A green titrimetric method using potentiometry is proposed for determination of the acid number of vegetable oils and animal fats. The sample is dissolved in a water-ethanol mixture (1:1 v/v) and potentiometrically titrated with a 0.02 mol L-1 aqueous NaOH standardized solution using a glass pH combined electrode. Canola, sunflower, linseed, castor, corn and soy oils as well as swine lard, a total of twelve real samples, were analyzed. The results were compared with those from the application of the procedures AOCS Cd 3d-63 and ABNT-NBR 14448 and a green visual titrimetric method, through a statistical linear regression procedure at the 95% confidence level. No evidence for systematic differences was observed. Mean relative standard deviation for the proposed procedure was 2.7%, whereas that for the AOCS and ABNT methods 5.4% and for the visual green method 4.8%.
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机译：提出了一种使用电位滴定法的绿色滴定法测定植物油和动物脂肪的酸值。将样品溶解在水-乙醇混合物（1：1 v / v）中，并使用玻璃pH混合电极用0.02 mol L-1 NaOH标准化水溶液进行电位滴定。总共分析了十二种油菜籽，菜籽油，向日葵油，亚麻籽油，蓖麻油，玉米和大豆油以及猪油。通过统计线性回归程序（在95％置信水平下），将结果与应用AOCS Cd 3d-63和ABNT-NBR 14448方法以及绿色视觉滴定法的结果进行了比较。没有观察到系统差异的证据。拟议程序的平均相对标准偏差为2.7％，而AOCS和ABNT方法的平均相对标准偏差为5.4％，视觉绿色方法的平均相对标准偏差为4.8％。
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