Characteristics and Applications of Several Commonly Used Filter Membranes

Introduction to HPLC disposable syringe filters

1. The housing of the HPLC disposable syringe filter is made of polycarbonate, polypropylene, polyethylene plastic, the upper and lower parts are welded together by ultrasonic, high pressure resistance, and no product leakage problems.

2. HPLC disposable syringe filter is widely used in laboratories. It does not require membrane replacement and filter cleaning, which saves complicated and time-consuming preparation work. It is mainly used for sample prefiltration, clarification and removal of particles, and sterilization and filtration of liquids and gases. Syringe filters are the preferred method for filtering small samples of HPLC and GC.

Classification of HPLC disposable syringe filters

1. Liquid property classification: water phase filtration; organic phase filtration.
2. Filter phase classification: gas phase filtration; liquid phase filtration.
3. Filtration purpose or process classification: sterilization filtration; clarification filtration; pre-filtration; particle removal filtration.
4. Interface form: female Luer lock; male Luer unlock.
5. Dimensions: 13mm, 25mm.
6. Hydrophobic polytetrafluoroethylene membrane (PTFE): used for filtration of air, gas and hydrophobic chemicals. HPLC Disposable Syringe

Selection of filter membrane for syringe filters to first consider is chemical compatibility, that is, whether the filter membrane is resistant to acids, alkalis, organic solvents, etc. For details, please refer to (attachment sheet) chemical compatibility table.

1. The pore size of the filter membrane for syringe filters:

* Pore size 0.45μm filter membrane: used for the mobile phase filtration of general samples, which can meet the general chromatographic requirements. For example: Chromatographic system for 3μm or larger particle size packing.

* Pore size 0.22μm membrane: it can remove the requirements of ultrafine particles in the sample and mobile phase. Such as: for chromatography systems with <3μm packing.

* Pore size 1-5μm filter membrane: commonly used in difficult to handle turbid solution, can be pre-filtered with 1-5μm filter membrane, and then use the corresponding filter membrane and then filter.

2. Characteristics of filtered samples for syringe filters:

A: Hydrophilic samples: Suitable for use with hydrophilic membranes, suitable for filtering water-based solutions. Such as: tap water, surface water, available filter membranes: water-based membrane (mixed cellulose ester), nylon membrane (polyamide).

B: For organic and inorganic compounds (alcohols, esters, oils), nylon films (polyamides) are suitable.

C: Protein solution sample: filter membrane suitable for low protein adsorption. That is, PVDF film.

D: Strong acid and alkali samples are suitable for hydrophobic PTFE (polytetrafluoroethylene membrane).

Selection of syringe filters:

* Case: High-pressure polypropylene (PP) is resistant to high temperatures, does not leak, does not require membrane replacement and cleaning, and saves complicated and time-consuming preparation work. It is the first choice for filtering HPLC and GC small samples.
* Selection of filter specifications: Φ13mm and Φ25mm are commonly used, that is, Φ13mm is used for sample size 2-10ml, and Φ25mm is used for sample size 10-100ml.
Glass Fiber Syringe FiltersHydrophobic PVDF Syringe FiltersSterile PES Syringe Filters

Characteristics and applications of several commonly used membranes:

1. Cellulose Acetate

Features: uniform pore size, high porosity, no medium shedding, thin texture, small resistance, fast filtration speed, low cost, but not resistant to organic solutions and strong acids and alkalis.

Applications: drinking water, surface water, well water, etc., sterilization filtration, analysis of particles and oil insolubles in solution, determination of water pollution index, filtration of particles and bacteria such as gas, oil, beverage, wine, etc. CA syringe filter is one of the most widely used filters in sample pretreatment filtration.

2. Nylon membrane (polyamide NYLON)

Nylon membrane has very good mechanical strength, strong adsorption, can withstand most organic solvents and most alkaline solutions, and is especially suitable for the filtration of alkaline solutions. For organic solvent filtration, such as HPLC mobile phase particle removal filtration, nylon membrane is more economical and practical than PTFE membrane. In addition, nylon membrane can also be used as a transfer membrane. Features: Good temperature resistance, can withstand 121 °C, saturated steam autoclaving for 30 minutes, maximum working temperature of 60 °C, good chemical stability, resistance to many organic and inorganic compounds and solvents such as dilute acid and alkali.
Application: Suitable for water filtration in electronics, microelectronics, semiconductor industry, tissue culture medium, medicinal solution, beverage, high-purity chemical, water and organic solution mobile phase. Nylon syringe filters used to filter alkaline solutions and organic solvents.

Due to the relatively high adsorption performance of nylon membranes, it is generally not recommended to filter biological samples such as culture media or protein liquids to avoid loss of samples due to adsorption. In this case, usually a low-adsorption cellulose acetate membrane (CA) is more suitable.

3. PVDF membrane (polyvinylidene fluoride)

PVDF membrane has excellent heat resistance and chemical stability. It is not corroded by acids, alkalis, strong oxidants and halogens at room temperature, and is stable to organic solvents such as aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, and aldehydes. Hydrophilic PVDF is widely used in sterilization filtration in biopharmaceuticals due to its low protein adsorption capacity. Positively charged PVDF can be used to remove endotoxins.

Features: The membrane has high mechanical strength, good tensile strength, good heat resistance and chemical stability, extremely low protein adsorption, and strong hydrophobicity.
Applications: PVDF syringe filter can used for gas and steam filtration, high temperature liquid filtration, sterilization filtration of tissue culture media, additives, etc., solvent and chemical raw material purification filtration.

4. PTFE membrane (polytetrafluoroethylene)

The PTFE membrane is made of PTFE, which is completely natural and permanently hydrophobic. Even at a very low pressure difference, it can ensure the passage of moist air or other gases without obstruction, while the aqueous solution cannot pass through. Its performance is just the opposite of that of the hydrophilic membrane. The PTFE membrane has strong chemical compatibility, and it can filter almost all organic solvents and strong corrosive chemicals. When the aqueous solution must be filtered with a PTFE membrane, it must be pre-soaked with ethanol or isopropanol before the aqueous solution can be filtered. Features: Has a wide range of chemical compatibility, good temperature resistance, strong acid and alkali resistance, strong chemically corrosive solvents and oxidants.
Applications: PTFE syringe filter can used for Chemical, pharmaceutical, environmental protection, electronics, food, energy and other fields, can filter almost all organic solutions.

4. The thermal spray fiber flat film PP is divided into isotactic and atactic polypropylene due to the difference in the spatial arrangement of molecular chains. At room temperature, it can withstand most chemical solvents except strong oxidants; it is used for impurities or particles in liquids or gases. Not as a sterilization filtration, only for clarification filtration.

2. Glass fiber pre-filter membrane (GF): PVDF syringe filter used to improve the filtration rate and continuous filtration; glass fiber filter membrane belongs to deep-layer filtration, and its main purpose is to be used as a pre-filter layer and directly added to the filter membrane.

HPLC disposable syringe filter application

1. HPLC sample preparation
2. Routine QC analysis
3. Remove protein deposits
4. Dissolution measurement
5. Food Analysis
6. Biofuel analysis
7. Environmental testing