With low cost, small size, large filtering area, fast filtering speed, low blocking rate, acid and alkali corrosion resistance, long service life, the syringe filter is widely used in the laboratory, without time-consuming and effort-consuming preparations. We also need to know the factors affecting the filtering effect. HAWACH has summarized five factors for your reference and is welcome to contact HAWACH team for more details.1. Particle type
The particle type is closely related to the filtering effect. The particles are divided into two types: deformable particles and non-deformable particles. For the deformable particles, such as the gel filtration, it will cause filter meshes block. The non-deformable particles, it will form a cake-like object on the filter membrane.2. Actual operating conditions
The filtration is also affected by actual operating conditions, such as particle flow rate and filtration pressure. Generally, the lower the flow rate, the better the retention effect. The practice has proved that the structure movement of the membrane is unfavorable to filtration. During the filtration process, the particles and fibers will precipitate from the deep filter, when the membrane structure changes and it will affect the filtration effect. However, the velocity/pressure difference only has an important effect on adsorption retention and has a relatively small effect on size exclusion.3. Filtration membrane
Different filtration membranes have different pore sizes and structures. For the pre-filtration membrane’s rated pore size, there is no unified national standard. It varies for different manufacturers, as they have their own methods. The public pore size of sterilization filtration is defined by laws and regulations, and all businesses implement the same standard, so it is relatively simple to select and replace.4. Fluid characteristics
For example, the mixing/contact time of the fluid and the membrane also has a greater impact on the filtering effect. The mixing/contact time is in direct proportion to the filtering effect. For the viscosity and chemical/ionic composition of the fluid, the greater the viscosity of the fluid, the slower the flow rate under the same pressure conditions. There will be more contact between the fluid and the membrane, and the filtration effect will be better. In addition, it should be noted that the characteristics of the fluid only affect the adsorption and retention effect of the membrane on the fluid, and do not affect the elimination of particle size.5. Filter materials
The filter material is divided into hydrophilic (water can be wetted) and hydrophobic (water can not be wetted), based on the relationship with water. Hydrophilic syringe filters are mainly used in water or water/organic solution mixing filtration and sterilization filtration, such as cellulose materials (regenerated cellulose, mixed cellulose ester), PVPP polycarbonate, PVDF modified polyvinylidene fluoride Ethylene; Hydrophobic filters are used in filtration of solvents, acids, alkalis and chemicals, tank/equipment respirators, process gas, fermentation intake/exhaust filtration, such as PTFE, Polytetrafluoroethylene, PVDF polyvinylidene fluoride, polypropylene, polysulfone, polycarbonate, etc.
Here are some frequnely used filter membranes in the syringe filter.1) Nylon membrane (Nylon)
Features: the membrane of Nylon syringe filter have good temperature resistance, can withstand 121 saturated steam autoclave sterilization for 30 minutes, the maximum working temperature of 60 degrees Celsius, good chemical stability, can withstand dilute acids, alcohols, esters, oils, hydrocarbons, halogenated Various organic and inorganic compounds such as hydrocarbons and organic oxides.
Uses: electronics, microelectronics, semiconductor industry water filtration, tissue culture media filtration, drug filtration, beverage filtration, high-purity chemical products filtration, filtration of aqueous solutions, and organic mobile phases.2) Mixed cellulose (MCE)
Features: Fast flow rate, high porosity, thin texture, low resistance.
Uses: MCE syringes filter is a Water syringes in the pharmaceutical industry that require autoclaving, large infusions to filter out particles; for sterilization of heat-sensitive drugs (insulin ATP, coenzyme A, and other biochemical agents), 0.45 or 0.22 micron filter membrane will be used.3) Polytetrafluoroethylene (PTFE)
Features: PTFE syringe filter has extensive chemical compatibility, filtering chemically corrosive organic solvents, aqueous solutions, and gases, and can withstand most strong acid and alkaline solutions. It can withstand strong solvents such as DMSO, THF, DMF, and dichloromethane.
Uses: Clarification and filtration of strong acids and alkalis; filtration of high-temperature liquids and special chemical reagents; Clarification and filtration of air or various gases.4) Polyvinylidene fluoride (PVDF)
Features: The protein binding rate of polyvinylidene fluoride membrane is far less than that of nitrocellulose, polytetrafluoroethylene, and other filtration membranes. It is compatible with a variety of organic solvents, has wide applicability, good oxidation resistance and heat resistance, and is applicable Used in HPLC, GC, and other sample preparation and solvent filtration.
Uses: Alcohols, acids, alkanes, aromatic hydrocarbons, halogenated hydrocarbons, and other solvents remove particles and improve the reagent level; Purification of particles in the air and sterilization of air in the fermentation industry; Purification of insoluble matter in oil and gravimetric analysis of solid particles; Separation and purification of non-specific proteins; Concentration of aqueous solution, separation, and recovery of chemical substances.