Syringe filters are single-use, membrane-based equipment. They are ideal for eliminating particle contaminants from tiny liquid and gas samples.
In this article, find out about the appropriate material and size of the syringe filter. Additionally, discover how to choose the perfect syringe. As well as the difference between sterile and non-sterile syringes.
Which material should you use for a syringe filter?
There are many materials you can choose from. Here are some of the most common ones:
Cellulose Acetate(CA)
Cellulose acetate (CA) has an excellent flow rate. Yet, they have a limited protein binding capacity. Besides, a little protein is making them ideal for protein recovery applications.
Although they have weak solvent resistance, they are hydrophilic. Since the material is hydrophilic, it is ideal for aqueous and alcoholic media. CA has a pH range of 4 to 8.
Some of the characteristics are:
Rapid mechanical strength, high flow rates, and low extractable levels characterize cellulose nitrate. As a result, it’s a fantastic choice for trace element analysis. Protein binding is high. It also has a pH range of 4 to 8.
Regenerated Cellulose (RC)
Regenerated cellulose (RC) is cellulose renewed without any wetting agents. Resistant to a wide range of solvents chemically.
Also, the cellulose’s wet strength is high. Because it is hydrophilic, it suits both aqueous and organic samples. But, protein binding ability is relatively poor. pH levels vary from 3 to 12.
Glass Microfibre Filter (GMF)
GMF is a chemically inert membrane with larger pore diameters than conventional membranes. As a result, GMF is robust mechanically and resistant to organic solvents.
Strong acids (especially hydrofluoric acid) and bases are not recommended. But, strong acids are often used as a pre-filter. Before a membrane filter for high particle solutions.
There is one thing about GMF. It has lower precise retention effectiveness than membrane filters.
Nylon
Nylon is a hydrophilic, flexible, tear-resistant, and autoclavable membrane filter. They can withstand a variety of organic solvents and are excellent for high pH samples. The protein binds nylon. Acidic solutions are not recommended; the pH range is 3-14.
Polyethersulfones (PES)
Polyethersulfones (PES) is a material for a wide range of aqueous and organic solvents. It is hydrophilic, stable at low pH, low in extractable, and has a low protein binding.
PES membranes have a greater liquid flow rate than PTFE membranes. Thus, it can withstand extreme temperatures. A pH range of 3 to 14 (sometimes quoted as 1-14).
Polypropylene (PP)
Polypropylene (PP) is a hydrophobic material. You can use it with a broad range of solvents. Use it even with aggressive solvents, with difficult-to-filter solutions like extremely acidic samples.
Tolerance to heat and mechanical stress is high and consistent. It has a pH range of approx. 1-14.
Polyvinylidene Fluoride (PVDF)
Polyvinylidene fluoride (PVDF) has:
1. High tensile strength,
2. Strong solvent resistance,
3. Low protein binding,
Which makes it ideal for biomedical filtering, sterilizing filtration, and HPLC sample preparation. pH levels vary from 1 to 14.
Polytetrafluoroethylene (PTFE)
PTFE is ideal for filtering gaseous or organic solvent-based samples and corrosive metals.
Because it’s hydrophobic, it’s resistant to hostile media. It also has excellent temperature stability, allowing for a broader sample range.
When working with watery materials, the membrane generally has to be pre-wetted. You can wet the membrane with a small amount of alcohol. You may also use it to keep moisture out of air vents. pH levels vary from 1 to 14.
Hydrophilic PVDF and PTFE
We talked about the hydrophobic PTFE and PVDF above.
The hydrophobic type of syringe filter is generally used for gas filtration.
If we use hydrophilic type PTFE or PVDF, it means we need to apply it to filtration of liquids (organic solvents, strong acids, alkalis, and aqueous solutions).
It is also possible to filter organic solvents using hydrophobic membranes, such as ethanol, etc. As a general rule, liquids that can be filtered with a hydrophobic type can also be filtered with a hydrophilic type. So, hydrophilic filters are recommended for filtration of liquids.
Which Size of a Syringe Filter Should You Use?
It would be best to look at a few things when choosing the right syringe filter.
The majority of syringe filters come in a variety of pore diameters. So, it’s critical to ensure the pore size is right for your application to work.
Below are the most frequent pore sizes found, as well as samples of typical uses:
0.1m – mycoplasma elimination and solution sterilization
0.2/0.22m – sterilization of the solution (bacterial removal)
0.45m – filtration and particle reduction in general
>0.45m – often used as a pre-filter
Next, choose a proper diameter.
The total amount you can filter via a given diameter syringe filter can vary. That is because high particulate-loaded samples tend to clog membrane pores faster.
For samples of less than 10ml, use a 13mm diameter tube.
For models of less than 100ml, use a 25mm diameter tube.
For pieces of less than 250ml, use a 33mm diameter tube.
Step-by-Step Guide on How to Choose a Syringe Filter
Here is a quick guide on choosing the right filter for your syringe.
1. Step – Determine if Your Application Requires Pre-Filtration
Prefiltration is often known as screening or coarse filtration. It is a method of removing big particles and waste from membrane filtration systems.
You can use prefiltration on the entire membrane filtration system. You can use it also on individual membrane units.
The pore size used in the prefiltration process varies based on:
1. The kind of membrane filter system used
2. The quality of the input water.
2. Step – Select an Appropriate Membrane Type
Here is a quick guide on selecting a proper membrane-type made by airekacells.
Source: airkacells
3. Step – Select an Appropriate Filter Diameter
Filter inlets come in three sizes. Also, they are female Luer-Lock suitable and feature inert polypropylene housings. The diameter determines the volume, which you can filter.
