Quantitative analysis of monoglyceride by the hott

2022-09-19
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Quantitative analysis of monoglyceride by high performance gel chromatography is a widely used food emulsifier, which has a good application prospect in food additives. The emulsifying capacity of diglyceride in crude monoglyceride products is only 1% of monoglyceride, so the quality of monoglyceride products depends on the content of monoglyceride. But so far, no accurate, rapid and effective method has been reported for the quantitative analysis of monoglyceride in China. The traditional method is to use chemical analysis, through oxidation α The ortho hydroxyl of monoglyceride is used to calculate the content of monoglyceride. This method is applicable to β Monoglyceride is powerless, and β Monoglyceride is inevitable in the synthesis of monoglyceride. Therefore, using chemical methods to determine the content of monoglyceride is not only complicated, reagent consumption is large, but also the deviation is large. It is necessary to find a more effective analysis method to adapt to the production and development of monoglyceride. In view of the fact that crude monoglyceride products generally contain glycerol, monoglyceride, diglyceride and triglyceride, and the difference between their molecular weights is relatively large, and gel chromatography can be used to separate substances with different molecular weights, this paper adopts this method to realize the quantitative analysis of monoglyceride

I Instruments and drugs

waters 150C liquid chromatograph

water 740 data processor

tetrahydrofuran: C.P. or A.R., dry with sodium and distill for standby

chloroform: A.R. Guangzhou solvent factory product

acetone: A.R. Guangzhou solvent factory product

crude monoglyceride: more than 90%, imported from Denmark

silica gel: 60 ~ 200 mesh for chromatography, made in Shanghai

silicone sheet: self made

II. Preparation of monoglyceride standard samples

quantitative analysis should be carried out to analyze the largest number of graphene patents applied by China. First, there must be a standard sample. There is no standard sample of monoglyceride sold at home or even abroad. The highest content sample we can get is imported from Denmark, and its content is only 90%. Through exploration, we use silica gel column chromatography to refine high-purity monoglyceride from crude monoglyceride

1. Selection of thin plate conditions

before column chromatography, use thin plate chromatography meter to select the solvent system of column chromatography. Through experiments, the solvent system composed of 95% volume chloroform and 5% volume acetone can separate monoglyceride, diglyceride and triglyceride on silica gel thin plate

2. Column chromatography separation and collection of monoglyceride

take the heat dissolving system determined above as eluent, weigh 100g of silica gel, and fill it with wet method in a glass chromatography column with a diameter of 2.2 cm to obtain a uniform silica gel column. Add 3 grams of monoglyceride dissolved with detergent at the upper end of the column (add it evenly with a long burette), and the flow rate is controlled at about three drops per second. Use a 5O ml small conical flask to collect the washing out liquid, change a small conical flask for every 25 ml collected, and continuously collect about 500 ml. then, check the thin-layer plate one by one to determine which small conical flasks contain only monoglyceride. During the experiment, we found that under such a solvent system, the solubility of monoglyceride changes greatly with temperature, which puts forward conditions for us to enter the crystallization of the sample. In order to obtain high purity monoglyceride, we recrystallized the monoglyceride obtained by column chromatography. Chromatogram comparison before and after purification

we have carried out necessary instrumental analysis (infrared spectrum, nuclear magnetic resonance, elemental analysis) on the purified sample, and the results show that the sample is very pure and can be used as a standard sample

III. chromatographic analysis of monoglyceride

after a series of exploratory tests, the monoglyceride mixture can be well separated by using the following experimental conditions: chromatographic column u-styragel 100a.u-styragel 1000A in series

temperature: room temperature

flow rate: l ml/min

solvent: tetrahydrofuran

detector: ri (differential)

quantitative method: external standard method

use the above conditions, We quantify a series of monoglyceride samples with different contents

IV. results and discussion

the content of a series of monoglyceride samples was measured by GPC method, and compared with the results of chemical analysis method

it can be seen that the content of monoglyceride measured by gel chromatography is higher than that measured by chemical method. The main reason is that chemical method can not be measured β Due to monoglyceride, the result is low. From the chromatogram, we can see that if necessary, changing the experimental conditions, it is possible to further separate triglyceride and diglyceride to realize the quantification of diglyceride and triglyceride. Based on the above work, the following conclusions are drawn:

1. High purity monoglyceride can be separated from crude glyceride by silica gel chromatography column. From the chromatography, it can be seen that the obtained monoglyceride has no heteropeak, and the peak shape is symmetrical. After necessary instrument analysis, it shows that its purity is reliable, but colleagues and customers also bring the product samples to be tested in their factory as the standard sample

2. The quantitative analysis of monoglyceride by gel chromatography is simple, rapid, sensitive and reproducible. Under the experimental conditions, the separation effect of monoglyceride and other components in the mixture is ideal. The experimental machine can be used for quantitative analysis of monoglyceride, and it should have automatic alarm and shutdown devices

references

[1]kanfman H.P., grease, soap, paint 73, 381971

[2]berner G.J., chromatographic analysis 643881972

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