Syringe Filters for Ion Chromatography When using ion chromatography (IC) to separate ions and polar molecules, choosing the proper syringe filter is critical for ensuring that both particles and microorganisms are removed in the sample preparation process. Ion chromatography is relied on for so many uses, such as clinical applications, industrial applications, and pharmaceutical drug development. It is also used for water analysis, protein purification, filtration, distillation, adsorption, environmental concerns, quality control, and other ion analyses in the semiconductor, chemistry, and other fields. With such diverse applications, it’s often difficult to determine which type of ion chromatography syringe filters to use for sample preparation. Key considerations include: connection types, membrane material, pore size, the diameter of the filter based on your application, Additional considerations include the use of a prefilter for heavy particulate and whether the filter needs to be sterile and individually packaged. This article is designed to help you decide which syringe filters to use for ion chromatography. Connection Types Ion chromatography syringe filters typically feature a female luer lock inlet and male luer slip outlet. This double luer lock design ensures a tight and secure connection for in line applications. Membrane Material With ion chromatography, the type or chemistry of the solution being filtered through the syringe filter will impact its membrane material. This should be taken into consideration when deciding which syringe filter material to use. For example, some syringe filter membrane materials are high protein binding, while some are low protein binding. Others are hydrophobic or repel water, meaning water will not flow through them, while some are hydrophilic, or the opposite of hydrophobic. There are 15 syringe filter materials to choose from. To help you select the proper one for your application, the following list includes the type of filter membrane material, its characteristics and compatibility with solutions. Cellulose Acetate Cellulose Acetate is a hydrophilic membrane best for filtering biological samples or aqueous solutions, very low protein binding, excellent flow rates, can use with heated liquids, do not use with benzyl alcohol or organic solvents. Glass Fiber The membrane is best for filtering viscous samples or samples with large particulates. It exhibits good throughput but it is not to be used with benzyl alcohol. Another common application for this membrane is for prefiltering where the are a large amount of suspended solids present. Nylon Hydrophilic membrane best for analytical applications and preparing organic or aqueous samples, excellent flow rates, high throughput loading, and wide-ranging chemical resistance. Do not use with acids, aggressive halogenated hydrocarbons, or protein samples with high nonspecific binding properties. Polyethersulfone (PES) Certified for IC, best for dissolution testing applications, hydrophilic membrane, low protein binding, excellent flow rates, compatible with an extensive range of solvents, not for protein-based samples in aqueous solutions, do not use with concentrated acids, chloroform, esters, ketones, hexane, halogenated or aromatic hydrocarbons, chloromethane, and acetone. Polypropylene (PP) Good for biological samples and aqueous or organic samples, hydrophilic membrane, low protein binding, do not use with organic solvents, including aromatic or chlorinated solvents, benzene, hexane, and toluene. Polytetrafluoroethylene (PTFE) Good for general sample preparation and dissolution sample analysis. PTFE is naturally hydrophobic, however, treated hydrophilic PTFE is also available. PTFE has excellent flow rates, temperature stability and chemical resistance, high loading capacities, low protein binding, and hydrophilic PTFE can be used for aqueous, organic, or gaseous samples. Do not use with perchloric acid, dioxane, methylene chloride, formic acid if greater than 50 percent, and dimethylformamide (DMF). Polyvinylidene Fluoride (PVDF) Certified for chromatographic performance, best for high performance liquid chromatography (HPLC) and ultra high performance liquid chromatography (UHPLC), environmental water samples and protein based samples with high nonspecific binding. Can be used with most organic and aqueous solvents, low