增敏光度法测定粮食中微量碘

Determination of trace iodine in grain by sensitizing spectrophotometry

研究了NaCl增敏碘 淀粉显色反应。NaCl用量为0 24g mL,H3PO4(3+97)为0.5mL的酸度条件下以KI还原KIO3与淀粉显色,λmax=483nm,λmax=2 7×105L·mol-1·cm-1。在483nm处,测得碘在大米、小麦和玉米中的回收率在96.3%～99.1%,RSD<2.5%。该法已用于大米、小麦、玉米等食品中微量碘的分析。

Color reactions of iodine and starch sensitized by sodium chloride were studied. Potassium iodate was reduced into iodine by potassium iodide, and then reacted with starch in 25 mL of solution containing 6 g of sodium chloride and 0.5 mL of (3+97) phosphoric acid at λ_(max)=483 nm, λ_(max)=2.7×10~5 L·mol^(-1)·cm^(-1). Recoveries of iodine in rice, wheat and maize determined at 483 nm were in the range of 96.3% to 99.1%. Relative standard deviations were less than 2.5%. The method was used in determination of trace iodine in rice, wheat and maize with satisfactory results.