双指示剂银量法测定小麦粉皮中氯化物的含量  

Determination of Chloride Content in Wheat Sheet Jelly by Double Indicator Argentometric Titration

作　　者：曾文锦 周丽 陈娟娟 杨雪芬 彭波[2] 王世杰 李婷婷 孙姗姗[3] ZENG Wenjin;ZHOU Li;CHEN Juanjuan;YANG Xuefen;PENG Bo;WANG Shijie;LI Tingting;SUN Shanshan(Food Test Center of Jiuquan,Jiuquan 735000,China;College of Chemistry and Chemical Engineering,Northwest Normal University,Lanzhou 730070,China;National Institute for Food and Drug Control,Key Laboratory of Food Quality and Safety for State Market Regulation,Beijing 100050,China)

机构地区：[1]酒泉市食品检验检测中心,甘肃酒泉735000 [2]西北师范大学化学化工学院,甘肃兰州730070 [3]中国食品药品检定研究院/国家市场监管重点实验室(食品质量与安全),北京100050

出　　处：《食品科技》2024年第2期316-322,共7页Food Science and Technology

基　　金：甘肃省市场监督管理局科技计划项目(SSCJG-SP-A202207);酒泉市科技计划项目(2023CA2014)。

摘　　要：目的:建立双指示剂银量法测定小麦粉皮中氯化物含量的方法。方法:从提取溶剂中乙醇的体积分数、提取温度、提取方式、提取时间、蛋白沉淀剂用量等方面对前处理方法进行优化,以得到最佳的样品提取方法。使用百里香酚酞和铬酸钾双指示剂银量法测定提取溶液中氯离子的含量,通过公式计算得到样品中氯化物的含量。采用智能手机RGB色彩空间取色比较双指示剂银量法和摩尔法滴定终点前后体系的颜色变化敏锐程度。结果:提取溶剂中乙醇的体积分数和提取时间对测定结果影响显著。双指示剂银量法在滴定终点前后体系的颜色变化更敏感,容易判断滴定是否到达终点。10份测试样品中,氯化物的含量在1.30%~3.78%之间,平行测定结果的精密度均小于2.57%。t检验结果证明,该方法与电位滴定法之间无显著性差异。结论:该方法准确性高、可靠性好,前处理过程简单且操作简便,适用于小麦粉皮中氯化物含量的测定。Objective:To establish a method for determination of chloride content in wheat sheet jelly by double indicator argentometric titration.Methods:The pretreatment method was improved by optimizing parameters,including the volume fraction of ethanol in the extract solvent,extraction temperature,extraction method,extraction time,and protein precipitant volume.The content of chloride ion in extract solution was determined by argentometric titration,which used thymolphthalein-potassium chromate as double indicator,and the chloride contents in samples were calculated by formula.The color change sensitivity of system before and after the enf point of the double indicator argentometric titration and the molar method was compared by the RGB color space of the smartphone colorimetric method.Results:The pretreatment conditions,such as the volume fraction of ethanol in the extract solution and extraction time,had significant effects on the determination results.The double indicator argentometric titration method is more sensitive to the color change of the system before and after the titration end point,and it is easy to judge whether the titration reaches the end point.The contents of chloride in 10test samples ranged from 1.30%to 3.78%,and the precisions of parallel determination results being less than 2.57%.The results of t-test indicated that there was no significant difference between double indicator argentometric titration and potential titration method.Conclusion:The established method has high accuracy,good precision,simple pretreatment and easy operation,suitable for determination of chloride in wheat sheet jelly.

关 键 词：双指示剂银量法 小麦粉皮 氯化物 智能手机取色法 RGB色彩空间 

分 类 号：TS207.5[轻工技术与工程—食品科学]