How To Choose The Solvent Filtration Membrane In Liquid Chromatography
The liquid chromatography is a kind of high-precision, high-sensitivity qualitative and quantitative analysis instrument. Due to the quite precise components of LC and high accuracy and sensitivity of detection, the purity requirements of the sample and mobile phase are also quite high in the process of detecting samples.
Three types of filtration membrane in LC
Before the LC detection, the mobile phase must be filtered to remove impurities after the mobile phase is selected. The solvent filter is mainly used and equipped vacuum pump to speed up the filtration rate. Among them, the filter membrane plays a key role. Depending on the mobile phase solution, the type of membrane used in the solvent filter varies. The filter membrane is mainly divided into two types: water-based and organic-type membranes. The pore size of these two types of filter membranes is very small and the filtering effect is good.
Water-based membranes are suitable for water-based solutions, are not resistant to organic solvents, have high chemical and thermal stability, fast flow rates, strong resistance to acids and alkalis, high mechanical strength, and low protein adsorption.
Organic membranes are hydrophobic membranes, suitable for organic solvents and air filtration, which is acid and alkali resistant, antioxidant, with high-temperature resistance, good strength, and stable chemical properties. It is not only suitable for aqueous solutions containing acid and alkali, but also for organic solvents such as alcohols, hydrocarbons, lipids, phenols, ketones, and other organic solvents.
In addition, there is a filter membrane made of aliphatic nylon, which has good hydrophilicity and resistance to appropriate concentrations of acids and bases. It is not only suitable for aqueous solutions containing acid and alkali, but also for organic solvents, such as alcohols and hydrocarbons. , Ethers, Esters, ketones, benzene and benzene homologs, dimethylformamide, dimethylsulfoxide, etc., which is one of the most widely used microporous filter membranes.
After a period of use, the filter membrane will be polluted or blocked to reduce the water permeability and slow down the filtration speed. Therefore, it is necessary to clean the filter membrane in time to extend the life of the membrane and restore separation performance such as the water flux of the membrane. When the permeate or effluent quality of the membrane is significantly reduced or the pressure difference between the inlet and outlet of the membrane device exceeds 0. 05 MPa, the membrane must be cleaned.
The filter membrane cleaning method can be selected from water washing, air-water mixed washing, counter-current washing, hot water washing, etc. When the pollutants cannot be washed with water, an appropriate cleaning agent can be selected for removal. The selection of cleaning agents must be good for the pollutants. The ability to dissolve and decompose without contaminating and damaging the membrane surface. In specific operations, the cleaning method should be selected according to the configuration of the module, the material of the membrane, the type of the pollutant and the degree of pollution.
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