The Study On Purification Of Natural Tocopherols By Column Chromatography

Tocopherol is a fat-soluble vitamin.It is widely used in medicine,health care products,foodstuffs,cosmetics and feed industries owing to its excellent pharmacological effects, nutritional value and antioxidant role. At present,high purity tocopherol (content above 90%) domestic and international market demand supply,therefore,Study of high purity tocopherol efficient purification method is not only good value for research,but also has broad application prospects. In this paper,the purification of tocopherols and conditions is studed by column chromatography method,adsorption resin as fillera,tocopherol concentrates(content of approximately 50%)as raw material. The results are as follows:1.The HPLC methods is established in the purification process as a means of quantitative measurement of target products.The chromatographic conditions were as follows:V (methanol) : V (water) =98:2 as the mobile phase,C18 column as the stationary phase.sample volume:20μL,the detection wavelength :292nm,Velocity : 1mL/min,Column temperature : 35℃. 2. Experimental adsorption resin The adsorption capacity of tocopherols in different resins has been determined by static method. The results showed that the static adsorption capacity to tocopherol/g dried resin on ND-Ⅰresin are 449.17mg ( 30℃) and 359.34 mg (35℃),and which on ND-Ⅱresin are 263.30mg(30℃) and 191.55mg(35℃)respectively. Therefore,it's clear that ND-Ⅰresin is superior to ND-Ⅱresin. The curve of isothermal absorbtion showed that the adsorption is single molecular adsorption,and the absorbtion process can be followed by Langmuir equation. The absorbtion equation is q = 94.07c / (1+0.1988c) at 30℃,the ammount of saturated adsorption to tocopherol/g dried resin is 458.53 mg;The adsorption equation is q =144.85c / (1+0.3934c) at 35℃,the amount of saturated adsorption to tocopherol/g dried resin is 371.36 mg. The results showed that no matter what kind of resin used, the adsorption capacity has decreased with increasing temperature. So the lower temperature used is better for adsorption,but theprecipitation in the tocopherol solution will be occured when the temperature is less than 30℃. Therefore,the static adsorption can be carried out at tempearture 30℃.The adsorption curves and desorption curves of tocopherols on adsorption resins were determined with the adsorption column of inner diameter 20 mm and resin packing height 224 mm. From the absorption curves,the tocopherol begin to penetrate the ND-Ⅰresin when1.5BV used,and the adsorption of tocopherol can be reached to saturation when 3.5BV used. In the other hand,the tocopherol begins to penetrate the ND-Ⅱresin when 0.2BV used. From the desorption curves,the peak of tocopherol in ND-Ⅰresin is the highest when 1.6BV used,and the peak trail is not serious. However, the peak of tocopherol in ND- II resin is the highest when 2.4BV used,and the peak trail is serious. From the experimental results of the static adsorption and dynamic adsorption,ND-Ⅰresin is selected to use for purifing tocopherol.3. The purifing copherols technologyThe purification of tocopherols was studied by column chromatography with ND-Ⅰresin as adsorbents,and the effects of column temperature,velocity,tocopherol concentrations,desorption agent and its concentration on the purification were also investigated. Through adsorption and desorption experiments,the best experimental conditions are obtained as follows:temperature is 30℃,flow rate of adsorption is 2.5mL/min and desorption velocity is 2.0mL/min,The tocopherol concentration (c0) is 10.80g/100mL,5% acetic acid-ethanol solution as desorption agent. Tocopherol content can be purified to more than 90%. The resin Life inspection indicated that the resin can be reused after treatment. It could be found that the regenerated resin can be used five times,both of tocopherol content and yield can reach above 90%.Under the conditions of best optimum experiment,the purification of the actual tocopherol sample was studied by column chromatography. Three examples have showed that the ND-Ⅰresin handling capacity is 90mg tocopherol /milliliter,the content of tocopherol products is about 95%,the total recovery rate of tocopherol can be above 90%.