Sample filtration is one of the important processes in pre-treatment, which aims to remove impurities and obtain fSample filtration is one of the important processes in pre-treatment, which aims to remove impurities and obtain filtrate to improve the accuracy of experiments and reduce the harm caused by solution particles to experimental equipment. As the most commonly used consumable for sample filtration in the laboratory, how to choose a suitable syringe filter is crucial. Choosing the wrong syringe filter can lead to prolonged experiment time, the need to repeat the process, and wasted effort.  
Today, the editor will take you through how to choose the appropriate syringe filter based on the characteristics of the sample.

1 Material

There are a variety of materials available on the market, and here the editor mainly lists the more common ones.


Mainly used for organic phase filtration, but can also filter aqueous solutions. Its characteristics are high flux, low extractables, and good mechanical strength. It is available in NY6 and NY66 materials and is resistant to weak acids and weak bases.

Polyethersulfone (PES)

Low protein binding, high flow rate, and wide pH range, mainly used for aqueous phase filtration.

Mixed Cellulose Esters (MCE)

Mainly used for aqueous phase filtration, with high protein binding capacity and a pH range that tends to be neutral. It is not resistant to strong acids and bases.

Polytetrafluoroethylene (PTFE), also known as Teflon, is a hydrophobic material used for filtering organic phases. Modified hydrophilic PTFE can filter both water and organic phases.

Polyvinylidene fluoride (PVDF) has low protein binding and is widely used due to its compatibility with aqueous and various organic solvents. It has good oxidation and heat resistance.

In addition to the above materials, Welch Materials also offers polypropylene (PP), glass fiber (GF), and cellulose acetate (CA).

2 Diameter

When it comes to diameter, the most commonly used specifications are 13mm and 25mm.

How to Choose Diameter?

Choose the corresponding diameter based on the volume of the sample:

● For sample volumes of 2~10mL, choose 13mm;

● For sample volumes of 10mL~100mL, choose 25mm;

● For sample volumes larger than 100mL, consider using 33mm.

3 Pore Size

When it comes to pore size, the main focus is on 0.22μm and 0.45μm, although Welch Materials also sells other non-standard specifications.

How to Choose Pore Size?

● A 0.22μm pore size can remove extremely fine particles in the sample and mobile phase and is suitable for chromatography systems with packing materials smaller than 3μm;

● A 0.45μm pore size is mainly used for filtering routine samples and mobile phases, and can meet general chromatography requirements for columns packed with 3μm or larger particles;

● For difficult-to-process turbid solutions, a pre-filter with a 1-5μm membrane can be used first, followed by continuous filtration with the appropriate membrane.

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