nonspecific binding, excellent chemical resistance, well-defined pore structure. PVDF is naturally hydrophobic, if using with aqueous solutions treated hydrophilic PVDF is also available. Do not use with most strong acids and caustic solutions, dimethylformamide (DMF), ketones, dimethyl sulfoxide, ethers, acetone, and esters. Regenerated cellulose (RC) Certified for high performance liquid chromatography (HPLC), ideal for most laboratory procedures, including biological sample recoveries and dissolution sample testing. Compatible with broad range of organic and aqueous samples, excellent flow rates and chemical resistance, hydrophilic membrane, very low protein binding, minimal extractables. Do not use with dimethylformamide (DMF), chloroform, sulfuric acid, nitric acid greater than 25 percent, phosphoric acid, hydrochloric acid, phenol, and tetrahydrofuran (THF). Anopore An inorganic membrane, manufactured by Whatman, fabricated from aluminum oxide and housed in polypropylene. This filter is ideal for a wide range of specialized filtration applications, use with organic and aqueous samples, handles 100 ml sample volumes, high flow rates and pore density, highly efficient particle retention, low protein binding, and low holdup volume. Do not use with hydrochloric acid, sulfuric acid, sodium hydroxide (NaOH), and ammonium hydroxide. Syringe filter material reference chart If you’re looking for: Then use: Certified for ion chromatography PES or PVDF Hydrophilic membrane CA, Nylon, PES, PP, or RC Hydrophobic membrane PTFE High performance liquid chromatography (HPLC) PVDF, Nylon, RC, PTFE, or Anopore Compatible with organic and aqueous samples Hydrophilic PTFE, Nylon, PP, PVDF, RC, or Anopore Compatible with water CA, Nylon, PES, or PTFE Compatible with gaseous samples Hydrophilic PTFE Organic compatibility RC, PTFE, or PVDF Low protein binding CA, PES, PP, RC, Anopore, or Hydrophilic PTFE Nonspecific binding Nylon, or PVDF Excellent flow rates CA, Nylon, PES, PTFE, PVDF, RC, or Anopore Large particulate removal Glass Fiber or Anopore Low extraction Glass Fiber High throughput loading Nylon, PTFE, or Anopore Biological sample preparation RC, CA, or PP Protein analysis PVDF High solid samples Glass Fiber Capillary electrophoresis PES Trace metals PES Pore Size With ion chromatography, the types and sizes of suspended particulate in your solution can impact the pore size of the syringe filter. For example, routine laboratory sterilization is commonly done with pore sizes of 0.2 or 0.22 µm. Other particulates range in size, so you need to know the types and sizes of particulate you need to remove or capture from your sample in order to choose the proper pore size for your syringe filter. Syringe filters for ion chromatography are available in 0.05 µm, 0.10 µm, 0.22 µm, 0.45 µm, 0.70 µm, 0.80 µm, 1 µm, 3 µm, 5 µm, and 10 µm pore sizes. If you need to extend the life of the filter or allow for increased flow during filter life, choose a syringe filter with a prefilter. Diameter The size of your syringe filter for ion chromatography needs to be able to handle your sample size. In terms of volume, the more you will be pushing through the filter, the more membrane area needed to filter the sample. The diameters of syringe filters are generally: 4mm, 13mm, 17mm, 20mm, 25mm, 30mm, and 33mm. Diameter largely affects cost and hold up volume. You want to choose the minimum diameter filter for your needs to keep costs down. Likewise, large diameters will increase hold up volume, wasting part of your sample. As a general guide, if your sample volume is greater than 2 ml, choose a 4mm diameter syringe filter. If your sample volume is greater than 10 ml, select a 17mm diameter syringe filter. For sample volumes greater than 100 ml, choose a 30mm syringe filter. Sterile or Nonsterile Whether you need a sterile or nonsterile syringe filter all depends on your ion chromatography application. Sterile filtration is typically necessary for clarifying or sterilizing biological solutions. Sterile syringe filters are wrapped individually and contain a shelf life expiration date. Nonsterile filtration is applicable for particle removal, clarification, or filtration from high performance liquid chromatography (HPLC) or gas chromatography (GC) solvents, reagents, buffers, etc. Still Have Questions? 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