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산업 정보Determination of γ-linolenic acid and di-high γ-linolenic acid

Determination of γ-linolenic acid and di-high γ-linolenic acid

2019-09-19

Abstract: A gas chromatography area normalization method for the determination of γ-linolenic acid and di-high γ-linolenic acid was established. Γ-linolenic acid and di-high γ-linolenic acid are completely consistent in sample processing and chromatographic conditions, only the peak time is different. The precision, reproducibility, recovery experiments, γ-linolenic acid RSD are respectively For 1.51, 1, 89%, and 0.98%, the two high gamma-linolenic RSDs were 1.45, 1.15%, and 0.81, respectively. Correlation analysis r values reached extremely significant levels. The area normalization method for the determination of γ-linolenic acid and di-high γ-linolenic acid can achieve the purpose of simplicity, accuracy, rapidity and small error.
Key words: γ-linolenic acid; di-high γ-linolenic acid; gas chromatography CLC number: O 657.71 Document code: A Article ID: 1672—5425(2005)011005O—O3
Synthetic prostaglandin E (Prostaglamdi E) is a precursor of linolenic acid isolated from evening primrose oil [1]. Γ-linolenic acid is synthesized by a reduction reaction, a sulfonation reaction, a carbonation reaction, a hydrolysis reaction, and the like, and then biosynthesized prostaglandin E.
High-purity γ-linolenic acid can synthesize di-high γ-linolenic acid, so it is necessary to establish a rapid and simple method for the determination of γ-linolenic acid and di-high γ-linolenic acid to ensure quality control. At present, the domestic determination of γ-linolenic acid is mostly by gas chromatography external standard or internal standard method [2]. For the detection of di-high γ-linolenic acid, infrared spectroscopy has been reported [1]. The author established the experiment by gas chromatography. The area normalization method is used to calculate γ-linolenic acid and di-high γ-linolenic acid.
l experiment
1.1 Instruments and reagents: Nanjing Kejie Analytical Instrument Co., Ltd. GC5890 gas chromatograph (capillary injection system, FID) water bath; γ-linolenic acid standard, two high γ-linolenic acid standard, two high γ- Linolenic acid samples (self-synthesis), γ-linolenic acid samples (enriched from evening primrose oil), K0H, FB3-ether, petroleum ether, methanol, all of which were of analytical grade.
1.2 Methods
1.2.1 Chromatographic conditions: column: capillary column (30m × 0.25mm), temperature: 230 ° C in the oven, 250 ° C inlet, detector 280 ° C; pressure: N2 0.5MPa, H2 35ml / min, Air400 Ml/min
1.2.2 Treatment of samples and standards: Take 4 drops of sample or standard in a 10 mL stoppered test tube, add 2 mL of 0.5 mol/L K0H methanol solution, saponify for 20 min in a 63 °C water bath, and add 0.2 mL of BF3-ether solution, methyl esterification in a water bath at 63 ° C for 5 min, cooled in cold water, added with 2 mL of petroleum ether, shaken, and pipet the upper layer of 2 L, calculated according to the area normalization method.
2 Results and discussion
2.1 Correlation between the content and content of γ-linolenic acid peaks in different batches of γ-linolenic acid, di-high γ-linolenic acid and evening primrose oil
2.1.1 Correlation between the area and content of γ-linolenic acid peaks in different batches of evening primrose oil γ-linolenic acid and three-package γ-linseed in different batches of evening primrose oil The correlation between peak area and content (%) of acid reached a very significant level (r=0.992). The calculation of γ-linolenic acid content by area normalization method was simple, rapid and error-free because of the chromatogram. Under the conditions, the five fatty acids in the evening primrose oil can be completely separated. When the purity of evening primrose oil γ-linolenic acid is more than 90, it is mainly γ-linoleic acid and γ-linolenic acid (see Figure lb). The correlation between peak area and content (%) of γ-linolenic acid after enrichment in different batches also reached a very significant level (r=0.9997).
2.1.2 Correlation analysis of peak area and content of two high-yield γ-linolenic acid in different batches When the content of the second high γ-linolenic acid was normalized by area, the correlation between peak area and content reached a very significant level. (r=O.9842), since the synthesis of dihomo-gamma-linolenic acid is from the high-purity γ-linolenic acid, there are only two peaks, but the peak time is delayed (see Figure 1c). ).
2.2 Investigation of linear relationship: accurately weigh 20 mg of γ-linolenic acid or di-high γ-linolenic acid standard in a 1O mL volumetric flask, and treat it according to the method of 1.2.2, and accurately absorb 2 mL of petroleum ether. The extracted supernatants were subjected to chromatography analysis of 1.0 L, 1.5 L, 2.0 L, 2.5 L, and 3.0 L according to the chromatographic conditions of 1-2.1. The results are shown in Table 3.
Table 3 shows that the peak area integral scores and contents of γ-linolenic acid and di-high γ-linolenic acid are extremely significant in the range of 10 to 30 g, and the r values are 0.995 and 0.9997, respectively.
2.3 Precision and reproducibility investigation: precision inspection; precision extraction of standard solution (10μg / mL) 1μL into the gas chromatograph for 5 consecutive 5, record the peak area integral value.
Reproducibility study: Take 1 μL of the self-made sample, repeat 5 times of sampling, and record the peak area integral value. The precision RSD of γ-linolenic acid and di-high γ-linolenic acid was 1.51 and 1.45%, respectively, and the reproducible RSD was 1.89 and 1.15, respectively.
2.4 Determination of recovery rate: accurately weigh the appropriate amount of sample, accurately add a certain amount of standard, according to the sample processing operation, injection 2 μL, according to the relationship between the peak area and content obtained by the correlation into the content. The results are shown in Table 4.
The results in Table 4 show that the average recoveries of γ-linolenic acid and di-high γ-linolenic acid are 98.92 and 99.44, respectively, and the RSD is 0.98 and 0.81, respectively, indicating that the sample treatment is reliable.
3 Conclusion
(1) Correlation analysis of peak area and content of γ-linolenic acid in different batches of evening primrose oil can be seen as correlation coefficient r=O. 992, reached a very significant level, combined with the map, the fatty esters of evening primrose oil are mainly stearic acid, palmitic acid, oleic acid, linoleic acid and a γ-linolenic acid five kinds of fatty acids, under the chromatographic conditions, The separation of these five fatty acids is good, so the area normalization method can be used to calculate the content. After enrichment, the correlation between the area and content of γ-linolenic acid peak with purity above 90 is known, r=0.9997, which also reached a very significant level. After enrichment, only linoleic acid and γ-flax remained. Two components of acid.
(2) Correlation analysis of the peak area and content of different batches of di-high γ-linolenic acid reached a very significant level, and the area normalization method can also be used to calculate the content under the chromatographic conditions, but The difference between γ-linolenic acid and di-high γ-linolenic acid is only inconsistent in peak time.