Separation And Purification Of α-Linolenic Acid In Mixed Fatty Acid From Silkworm

Alpha-linolenic acid(ALA)has physiological activities.In this work,the mixed fatty acid was prepared from silkworm,then the separation and purification ofα-linolenic acid, and its analysis conditions by gas chromatography(GC)and high performance liquid chromatography(HPLC)was studied.Futher,the complexing extraction of methylα-linolenate with silver nitrate and the separation via adsorption on D72 resin loaded with Ag⁺ ion were researched.All these were helpful for the production ofα-linolenic acid.The results are as follows:1.Analysisingα-linolenic acid by GC,the oil consisted mainly of palmitic acid 18.97%, stearic acid 5.48%,oleic acid 37.15%,linoleic acid 5.15%,α-linolenic acid 32.33%by area normalization method.Analysisingα-linolenic acid by derivative HPLC withα-bromoacetophenone,the mixed fatty acids got baseline separation on the HC-C8 column when using acetonitrile:water=90:10 as mobile phase.The result showed that the content ofα-linolenic acid was 34.03%in mixed fatty acids.2.Extraction yield and purity of ALA-Me as index,the complexing extraction conditions of ALA-Me with silver nitrate was discussed according to single-factor test. Experiment results showed the optimized complexing extraction conditions were as follows: ALA-Me in petroleum was extracted with 2mol·L^-1silver nitrate in 40%methanol-water solution at 0℃for 2 hours,then the extractant was re-generated with petroleum ether at 50℃for 30min.The purity of obtainedα-linolenic acid methyl ester and its yield were 97.9%, 44.3%respectively.3.Isolation of ALA-Me by adsorption on D72-Ag⁺ resin,the concertration of silver ion in pre-treatment and solvent have great effects on adsorption,the optimized conditons were C_AgNO3=1mol·L^-1and using 95%ethanol solution as solvent.Futhermore,the concentration of ALA-Me,flow rate,temperature affected of breakthrough curves and elution reagent affected of elution curves were studied.The results showed that by using a fixed bed packed with D72-Ag⁺ resin,the content of ALA-Me in the mixed fatty acid methyl esters from silkworm was raised from 35.1%to 92.0%with a recovery of 83.71%,ALA-Me was enriched effectively.