Yes, if you are wiling to introduce Methanol into your Method. For a 25mm syringe filter device; if you use 15-20mls of Methanol as a blank Filtrate, the Membrane will give you less back pressure after that for Aqueous samples. This “conversion” is due to “wetting” the Membrane with Methanol allowing more Aqueous Solvents to […]
Category: Syringe Filters and Filtration
Filtering Proteins, which Membrane to Use.
Filters should not remove Proteins or any other dissolved Compounds from a solution. Proper filters have one purpose and that is to remove un-Dissolved particles no matter what they are. Some Filters, depending on the Membrane type and specifications, will adsorb Compounds such as Proteins to the Membrane but if the Solutions is Analyte abundant, […]
How to Use Bubble Point to Filter Water through Hydrophobic Membranes.
Bubble Point pressure is the differential pressure required for a liquid to flow through a dry filter membrane. The differential pressure is either a positive pressure on the liquid layer on top of the membrane or a vacuum applied below the membrane or a combination of the two. The bubble point pressure is determined by […]
I See Extra Peaks in my Data and Sometimes I am not Using the Same Filter. Suggestions? FAQ
Yes, “Best Practices” for using any Syringe Filter is to dispose of the first few milliliters that comes through the Filter. If there are any Extractables or if there is going to be any adsorption to the Membrane, it will usually happen in the first few milliliters. This is called bringing the filter to a […]
Ideas on Pressure Increases after Each HPLC Injection – Tip
Question: I am injecting cell extract samples on my HPLC instrument and I find that the back pressure increases after each run. Any ideas on what the problem might be? Answer: There are a number of possible causes. First, always be sure to sonicate and filter your mobile phase before introducing to the LC system especially […]
Protecting HPLC Analytical Columns: When to use Guard Columns vs. Cogent Column Filters. – Tips
All filters including an In line filter such as a pre-column, Cogent Column Filter are designed solely for preventing non-dissolved particulate matter from reaching the analytical column or the HPLC instrument. Note that the analytical column does have porous frits on the inlet (and outlet) that will also prevent some un-dissolved material or shredded pieces […]
Should I filter my HPLC Solvents and Buffers before use? – FAQ
The most common cause of excessive back pressure is due to the accumulation of particulates and or permanently adsorbed materials at the top of the HPLC Column. This could be precipitate or un-dissolved particles which can come from your samples or your mobile phase or shredded pieces of pump seals. The best way to minimize […]
Spurious Peaks from Nylon Syringe Filters with DI Water using Electrochemical Detection can be avoided.
When using Electrochemical Detection, spurious Peaks in your Chromatogram may be observed if a Nylon Syringe Filter is used with a DI Water solvent. The anionic peaks are most likely Nitrate Extractable and therefore we recommend using Polyester Sulfone (PES) Syringe Filters instead. This membrane type is suited to situations when you want to avoid nitrate […]
What are the Differences between Nylon and PTFE Filters for my Filtration Application? FAQ
There is a bit of a misconception in the field regarding PTFE v. Nylon Membranes for Filtration using Syringe Filter Devices and which Membrane can be used with different solutions and or solvents. PTFE as a Membrane for Syringe Filters is considered to be more “chemically resistant” and Nylon to be the most “extractable free” […]
What is a “Steady State” for Surfaces like Syringe Filters? FAQ
A Filter could have charged sites on it or a small amount of Extractables. Most manufacturers, including MicroSolv, produce Filters with the lowest Extractables possible. If these Extractables are soluble in the Solvent you are using, you should see them only in the first few milliliters. This aliquot should be discarded. If your Filter has […]
What is an Extractable that comes from Syringe Filters? FAQ
An Extractable from a Syringe Filter or any device for that matter, is any Chemical that is present in your Sample after Filtering that was not there before and the source is the Filter. These Extractables can be from the material itself such as threads or can be from the manufacturing process. No matter the […]
What is the difference between AQ™ brand and low cost syringe filter brands?
AQ™ syringe filters are made to a higher standard of quality such as extractables, adsorption, flow design and have a 3 piece leak proof plastic device. AQ™ filters are supplied with CofA for HPLC and Dissolution testing. They cost more but bring a “Consistency Insurance”. These filters have bright colored rings for ease of identification. For […]
Which Filter Membrane is best for Aqueous Buffers? FAQ
The “Best Membrane” is a difficult Question to answer as it depends on your Sample that you are Filtering and the Solvent is it dissolved in. For most HPLC and Dissolution testing, Hydrophilic Nylon Membranes are generally used because they are durable, compatible with most Aqueous Solvents including Water and have the lowest Extractables with […]
Why is Nylon called Nylon? FAQ
According to the “Answers Corporation” website, nylon was developed at both New York and London, simultaneously. However, it has also been stated that the letters “nyl” were arbitrary and the “on” was copied from the suffixes of other fibers such as cotton and Rayon. A later publication by DuPont (Context, vol. 7, no. 2, 1978) […]
Will I Protect my HPLC Columns from Samples that Permanently Adsorb to them by using a Syringe Filter? FAQ
No, some lab people get confused on the purpose of Syringe Filters. They are not Chemical Filters, only Particulate Filters and only remove un-dissolved Particles from your Samples. If anything is dissolved in your Solvent, and once the Filter is at a Steady State, it will not Adsorb anything. It will only Exclude Particles that […]