酸碱滴定法测定果蔬中维生素C的可行性

Feasibility of determination of vitamin C in fruits and vegetables by acid-base titration

依据维生素C水溶液呈酸性的性质,利用酸碱滴定法对测定果蔬中维生素C浓度的可行性进行研究.结果表明,当氢氧化钠溶液浓度为0.0100 mol/L,以浓度为0.0025 mol/L的草酸溶液浸提果蔬,以中性红为指示剂,且测定果蔬中不含酸性物质样品时,用酸碱滴定法测定果蔬中维生素C浓度的测定效果很理想.样液不仅无需脱色处理,而且测定方便、成本低,测定结果回收率较好;但对于自身含有酸性物质的果蔬中维生素C浓度的测定结果误差较大,其误差的大小与果蔬自身所含酸性物质的量成正相关,并对此提出了改进建议.

The object was to study the method of determining the content of vitamin C using the acid-base titration in fruits and vegetables,which was based on acidic nature of the vitamin C aqueous solution.The results showed that it would be achieved satisfactory results for determining the content of vitamin C in fruits and vegetables without any acidic substances,usingneutral red as an indicator,when the concentration of sodium hydroxide solution was 0.0100 mol/L,and fruits and vegetables were extracted by 0.0025 mol/L of oxalic acid solution.Not only the decolorization treatment was not necessary for the acid-base titration method,but also there are some advantages,such as convenience,lower cost,stability and better recovery rates.However,the method will have larger error in the determination of vitamin C content in fruits and vegetables containing acidic substances,and the error was positively correlated with the acid content of the fruits and vegetables,furthermore,some suggestions are put forward for improvement in the accuracy of vitamin C content.