Selection of Liquid Phase Pretreatment Syringe Filter
A. The choice of filter:
When purchasing a filter, first consider the chemical compatibility, that is, whether the filter is resistant to acids, alkalis, organic solvents, etc.
1. The pore size of the filter:
Aperture 0.45μm filter: It is often used for the filtration of conventional sample mobile phases to meet general chromatographic requirements. Such as: chromatography system for 3μm or larger particle size fillers.
A 0.22 μm pore size filter: removes the requirements of very fine particles in the sample and mobile phase. Such as: chromatography system for <3μm packing.
Aperture 1-5μm filter: It is often used for turbid solution which is difficult to handle. It can be pre-filtered with 1-5μm filter and then filtered with corresponding filter.
2. Characteristics of the filtered sample:
A: Hydrophilic sample: It is suitable to use a hydrophilic membrane, which is suitable for filtering water as a matrix solution. Such as: tap water, surface water, available filter membranes: water film (mixed cellulose ester), nylon film (polyamide).
B: A sample of an organic or inorganic compound (alcohol, ester, oil) is a nylon film (polyamide).
C: Protein solution sample: a membrane suitable for low protein adsorption. That is PVDF film.
D: A strong acid and alkali sample is suitable for hydrophobic PTFE (polytetrafluoroethylene film).
2. Syringe Filter selection:
Enclosure: High-pressure polypropylene (PP) is resistant to high temperatures, does not leak, does not need to change membranes and cleaning, and eliminates the cumbersome and time-consuming preparations. It is a small sample of HPLC and GC.
Filter size selection: commonly used Φ13mm, Φ25mm two, that is, the sample volume 2-10ml select Φ13mm, the sample amount 10-100ml select Φ25mm.
Characteristics and applications of several commonly used filters:
1. aqueous membrane (mixed cellulose ester CA)
Characteristics: uniform pore size, high porosity, no media shedding, thin texture, low resistance, fast filtration rate, low cost, but not resistant to organic solutions and strong acids and alkalis. Application: drinking water, surface water, well water, etc., sterilization filtration, analysis of particulate and oil insoluble in solution, determination of water pollution index, filtration of particles and bacteria such as gas, oil, beverage, wine. For sample pretreatment filtration, Zui is one of the widely used filters.
2. Nylon membrane (polyamide NYLON)
Features: good temperature resistance, can withstand 121 °C, saturated steam autoclave for 30 minutes, maximum working temperature 60 °C, good chemical stability, can withstand dilute acid and alkali and other organic and inorganic compounds, solvents. Application: Suitable for filtration of electronic, microelectronics, semiconductor industry water filtration, tissue culture media, liquid medicine, beverages, high purity chemicals, water and organic solution mobile phase.
3.PVDF membrane (polyvinylidene fluoride)
Characteristics: The film has high mechanical strength, good tensile strength, good heat resistance and chemical stability, low protein adsorption and strong hydrophobicity. Applications: Gas and steam filtration, high temperature liquid filtration, tissue culture media, additives and other sterilization filtration, solvent and chemical raw materials purification and filtration.
Features: Wide range of chemical compatibility, good temperature resistance, strong acid and alkali, chemically corrosive solvents and oxidants. Applications: Chemical, pharmaceutical, environmental, electronics, food, energy and other fields can filter almost all organic solutions.