Determination method for chloride ions of foods

Abstract

The invention relates to a determination method for chloride ions of foods, which belongs to the technical field of food analysis. The method takes a chloride ion selective electrode as an indicator electrode and a two-liquid junction saturated calomel electrode as a reference electrode which are inserted in a sample solution to form a working battery, and when the concentration of chloride ions is in a range of 1 to 10-5g / L, the battery electromotive force is linear with the logarithm of chloride ion activity, and the concentration of the chloride ions of the foods is determined by a digital ion meter. The method of the invention adopts ultrasonic extraction and direct reading concentration method coupling techniques to determine the chlorine content in samples, and the used ultrasonic cleaning device greatly improves extraction speed; and the method has the obvious advantages of difficult sample contamination, low reagent consumption, simpleness and rapidity, accurate and reliable result.

Description

technical field [0001] The invention belongs to the technical field of food analysis, in particular to a method for determining chloride ions in food. Background technique [0002] At present, the determination methods of sodium chloride in food include chemical determination, coulometric analysis and molar titration. Wherein the molar titration method is a national promulgated standard, but this method has the following disadvantages: (1) a white precipitate is generated during the measurement process, and the soy sauce solution is dark red at the same time, which makes it difficult to determine the orange-red end point in the titration process; (2) titration The silver nitrate medicine used is expensive, and the cost is high. The chemical assay is in Fe + In the presence of Hg(SCN) 2 with Cl - The reaction forms and Cl - Equivalent amount of SCN - with Fe 3+ combined into Fe(SCN) 3 The red compound, colorimetric, quantification of Cl in the sample - On the one han...

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Problems solved by technology

Wherein the molar titration method is a national promulgated standard, but this method has the following disadvantages: (1) a white precipitate is generated during the measurement process, and the soy sauce solution is dark red at the same time, which makes it difficult to determine the orange-red end point in the titration process; (2) titration The silver nitrate medicine used is expensive and costly

The chemical assay is in Fe + In the presence of Hg(SCN) 2 with Cl - The reaction forms and Cl - Equivalent amount of SCN - with Fe 3+ combined into Fe(SCN) 3 The red compound, colorimetric, quantification of Cl in the sample - On the one hand, this method is interfered by the color, which makes it difficult to judge the end point. On the other hand, the Hg(SCN) used in the experiment 2 Toxic, harmful to human body

[0003] Coulometry is a physical method. Under a constant current, an Ag electrode is placed in the sample, and the Ag released from the electrode + and Cl - The reaction starts, the generation of AgCl precipitate starts timing, when Cl - All with Ag + After the action is completed, the free Ag + end when it begins to appear, so that the Cl in the sample is determined - content, the disadvantage of this method is that the price of Ag used is high, and it is not easy to popularize and apply

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