pH计电位滴定法测定鸭梨醋中总酸的不确定度评定  

Evaluation of Uncertainty of Total Acid in Yapear Vinegar by pH Meter Potentiometric Titration Method

作　　者：吴珍珍 杨振东 高牡丹 鲍连艳 胡明燕 于艳艳 WU Zhenzhen;YANG Zhendong;GAO Mudan;BAO Lianyan;HU Mingyan;YU Yanyan(Shandong Inspection and Research Institute for Food and Drug,Jinan 250101,China;Key Laboratory of Supervising Technology for Meat and Meat Products for State Market Regulation,Jinan 250101,China)

机构地区：[1]山东省食品药品检验研究院,山东济南250101 [2]国家市场监管重点实验室(肉及肉制品监管技术),山东济南250101

出　　处：《食品安全导刊》2022年第29期108-111,共4页China Food Safety Magazine

摘　　要：目的:通过鸭梨醋中总酸的含量测定实验进行不确定度评定,建立pH计电位滴定法测定鸭梨醋中总酸方法不确定度方法。方法:采用pH计电位滴定法,以氢氧化钠标准滴定溶液为滴定剂,pH 8.2为滴定终点,进行酸碱中和滴定反应。通过数学模型确定不确定度来源,评定实验各因素带入的不确定度,建立p H计电位滴定法测定鸭梨醋中总酸含量不确定度评价方法。结果:合成相对标准不确定度为0.002 79,扩展不确定度为0.02 g/100 mL,鸭梨醋中总酸的测定结果为(3.30±0.02)g/100 mL,不确定度主要来源是重复性实验产生的不确定度,其次是滴定产生的不确定度。结论:鸭梨醋中总酸的测定结果不符合《食品安全国家标准食醋》(GB 2719—2018)对食醋中总酸含量≥3.5 g/100 mL的要求,检验结论为不合格。Objective: By evaluating the uncertainty of the content of total acid in Yali vinegar, a pH meter potentiometric titration method was established to determine the uncertainty of the total acid in Yali vinegar. Method:Adopt the pH meter potentiometric titration method, Using sodium hydroxide standard titration solution as titrant,pH meter 8.2 as the end point of the titration. The source of uncertainty was determined by mathematical model, and uncertainty brought by various factors in the experiment was evaluated. The pH meter potentiometric titration method was established to determine the uncertainty of total acid in pear vinegar. Result: The synthetic relative standard uncertainty is 0.002 79, the expanded uncertainty is 0.02 g/100 mL, and the total acid in Yali vinegar is(3.30±0.02) g/100 mL. The main source of uncertainty is the uncertainty generated by repeated experiments, the second is the uncertainty created by the titration. Conclusion: The determination results of total acid in pear vinegar did not meet the requirements of GB 2719—2018 for total acid in vinegar greater than or equal to 3.5 g/100 mL, and the inspection conclusion was unqualified.

关 键 词：食醋 总酸 pH计电位滴定法 不确定度 

分 类 号：O657.1[理学—分析化学] TS264.22[理学—化学]