Determination of Chloride Content in Wheat Sheet Jelly by Double Indicator Argentometric Titration
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 10 test 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.
double indicator argentometric titrationwheat sheet jellychloride contentsmartphone colorimetric methodRGB space
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