Separation of high‐purity eicosapentaenoic acid and docosahexaenoic acid from fish oil by pH‐zone‐refining countercurrent chromatography

Self Cite

Tocopherol homologues are important fat‐soluble bioactive compounds with high nutritional value. However, it is of great challenge to separate these homologues because of their high structural similarities. In this work, ionic‐liquid‐based countercurrent chromatography was used for the separation and purification of tocopherol homologues. Conventional countercurrent chromatography and ionic‐liquid‐based countercurrent chromatography solvent systems were evaluated in respect of partition coefficient, separation factor, and stationary phase retention factor to separate these targets. Kind of ionic liquids, amount of ionic liquid, and sample amount were systematically optimized. A novel countercurrent chromatography non‐aqueous biphasic system composed of n‐hexane‐methanol‐1‐butyl‐3‐methylimidazolium chloride was established. The baseline separation of tocopherol mixtures was obtained in one cycle process. The ionic liquid played a key role in the countercurrent chromatography separation, which resulted in difference of partition behavior of individual tocopherol in the whole system through different hydrogen‐bonding affinity. Finally, n‐hexane‐methanol‐1‐butyl‐3‐methylimidazolium chloride (5:5:3, v/v) water‐free biphasic system was successfully applied to separate tocopherol homologues from vegetable oil that was not achieved beforehand. This method can be widely employed to separate many similar molecules such as tocotrienols, tocomonoenols, and marine‐derived tocopherol in food samples.

Section: Effect Of Ionic Liquid Anionmentioning

confidence: 99%

Efficient separation of tocopherol homologues in vegetable oil by ionic‐liquid‐based countercurrent chromatography using a non‐aqueous biphasic system

Fan

Cao

2019

Self Cite

“…As for efficient separation of alkaloids and organic acids, pH-zone-refining counter-current chromatography (PZR-CCC) would be a unique choice [17][18][19][20][21]. PZRCCC is a kind of liquid-liquid partition chromatography based on that acid or basic targets could be trapped by the trailing border to form pH zones containing pure targets and it produces a succession of concentrated rectangular target peaks eluted according to their pK a values and hydrophobicity, while charged impurities are concentrated at the peak boundaries [22,23].…”

Section: Introductionmentioning

confidence: 99%

An efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment, separation, and purification of alkaloids and organic Acids from natural products

et al. 2020

This study presents an efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment, separation, and purification of alkaloids and organic acids from natural products. First, an acid or base modified two‐phase solvent system with maximum or minimum partition coefficient was developed for the liquid‐liquid extraction of the crude extract. As a result, alkaloids or organic acids could be selectively enriched in the upper or lower phase. Then pH‐zone‐refining counter‐current chromatography was employed to separate and purify the selectively enriched alkaloids or organic acids efficiently. The selective enrichment and separation of five bufadienolide from toad venom of Bufo marinus was used as an example to show the advantage of this strategy. As a result, 759 mg of selectively enriched bufadienolide was obtained from 2 g of crude extract and the total content of five targets was increased from 14.64 to 83%. A total of 31 mg of marinobufagin‐3‐adipoyl‐l‐arginine, 42 mg of telocinobufagin‐3‐pimeloyl‐l‐arginine, 51 mg of telocinobufagin‐3‐suberoyl‐l‐arginine, 132 mg of marinobufagin‐3‐suberoyl‐l‐arginine, and 57 mg of bufalin‐3‐suberoyl‐l‐arginine were all simultaneously separated from 500 mg of selectively enriched sample, with the purity of 92.4, 97.5, 90.3, 92.1, and 92.8%, respectively.

“…The two acids could not be completely separated in the pH‐zone‐refining mode after optimization of separation conditions, including selection of the biphasic solvent system, type and concentration of retainer and eluent, and elution modes used. In pH‐zone‐refining countercurrent chromatography, the acid dissociation constant (p K a ) value and hydrophobicity are two important factors for successful separation [27]. The occurrence of a zone of overlap in pH‐zone‐refining countercurrent chromatography is generally caused by one of the following three issues: sample overloading, components having similar p K a values and hydrophobicity (an apparent factor), or the p K a values and hydrophobicity of the two solutes acting in opposite ways (a covert factor) [28].…”

Section: Introductionmentioning

confidence: 99%

Retention mechanism of pH‐peak‐focusing in countercurrent chromatographic separation of baicalin and wogonoside from Scutellaria baicalensis Georgi

Wang

Zuo

Wang

et al. 2020

An efficient and target-oriented pH-peak-focusing countercurrent chromatographic method was established for large-scale separation of baicalin and wogonoside from the crude exact of traditional Chinese medicinal herb Scutellaria baicalensis Georgi. An optimized two-phase solvent system composed of n-butanol-ethyl acetate-methanol-water (1:4:0.5:5, v/v) was selected. Trifluoroacetic acid (10 mmol/L) was added to the upper organic phase, used as the stationary phase. One liter of the aqueous lower phase was used as the mobile phase for 0-350 min, and then 10 mmol/L ammonia was added to remaining 1 L of the aqueous lower phase and used as the mobile phase for 350-600 min. In total, 493.2 mg of baicalin with 98.6% purity and 88.6 mg of wogonoside with 98.9% purity were obtained from 1.0 g of crude exact of S. baicalensis by countercurrent chromatography in a single run. The acid dissociation constant (pKa) and oil-water partition coefficient values of two components were measured to better understand the mechanism of separation. Results showed that pH-peakfocusing countercurrent chromatography with a polar solvent system added with trifluoroacetic acid could be an efficient method for large-scale isolation of organic acids, which are difficult to separate with conventional countercurrent chromatography due to their poor solubility in non-polar solvents.