1. Gas chromatography method
This detection method is mainly used to determine substances that vaporize but do not decompose. For substances that are difficult to gasify or unstable, they are generally determined through chemical derivatization methods. This method is mainly used to detect ester and acid preservatives in food. Generally, the sample needs to be acidified with reagents such as sulfuric acid or hydrochloric acid to convert the additive from an ionic state to an organic molecular state. Finally, low performance solvents such as ether and petroleum ether are used for extraction. Due to the low volatility of sweeteners, gas phase chromatography is not widely used in their applications. The treatment of sweeteners generally involves derivatization first, and then gas chromatography can be used for detection.
Experiments have shown that when determining the content of saccharin using capillary gas chromatography, after reacting sodium nitrite with sulfuric acid medium in the detection sample, the NaOH alkaline solution is processed. Taking cyclohexanol as an example, the external standard method is used to extract the content of cyclohexanol. Furthermore, the quantification of saccharin was achieved. After fully dissolving the alkaline solution with water. It can effectively reduce the interference of saccharin. This method is generally applicable to the detection of honey money, wine samples, and various foods.
Gas chromatography-tandem mass spectrometry
In recent years, the high sensitivity of mass spectrometry detectors and the high separation ability of gas chromatography have complemented each other, making gas chromatography tandem mass spectrometry the most rapidly developing analytical method. With the continuous improvement of supercritical extraction and solid-phase extraction technologies, the application of gas chromatography-mass spectrometry technology in additive detection is also increasing. For example, by thermally decomposing aspartame from 350 ℃ to 950 ℃ and using an ion trap detection mass spectrometer to detect and obtain a peak, the presence of aspartame can be quickly detected. This method does not provide relevant data on the thermal decomposition of sweeteners through derivative steps, and it also provides convenient accuracy from the large or small mass spectrometry fragments after the thermal decomposition of aspartame. By using this technology, the application can also be extended to other quantitative and synthetic sweeteners.
3. Liquid chromatography method
Efficient liquid chromatography has been applied in the field of food testing in China for a long time. And it has been well promoted, with the application characteristics of "three highs, one wide, and one fast". At present, liquid chromatography is a very important part of the distribution of preservatives and colorants in alcoholic foods. The liquid chromatography method is fast and simple in processing, and after configuring a secondary tube array detector, it can also detect various food additives at multiple wavelengths, thereby improving the efficiency of detection.
Experiments have shown that direct filtration, polyamide adsorption, and liquid-liquid distribution methods are used for the detection of wine samples. The final results showed that using direct filtration and liquid-liquid distribution to detect wine samples, the instrument baseline drift was relatively large and there were many impurities. However, using the polyamide adsorption method to obtain the final chromatogram, the baseline was relatively stable and the peak shape was also good, which was consistent with the detection results recommended by GB/T 5009.35 (Food Safety Testing Standards).
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