WHAT IS A Syringe FILTER?
A syringe filter (or wheel filter) is a single-use, membrane-based device used for the removal of particulate impurities from small (≤ 100 mL) liquid samples Selected based upon the desired end application, disposable Syringe Filters are commonly used in labs for fast and efficient filtering, material purification, or even sterilization.
Syringe filters are single-use, membrane-based devices used for the removal of particulate impurities from liquid and gas samples prior to analysis by methods such as HPLC, ion chromatography, gas chromatography, ICP, and dissolution testing. Proper filtration of samples improves the quality and consistency of analytical results and decreases instrument downtime.
Disposable syringe filters are commonly used for fast and efficient filtering. Selection should be by application. Sterile syringe filters are used to sterilize solutions or clarify sterile solutions, while nonsterile syringe filters are used for general filtration and sample purification.
How to use syringe filter
After selecting the appropriate syringe filter and syringe for your sample and application, draw your sample into the syringe and draw the sample.
Fix the filter securely with a twisting motion. With a Luer Slip syringe, this is about a quarter turn when the filter is pushed in. If the syringe has a luer lock, attach it firmly but do not overtighten.
Hold the syringe with the filter pointing up and “top off” by pushing a first 0.25-0.5ml of sample to remove the as if there is contamination present.
If the back pressure increases significantly, change the filter as it may have become clogged. Avoid pressing too hard as this may cause the filter housing to burst.
Place the filter tip over the collection container and push the sample through a syringe filter by applying gentle positive pressure.
To purge the syringe filter and maximize sample throughput, remove the filter from the syringe and draw air into the syringe. Then reattach the filter and push the plunger to force some of the air through the filter.
How to choose Syringe Filter
1. Match pore size with your application
Most types of syringe filters come in a selection of pore sizes. Ensuring the pore size is suitable for your application is highly important to ensure it functions as you desire. Below are the most common pore sizes found in our range and examples of typical applications.
· 0.1μm – solution sterilization and mycoplasma removal
· 0.2/0.22μm – solution sterilization (bacterial removal)
· 0.45μm – general filtration and particle removal
· >0.45μm – typically used for pre-filtration
2. Filter Materials
Syringe filters are composed of a membrane filter contained with plastic housing (usually polypropylene). Each membrane has a number of key physical and chemical characteristics that make it suited to a certain type of application.
Cellulose Acetate (CA): Excellent flow rates. Very low protein binding, so they are suitable for protein recovery applications. Hydrophilic, so fine for aqueous and alcoholic media although they have limited solvent resistance. A physically strong membrane which can be used with heated liquids. pH range ~4-8.
3. Select diameter based on your sample volume
Syringe filter size is determined by the size of your sample. In other words, the amount of volume you plan to push through the filter. As a general rule, use a syringe filter with a greater membrane area if you plan to push a high volume of aqueous solution through it. Syringe filters for aqueous solutions are available in diameters of: 4mm, 13mm, 17mm, 20mm, 25mm, 30mm, and 33mm. Here’s a guide to help you choose your syringe filter size:
4 mm filters – for small volume samples less than 1 ml
13 mm filters – for sample volumes between 1 and 10 ml
17 mm filters – for sample volumes greater than 10 ml
25 mm filters – for most applications, ideal for high throughput labs
30 mm filters – for large sample volumes greater than 100 ml
4. SELECT SYRINGE FITTING
Most syringe filters with come with the standardised Luer fitting – either Luer Lock or Luer Slip
Luer Slip – will fit on to any Luer fitting syringe. Simply ‘slip’ the filter onto the end of your syringe. It is quick to add and remove from the syringe
Luer Lock – will only fit onto a Luer Lock syringe. The filter locks into place and this allows for a greater pressure to used with the filter popping off like it would do on Luer slip.
Other syringe filters or inline filters may come with different types of fitting such as stepped barb
5. RETENTION VOLUME
The retention volume for 25mm filter is µL and for 15mm filter is 100 µL and 4 mm is less than 10 µL
6. STERILE OR NON-STERILE SYRINGE FILTERS
While the primary function of a syringe filter is to remove particulates from a liquid sample, you will select either a sterile or non-sterile filter, depending on the end application.
Sterile syringe filters are used to sterilize non-sterile solutions or clarify sterile solutions. Learn more about sterile filters by application.
Non-sterile syringe filters are used for general filtration and sample purification.
Based on the above paraments we can select the syringe filter.
7. Solvent Compatibility for syringe filter
This post first appeared on The Place To Find Pharmaceutical SOP, please read the originial post: here
