistry, Rani Durgavati University Jabalpur 482 001, Madhya Pradesh, India.
Talanta. 1988 Nov;35(11):917-9. doi: 10.1016/0039-9140(88)80215-7.
A quick anion-exchange reaction, suitable for the determination of sulphide, has been found to occur on stirring a suspension of lead iodate (solubility product, K(s0) = 1.2 x 10(-13)) with sulphide solution at pH 5-8. After removal of the precipitates of lead iodate and lead sulphide (K(s0) = 3.4 x 10(-28)), the iodate released can be determined by its reaction with acidified iodide to give tri-iodide which is either titrated with thiosulphate or measured spectrophotometrically as its blue complex with starch. Chloride, bromide, iodide, fluoride, oxalate, sulphate, thiocyanate and phosphate do not interfere. Thiosulphate, sulphite, nitrite and thiols do not give an anion-exchange reaction but do interfere in the redox reaction of iodate with acidified iodide. However, this is avoided if they are first oxidized with bromine (the liberated iodate remains unaffected before iodometry.
已发现，在pH值为5 - 8的条件下，将碘酸铅悬浮液（溶度积K(s0) = 1.2×10⁻¹³）与硫化物溶液搅拌时，会发生一种适用于测定硫化物的快速阴离子交换反应。除去碘酸铅和硫化铅沉淀（K(s0) = 3.4×10⁻²⁸）后，释放出的碘酸盐可通过其与酸化碘化物反应生成三碘化物来测定，三碘化物可用硫代硫酸盐滴定，或作为其与淀粉的蓝色络合物进行分光光度测定。氯离子、溴离子、碘离子、氟离子、草酸盐、硫酸盐、硫氰酸盐和磷酸盐不产生干扰。硫代硫酸盐、亚硫酸盐、亚硝酸盐和硫醇不会发生阴离子交换反应，但会干扰碘酸盐与酸化碘化物的氧化还原反应。然而，如果先将它们用溴氧化，就可以避免这种干扰（在碘量法之前，释放出的碘酸盐不受影响）。
