Determination of Fatty Acids in Sour Jujube by Gas Chromatography

Abstract: The water-soluble extract of jujube kernel is equivalent to 7.5g crude drug per ml. The stock solution is diluted into three concentrations of 1: 1, l: 0.5, 1: 0.25, pH = 9, and the dosage is 1.0ml per 20g.

Objective To determine the composition and content of fatty acids in jujube kernels. Methods Soxhlet extraction method was used to extract its fatty acids, followed by methylation, and separated and identified by gas chromatography-mass spectrometry. Results 17 kinds of fatty acids were isolated and identified from the jujube kernels, accounting for 95.33% of the total fatty acids, unsaturated fatty acids accounted for 80.20% of the total fatty acids, and saturated fatty acids accounted for 15.13% of the total fatty acids. Conclusion The main component of fatty acid in jujube kernel is unsaturated fatty acid.

The mature seeds of ZiziphusspinosaHu, a jujube plant from the family of Rhamnaceae. Sorbet jujube is also known as mountain jujube, acanthopsis jujube, thorn jujube and so on. Jujube is a deciduous shrub or small tree, which is mainly distributed in Liaoning, Hebei, Henan, Shaanxi and other provinces of China, and is also produced in Shandong, Shanxi, Inner Mongolia, Gansu, Anhui and other places [1]. Liaoning jujube resources are rich and widely distributed, especially jujube region in Liaoning is rich in jujube, with high quality and good output, but it has not yet been fully developed and utilized ("Liaoning Province Chinese Medicine Resources List" 1987). As a nourishing and tranquilizing medicine, Chinese medicine is often used to calm, calm and hypnotize. Sour jujube is sweet and smooth, with four classics: heart, spleen, liver and gall. It has the effects of nourishing the liver, calming the heart, calming, calming the nerves, condensing sweat and regenerating. Used for insomnia, convulsions, and cooling. Studies on the composition and content of fatty acids in jujube kernels are rare reports. In order to further study its application value, this article uses Soxhlet extraction method to extract fatty acids from jujube kernels in Chaoyang area, Liaoning Province. The measured yield is 34.6%, followed by methyl ester Chemical processing, using gas chromatography mass spectrometry computer combined technology to separate their chemical components, by searching the Nis98 spectral library, combined with standard mass spectrometry and related literature [2, 3], confirm its composition, and also use the peak area The monochemical method uses the G170LBA ChemStation data processing system to obtain the relative percentage of each fatty acid. This will provide a scientific basis for further development and utilization of jujube.

1 Instruments and materials

1.1 Instrument

HP6890GC / 5973MS type gas chromatography-mass spectrometry (GCMS) (Hewlett-Packard Company, USA); R2201 rotary evaporator (Shanghai Zhongke Machinery Research Institute).

1.2 Main reagents

Methanol, petroleum ether (60 ~ 90 â„ƒ), anhydrous methanol, anhydrous ether, sulfuric acid and sodium hydroxide are all analytically pure.

1.3 Sample processing of jujube kernels: Wash jujube seeds collected from Chaoyang, Liaoning in autumn 2003, dry naturally, remove the flesh and remove the cuticles, and get the jujube kernels to be crushed with a grinder and put them in a dry place for use .

2 methods

2.1 Extraction of jujube kernel fatty oil

Weigh 50.00g of crushed jujube kernels, put it in a filter paper cylinder, and then put it into a Soxhlet extractor, add 250ml of petroleum ether, reflux extraction for 8h to obtain a yellow transparent extract, and then use a rotary evaporator to remove the petroleum ether to obtain 17.3 g, yield 34.6%.

2.2 Methylation of fatty acids Take 0.5ml of jujube kernel fatty oil, add 2ml of n-hexane, and then add 1ml of NaOH methanol solution (0.5mol), put it on a water bath and reflux at 70 â„ƒ for 10min, take it out, cool and move it to the scale test tube, add water to 10ml , Shaking, ultrasonic extraction, centrifugation, and take the supernatant for GCMS analysis.

2.3 GC / MS analysis

2.3.1 Gas chromatography conditions Chromatographic column HP5 (30m Ã— 0.25mm Ã— 0.25Î¼m) elastic quartz capillary column. Heating program: Initial temperature 120 â„ƒ, 25 â„ƒ / min to 200 â„ƒ, 2.5 â„ƒ / min to 230 â„ƒ, and finally 10 â„ƒ / min to 270 â„ƒ. Vaporization temperature 290 â„ƒ; sample injection volume 0.2Î¼l; carrier gas (He) flow rate 1ml / min; split ratio: 50: 1; solvent delay 3min.

2.3.2 Mass spectrometry conditions

Electron bombardment (EI) ion source; ion source temperature 230 â„ƒ; quadrupole temperature 150 â„ƒ; multiplier voltage 1345V; electron energy 70eV; emission current 34.6Î¼A; interface temperature 230 â„ƒ; mass scanning range m / z20 ï½ž 500.

3 results

According to the results of the experiment carried out according to the experimental steps, the total ion current diagram of the fatty acid methyl ester of jujube seed was given by ChemStation, as shown in Figure 1:

Through the G170LBA ChemStation data processing system, the quantitative analysis was carried out according to the area normalization method. The fatty acids in the jujube kernels and the relative percentages of the obtained fatty acids in their oils are listed in Table 1. Table 1 Identification results of chemical constituents in Sour jujube kernels (omitted) From Table 1, it can be seen that 17 kinds of fatty acids have been identified in Sour jujube kernels, accounting for 95.33% of the total fatty acids. Mainly contains 11 kinds of saturated fatty acids accounted for 15.13% of total fatty acids; 6 kinds of unsaturated fatty acids accounted for 80.20% of total fatty acids, of which octadecanoic acid accounted for 39.26% of total fatty acids, 9,12 octadecadiene Acid accounts for 29.62% of the total fatty acids, and linoleic acid accounts for 9.32% of the total fatty acids. From the above experimental results, it can be seen that the main chemical component of sauerkraut kernels is unsaturated fatty acids accounting for 80.20%. Studies have shown that such unsaturated fatty acids are fatty acids that cannot be synthesized in the human body and are essential. They can relieve excess cholesterol in the blood and enhance cell membrane permeability , Prevent functions such as myocardial tissue and arteriosclerosis. The body's intake of unsaturated fatty acids can also directly affect the synthesis of prostaglandins, which has many effects on the body.

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