可见光谱法直接测定油脂碘值

Direct measurement of oil iodine value through visible spectrometry

油脂与韦氏液发生加成反应后,加入碘化钾溶液,析出的碘以50%冰醋酸的水溶液作参比,在630 nm处测定碘吸光度值Ae,同时作空白,测定其A0,间接找到油脂消耗氯化碘的量,其消耗的量与油脂碘值成正比,由此可以计算出油脂的碘值。结果表明,与韦氏法比较,结果基本相同,相对误差小于2%。

After completion of addition reaction between oil and Wijs solution,potassium iodide was added into the solution. The 50%acetic acid aqueous solution was set as reference to the yield iodine, then the absorbance values Ac of iodide was measured at the point of 630 nm. Meanwhile,the value A0 was evaluated through reagent blank. The consumption of oil reacted with iodine chloride was indirectly determined. The results indicate that the consumption of oil was proportional to the amount of oil IV, the oil IV was then determined. The outcomes also show that the value was approximately the same as that measure by Wij’s method. The relative error was less than 2%by visible spectrometry.