How To Choose a Syringe Filter

Choose Chrom Tech economical HPLC syringe filters to remove particulates from your liquid samples prior to injection on your HPLC. Our syringe filters are economical and designed to be single-use for your convenience and for laboratory efficiency. When choosing a syringe filter, three main factors dictate your syringe filter selection: sample volume, potential particulate size, and filter membrane compatibility.

Diameter of the Syringe Filter and Sample Volume

Sample volume dictates the diameter of the syringe filter. Intuitively, larger diameter syringe filters (e.g., 30mm syringe filters) filter larger sample sizes because of their wide cross-sectional membrane area, which offers increased filtration speed over the smaller diameter filters. Chrom Tech’s 30mm syringe filters can be chosen for filter samples less than 200mL.

13mm syringe filters are a popular choice for most chromatography methods and typically chosen when sample volume is less than 10mL.

Syringe Filter Pore Size

Two porosities of membranes are available for our syringe filters, 0.45 micron and 0.2 micron. The 0.45 micron pore is recommended to protect most HPLC instrumentation and columns from detrimental particulates. The newer trend is for chromatographers to develop assays with lower levels of detection, which in turn leads to columns of smaller particle size and the HPLC tubing internal diameter to get smaller and smaller. This trend to go smaller means that chromatographers need to filter their samples to remove even smaller particles; therefore, in these scenarios, it is recommended to use the 0.2 micron pore size syringe filter.

Syringe Filter Membrane Options

Chrom Tech stocks the most common membrane types to cover a wide range of applications. The main selection criteria for your syringe filter membrane is solvent compatibility and application (specifically, if you are concerned with protein binding).

Nylon membranes are used for general laboratory filtration of HPLC samples prior to injection. Nylon is solvent resistant, exhibits lows extractables, and is compatible with both aqueous and organic solvents. Nylon binds protein and should not be used when protein recovery is important. Nylon syringe filters have a blue color-coded ring around the housing body for easy identification.

PTFE is hydrophobic (therefore, cannot be used with aqueous samples) and chemically resistant to all solvents, acids, and bases. PTFE does not impart extractables to the filtrate. PTFE syringe filters have a red color-coded ring around the housing body for easy identification.

PVDF (polyvinylidene difluoride) is a solvent-resistant membrane that exhibits low levels of UV-adsorbing extractables and is recommended for HPLC sample filtration and general biological filtration. PVDF is a low-protein binding membrane and compatible with both aqueous and organic solvents. PVDF syringe filters have a yellow color-coded ring around the housing body for easy identification.

PES (polyethersulfone) is a mechanically strong membrane low in inorganic extractable ions. Typical applications include ion chromatography, tissue culture filtration, and filtration of proteins and nucleic acids. PES is a low-protein binding membrane and compatible with both aqueous and organic solvents. PES syringe filters have a green color-coded ring around the housing body for easy identification.

CA (cellulose acetate) is a very low-protein binding membrane (binds less protein than PVDF) and is ideal for aqueous-based samples. CA is not compatible with organic solvents. CA membranes are an excellent choice when maximum protein recovery in filtrate is critical. CA syringe filters have an orange color-coded ring around the housing body for easy identification.

PP (polypropylene) is a hydrophilic membrane that exhibits a wide range of chemical compatibility to organic solvents. PP syringe filters have a purple color-coded ring around the housing body for easy identification.

Other Questions Related To Syringe Filters

How Do I Use a Syringe Filter?

Syringe filters are made from a virgin polypropylene housing with a female luer lock inlet and a male slip luer outlet. To use syringe filters, the sample is loaded into a disposable luer syringe. The syringe is then attached to the female luer portion of the syringe filter by securely fastening with a twisting motion. It is important to hold the assembled syringe and filter vertically to ensure the sample is spread evenly over the membrane surface. This promotes a good flow rate and minimizes the back pressure. While depressing the plunger, if the back pressure significantly increases, you could have a plugged syringe filter or an incompatible membrane. Either way, you want to avoid excess pressure, as that could cause the housing or membrane to burst. If you suspect a plugged syringe filter, dispose of the syringe filter and get new syringe filter. If it is the first time using the specific syringe filter membrane with your sample/solvent combination, you may have an incompatible membrane. For example, a PTFE membrane is hydrophobic, therefore, if you have an aqueous sample, it will not be compatible, and will cause excessive pressure and will burst the membrane or housing.

What Else Could I Use To Filter My Sample?

Traditionally, scientists used a Buchner funnel with individual cut membrane filters. Although this is still used with large sample volumes, today’s disposable syringe filters are much more efficient for routine HPLC analysis.

In addition to syringe filters for removing particulates from your sample, Chrom Tech also offers syringeless filter vials. These filter vials are an all-in-one design; simply deposit the sample into the vial, and the plunger filter membrane nestles into the vial while simultaneously filtering and readying the sample for the HPLC autosampler. This is a single-step process that minimizes any loss of sample.

Chrom Tech also offers filter membranes in centrifuge tubes (Chrom Tech Centrifuge Filters) and 96 well Filter plates (Chrom Tech 96 Well Filter Plates) in a variety of membranes. 96 well plates are used in high-throughput labs that require automation for efficiency.

Summary

Please contact Chrom Tech at support@chromtech.com to help you select the correct syringe filter membrane for your application. Chrom Tech syringe filters are color-coded based on the filter membrane; therefore, if you keep multiple types of syringe filters in the lab, you can easily tell you have the correct membrane for your method. Chrom Tech syringe filters are a common chromatography consumable to have in the lab for analytical testing. Using syringe filters can protect your HPLC instrumentation from harmful particulates and help you maximize your instruments’ uptime.