Liquid chromatography assists in the detection of food preservatives



Liquid ChromatographAssisting in the detection of food preservatives isShenzhen Yixin Instrument Equipment Co., LtdProvide.

For the needs of food processing technology and preservation, as well as to improve the quality, color, taste, and aroma of food, small amounts of natural or chemically synthesized substances are usually added to food during the production and processing process. Most preservatives currently used have certain toxicity to the human body, and excessive use can pose a health hazard. Therefore, each country has strict regulations on the amount and residue of preservatives, and accurate detection of preservatives is of great significance for food hygiene and safety.

At present, the detection of food preservatives mainly includes liquid chromatography, gas chromatography, ultraviolet spectrophotometry, thin layer chromatography, titration, etc. Among them, gas chromatographyLiquid ChromatographUV spectrophotometry has high accuracy and fast analysis, and is currently a commonly used detection method.

　　1. Liquid chromatography method

Prepare standard solutions of sodium benzoate, potassium sorbate, and acesulfame, with a detection wavelength of 230nm, and plot standard curves; After ultrasonic degassing and membrane filtration, the sample was directly injected and subjected to chromatographic determination under the above conditions to obtain regression equations and correlation coefficients for various components.Liquid ChromatographThe method has the advantages of fast analysis speed, high separation efficiency, and accurate measurement results, and is a commonly used method for detecting sodium benzoate in food. The commonly used method now is to extract the sample with ethyl alcohol, then dry the extracted sample solution in a water bath, dilute it with methanol, filter it through a membrane, and proceed with the extractionLiquid Chromatographtesting. This experiment uses ultrasonic extraction method, which has the advantages of simple sample pretreatment, easy, fast and accurate operation, and is worth promoting.

　　2. UV spectrophotometry

Using the difference in UV absorption spectra between sodium benzoate and potassium sorbate, multiple linear regression UV spectrophotometry was employed to simultaneously determine sodium benzoate and potassium sorbate in beverages. The samples do not require pre-treatment. The sample does not require pre-treatment, the operation is simple, and multiple components can be measured simultaneously. Good additivity and high accuracy.

　　3. Gas chromatography method

Accurately weigh the sample with an analytical balance and acidify it with hydrochloric acid. Extract and concentrate sorbic acid, benzoic acid, and p-hydroxybenzoic acid lipids with ethyl alcohol. Separate and determine them using a gas chromatograph with a hydrogen flame ionization detector, and compare them quantitatively with the standard. It is relatively simple and sensitive, but the equipment investment cost is high, there are violations of operation, and there are hidden dangers of flammability and explosion.

　　4. Infrared spectroscopy method

Using quantitative accuracy and speed, subtract the infrared spectrum of potassium bromide sodium benzoate from the infrared spectrum of potassium bromide milk powder (taking milk powder as an example) to obtain the characteristic analysis peak (1555cm). Measure the absorbance of the standard solid solution with concentration gradient changes at this wavenumber, and use this absorbance value as the vertical axis and the corresponding concentration as the horizontal axis to draw a working curve. Substitute the absorbance of the test sample into the regression equation to calculate the content of sodium benzoate. The sample pretreatment adopts the method of grinding the sample and potassium bromide in a mortar, drying, and pressing the chip.