自动电位模拟手工滴定法测定粮食脂肪酸值方法研究

通过建立与手工滴定法相关联的自动电位滴定法,研究更为稳定、可靠的脂肪酸值测定方法。按照GB/T 20569-2006《稻谷储存品质判定规则》的规定进行样品前处理,以自动电位滴定代替手工滴定,用氢氧化钾标准溶液滴定样液中的游离脂肪酸,同时测定滴定过程中待测溶液pH的变化,绘制相应的pH-滴定体积实时变化曲线,到达设定的终点pH值即停止滴定,滴定过程以酚酞指示剂监测终点。结果表明,该法滴定过程不受人为因素干扰,准确性与手工滴定法无显著性差异,测定结果具有更好的重复性、再现性和稳定性,适用范围更为广泛。

Study on automatically potentiometric titration simulating manual titration method for determination of fatty acid value of grain

A more stable and reliable method of the fatty acid values determination in grain was studied based on the establishment of manual titration method associated with the automatic potentiometric titration.The GB/T 20569-2006 Guidelines for evaluation of paddy storage character for the sample pre-treatment was used,and the manual titration was replaced by automatic potentiometric titration to determine the free fatty acid in grain with KOH as the standard titration solution.At the same time,the change of pH values in test solution were determined during titration,following by the corresponding real time change curves of pH-titration volume which will be stopped at the set terminal PH values,and phenolphthalein indicator was used as the finish monitoring in the process of the titration.The results showed that the titration processes were not affected by man-made factors,and the accuracy has no significant difference compared with manual titration method,thus ensuring the determination results has better repeatability,reproducibility and stability,and with the wider application scope.