高锰酸钾滴定法快速测定蔬菜中抗坏血酸含量

Rapid Determination of Ascorbic Acid in Vegetable by Potassium Permanganate Titrimetry

研究快速测定蔬菜中抗坏血酸含量的高锰酸钾滴定新方法。基于KMnO4能在室温条件下定量地将抗坏血酸氧化为脱氢抗坏血酸,可在试样被偏磷酸提取后的酸性溶液中,用EDTA掩蔽干扰离子后,直接用KMnO4标准溶液滴定试液中的抗坏血酸,并利用KMnO4自身的颜色变化而指示滴定终点。测定结果的相对标准偏差小于1.0%,加标回收率在93.8%～101.2%之间。结果表明,改进后的方法操作简便,测定快捷,干扰小,测定结果与国家标准方法相符,相对偏差均小于2.5%。

A new rapid determination method of ascorbic acid content in vegetable by potassium permanganate titrimetry was studied. Based on KMnO4 quantitatively oxidating ascorbic acid to dehydro-ascorbic acid at room temperature, after masking interfering ions, the metaphosphori extraction solution of sample can be titrated with KMnO4 standard solution directly to determine ascorbic acid content according to color change. The method was applied for the determination of ascorbic acid in vegetable with the relative standard deviation of less than 1.0% and the recoveries of standard addition of 93.8 %- 101.2 %. It has the characteristics of easy operation, fast determination and little disturbance. The determination results are consistent with those by China national standard method with both relative deviations of less than 2.5 %.