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本文报导利用形成六氰合铁(Ⅲ)酸亚铁钾深蓝色配合物进行吸光光度法测定啤酒花中单宁的适宜条件及测定方法。实验结果表明:在pH2.5～3.0的盐酸介质中,六氰合铁(Ⅲ)酸亚铁钾配合物的最大吸收波长在760nm;于760nm处,六氰合铁(Ⅲ)酸亚铁钾的摩尔吸光系数为7.4×10~5l·mol~(-1)·cm~(-1);单宁浓度在0.1～1.6μg·ml~(-1)范围内遵守Beer定律:回收率在95.67～104.00%之间;多次平行测定的变动系数为1.5%。六氰合铁(Ⅲ)酸亚铁钾吸光光度法测定啤酒花中单宁的含量,方法灵敏、简便、准确度和精密度较好。
In this paper, the suitable conditions for the determination of tannin in hops by spectrophotometry using ferrous potassium hexacyanoferrate (Ⅲ) and its dark blue complex were reported in this paper. The experimental results showed that the maximum absorption wavelength of ferrous iron hexacyanoferrate (Ⅲ) was at 760 nm in hydrochloric acid solution of pH 2.5-3.0. At 760 nm, ferrous hexacyanoferrate The molar absorptivity was 7.4 × 10 ~ 5l · mol ~ (-1) · cm ~ (-1). Beer ’s law was obeyed in the range of 0.1 ~ 1.6μg · ml ~ (-1) with the tannin concentration: the recovery was 95.67 ~ 104.00%; the coefficient of variation of multiple parallel determination was 1.5%. Determination of tannin content in hops by potassium ferricyanide (Ⅲ) ferrous potassium absorption spectrophotometry. The method is sensitive, simple, accurate and precise.