Chromatography

Firstly, let us learn something about the adsorption mechanism of reversed-phase extraction and normal phase extraction. Reversed-phase extraction separation mainly uses the non-polar force between C-H bonds on SPE functional groups and C-H bonds of target compounds. In general, non-polar reversed-phase SPE columns are more suitable for extraction and separation of non-polar target compounds or target compounds with moderate polarity from polar matrices. Target compounds adsorbed on nonpolar SPE columns by nonpolar forces can be eluted with nonpolar solvents, such as chloroform, cyclohexane, and ethyl acetate. The target compound can be eluted from the SPE column successfully as long as the solvent elution strength is sufficient to destroy the van der Waals force between the target compound and the non-polar functional group of the adsorbent. Even methanol with strong polarity has sufficient nonpolar force to elute many compounds. Sometimes single solvent fails to elute a hydrophobic t

Extract vitamin K1 from low fat plant samples such as fruits and vegetables with isopropanol and n-hexane. Purify Vitamin K1 by prep column and remove chlorophyll and other interfering substances, then separate vitamin K1 from other impurities with C18 LC column After zinc being reduced, detect with fluorescence detector and quantify with external standard method. (Spinach and apples are selected in this experiment) Reference standard: GB 5009.158-2016 National Food Safety Standard-Determination of Vitamin K1 in Food SPE column: Welchrom® Vitamin K1 Specification: 2g/6mL Activation: 5mL n-hexane, discard Sample loading: after injecting all the purified liquid, discard Rinsing: rinse with 5mL n-hexane and discard. Elution: elute with 15mL mixture of n-hexane and ethyl acetate, collect it in a 50mL centrifuge tube and drain. Blow with nitrogen to near-dry, add it to 5mL with methanol, then filter through 0.22 µm membrane for detection of HPLC. Column: Ultisil® XB-C18 4.6×250mm, 5 µm; Ult

Vaccines, as a hot word in 2020, will be frequently referred for a long time in the future. Vaccination is the most economical and effective public health intervention for the prevention and control of infectious diseases. It is also an effective means for families to reduce the incidence of diseases among members and the cost of medical treatment. Production time of vaccines vary and it may take 22 months to produce a single batch for some vaccines. The development of a vaccine is a long and complex process with high cost. In order to ensure the safety and effectiveness of the vaccine and reduce the side effects of the vaccine and immune interference of impurities, it is necessary to effectively separate and purify the vaccine, to remove other impurities in the cell culture medium, and to improve the content and purity of the effective components of the vaccine. This passage briefly introduces the current methods of vaccine separation and purification, as well as the application, deve

In liquid chromatography, for samples with complex components, it is often difficult to use a single chromatographic system to achieve ideal separation effect. Either the separation time is too long, or the separation degree is too poor.  In this case, gradient elution can shorten the analysis time and improve the separation effect. Let's see an example of gradient optimization and experience how it influences the separation effect. Precautions of establishing gradient method: 1. Try to develop methods on instruments that can test the project for a long time. 2. It is necessary to understand the property of the system so as to avoid problems that it cannot be reproduced after changing the instrument system. 3. Two basic facts of the system should be known: gradient lag volume and proportional accuracy.  These two data can be obtained in the same experiment: refer to the Experiment of Gradient Error in JJG 705 2014 Liquid Chromatograph Verification Regulation: add an ultraviolet det