Method for quantitatively detecting thiocyanate in milk and milk products

Abstract

The invention provides a method for quantitatively detecting thiocyanate in milk and milk products. The method is used for quantitatively determining content of thiocyanate in milk and milk products by spectrophotometry. The method is simple to operate, relatively low in detection limit, short in detection time, high in accuracy, good in reproducibility, relatively high in recovery rate and suitable for fast detection of thiocyanate. The method comprises the following steps: (1) processing a sample; and (2) detecting the sample, wherein reagents used by the method comprise a sodium thiocyanate reagent A, a sodium thiocyanate reagent B, a sodium thiocyanate reagent C and a sodium thiocyanate reagent D; the sodium thiocyanate A is an acetic acid solution, and a volume ratio of water to acetic acid in the acetic acid solution is 10 to 50; the sodium thiocyanate reagent B is an anhydrous di-potassium hydrogen phosphate solution with a mass fraction of 5%-30%; the sodium thiocyanate reagent C is a chloramines T solution with a mass fraction of 1%-10%; the sodium thiocyanate reagent D is a mixed solution of isonicotinic acid with a mass fraction of 1%-10%, barbituric acid with a mass fraction of 1%-5% and sodium hydroxide with a mass fraction of 1%-10%.

Description

technical field [0001] The invention relates to a method for quantitatively detecting thiocyanate in milk and dairy products. Background technique [0002] Thiocyanate is a chemical raw material often used in various industries such as medicine, printing and dyeing, and is generally white crystal or powder. Adding an appropriate amount of thiocyanate to milk can effectively inhibit bacteria, keep fresh and prolong the shelf life of milk. It is usually added in the form of sodium thiocyanate in food. In 2008, the Ministry of Health issued the "List of Non-edible Substances and Food Additives That May Be Added Illegally in Food (the first batch)" clearly stipulating that sodium thiocyanate in milk and dairy products is an illegally added substance. [0003] At present, there is no national standard or industry standard for the detection of sodium thiocyanate in food. The main methods of determination include ion chromatography, capillary electrophoresis, spectrophotometry, an...

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Problems solved by technology

The Food Remediation Office of the Ministry of Health [2009] No. 29 "Notice on Printing and Distributing the Guiding Principles and Plans for Special Rectification and Sampling of the National Crackdown on Illegal Addition of Non-edible Substances and Abuse of Food Additives" recommended that "determination of thiocyanate in milk by ion chromatography" be used as Reference method, but when ion chromatography detects the content of sodium thiocyanate, the pretreatment of the sample is more complicated and the detection time is longer; capillary electrophoresis saves solvent, and the separation mode is diversified, which can be modified by the modification method of the inner wall of the capillary and the flowing buffer The different additives in the method can improve the separation effect and other functions; however, the ion chromatograph and capillary electrophoresis instrument are expensive, and both require professional technicians to operate, which is not conducive to the use and promotion in small enterprises, and is not easy to carry and do. Rapid detection; spectrophotometric method mostly adopts ferric ammonium sulfate method or isonicotinic acid-pyrazolone method, the detection limit of these two methods is high, and the accuracy is low for low concentration thiocyanate; milk and milk The product contains various nutrients such as amino acids, proteins, fats, etc., and the matrix is ​​relatively complex, which has a great impact on the test results, so it is not suitable for determination by potentiometric titration

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