Chromatography - Gel permeation
Waters (1515), Agilent Technologies (1260Infinity)
Gel permeation chromatography is a type of liquid chromatography. The principle is that a polymer solution is passed through a column filled with gel, and the column is separated according to molecular size. The column is a glass column or a metal column, filled with a spherical gel with a high degree of cross-linking. The spherical gel itself has many holes with different sizes according to a certain distribution.
According to the different strokes of the molecules, the high polymer can be mixed together. The material molecules are separated step by step, the first is the separation of large molecules, and the smaller polymer molecules are separated by the solvent molecules and then separated, and then the concentration and molecular weight of the solute in each stage are detected by a certain method.
Gel chromatography (GPC) can measure the average molecular weight, molecular weight distribution, molecular weight distribution width of high molecular polymers (including olefin polymers), oligomers, sugars, proteins, etc., and analyze homopolymers and impurities in copolymers .
THF and chloroform phases require molecular weights of 5 to 1.5 million, DMF mobile phases require molecular weights greater than 20 to 1.5 million, and absolute molecular weight tests require molecular weights greater than 3,000. (The number average molecular weight is less than 500 is not accurate, and there will be errors in data processing) Absolute molecular weight currently only supports tetrahydrofuran and chloroform phases
Requirement on Sample
- The sample must be fully soluble in the selected mobile phase;
- The solid sample volume requirement is at least 10mg; please try to dissolve the sample in advance, the concentration range: 2-3mg/mL
- The amount of liquid sample is not less than 2mL, the concentration is preferably greater than 5mg/mL, please inform the specific concentration.
The sample can be partially dissolved. Can the supernatant be taken for testing?
- No, because if the solubility is not good, the molecular weight of the insoluble components cannot be tested, and if the solubility of the sample is poor, the sample may precipitate on the chromatographic column and destroy the column.