You can choose between 13, 25, and 33mm filter diameters, as explained above.
4. Step – Now, Select a Proper Pore Size
For research and medical purposes, 0.2/0.22 μ and 0.45 μ syringe filters are the most often used pore sizes.
The particle size determines the pore size you use. For example, use a syringe filter of 0.2-micron pore size to filter out particles larger than 0.2 microns in diameter.
Another method for determining column micron size:
– use 0.45 μ for microns greater than 3 μ
– use 0.22 μ for microns less than 3 μ
0.45 μ membranes:
– for filtering and particle removal
0.22 μ membranes:
– for solution sterility (bacteria removal)
5. Step – Is it Better to Have a Sterile or Non-Sterile Syringe Filter?
Check below for details on sterile and non-sterile syringe filters.
You can use sterile or non-sterile syringe filters for particulates removal. Make the decision based on the following operating applications:
– If you need a sterilized solution, use a sterile syringe filter. Those filters often come separately packed. They provide the most excellent performance without contamination.
– Use a non-sterile needle filter if you plan to sterilize the solution. Non-sterile filters are much cheaper.
Let’s talk more about sterile and non-sterile syringe filters.
Sterile and Non-Sterile Syringe Filters
You can find a sterile filter at the end of a syringe. That filter removes all particles from a sample before the examination.
Scientists use testing applications in a variety of industries, such as:
1. Pharmaceutical industry
2. Biotechnology industry
3. Agricultural laboratories
So, in analysis, non-sterile syringe filters can help you get the most out of your equipment.
1. UHPLC,
2. LC-MS
3. Ion chromatography
4. Dissolution testing
In Which Cases Do You Use a Sterile Syringe Filter in General?
Use a sterile syringe filter for sterilizing liquids or purifying sterilized solutions.
What is the Application of the Sterile Syringe Filter
The sterile syringe filter is primarily used for:
1. Sample pre-clarification,
2. Particle removal,
3. Liquid and gas sterilization filtering,
4. Laboratory biological fluid,
5. Culture medium and medium additives sterilization filtration,
6. Other similar applications.
So, what is the application of the sterile syringe filter?
1. Analyze the ambient air quality, exhaust gases, and water.
2. To filter out particles, the medical business requires:
a) Autoclave sterilization water injection
b) Effective infusion solution.
It can increase the internal quality of medications and the clarity pass rate.
3. Detection and analysis of:
a) Food,
b) Beverage,
c) Medicinal raw materials,
d) Completed goods
f) Semi-finished products.
4. Filtration of water and organic solutions in educational and commercial R&D laboratories.
5. Sample preparation for chromatography and mass spectrometry; teaching, quality inspection, and quality control
How Long do Syringes Stay Sterile?
A typical syringe filled with medication is sterile for about 12 hours.
When Should You Use a Non-Sterile Syringe Filter?
Use a non-sterilized syringe filter for routine filtering and sample purification.
You can use non-sterile syringe filters for:
- Pre-filtration
- General filtration
- Analytical sample preparation applications
How to Use a Syringe Filter? Step-by-Step Guide
1. Fill the syringe with the sample.
2. Using a twisting motion, secure the filter. This is roughly one-quarter turn with a Luer slip syringe as the filter is pressed. If the needle has a Luer lock (as in this case), tighten it but not too much.
3. Hold the syringe upright and filter vertically to moisten the membrane. Avoid air obstructions by dispersing the sample throughout the membrane surface.
4. Press the syringe plunger to pass the sample through the filter.
If possible, drop the first 0.25-0.5ml of the sample. Since any contamination will most likely be in the first few microlitres. Replace the filter if the backpressure rises since it may have clogged. Excessive pressure might cause the filter housing to burst, so be careful.
5. Change the filter and repeat the process for the following sample.
“Air-Purge”
If you have a small sample, you can decrease the loss in the syringe by using the “air-purge” approach.
Before filling the syringe with the sample solution, pull a little quantity of air into it. Use this air to purge the filter, ensuring that only the tiniest amount of sample remains in the filter.
Contamination
If you’re concerned about contamination, syringe filters can cause contamination at low levels.
Before filtering the sample through the same filter, wash it with ultra-clean water. Or wash it with a mild (1 percent) acid solution to limit the quantity of contamination.
You may need to repeat this process several times to thoroughly “clean” the filter.
What to Look Out for When Using Syringe Filters?
1. Cleanse the new syringe filter to avoid contamination. Cleanse it with detergent, sterilize it, disinfect, and clean it with high-temperature steam.
2. Before using the syringe filter, ensure the attachments and the sealing ring are present and undamaged. Install it as needed.
3. The cylinder’s pressure gauge is a liquid pressure display gauge. Thus, using a secondary filter allows the syringe filter pressure gauge index to be lower.
The pressure will rise, and the flow rate will fall as the filter’s time increases. That indicates that the majority of the holes in the filter element have been plugged. That means you need to flush them or replace them with a new filter element.
4. Do not connect the inlet and outlet of the syringe filter backward while installing it.
The clean liquid output port links to the filter element socket. The liquid inlet port is on the pipe filter bottom plate side.
5. Make sure the filter element is upright before placing it into the port. The pressure plate bends the fins and tightens the screws once you insert the port.
You should turn the filter element of the 226 interfaces 90 degrees and clamp it after the entrance. This is the most crucial step in the installation process.
If you’re not cautious, the seal won’t hold, and the water will leak, which won’t fulfill your needs.
6. The manufacturer packed the replacement filter element in a clean production facility. And in a plastic bag.
Before using, do not rip the plastic packaging. Instead, use a more demanding filter element. After installation, sterilize it with high-temperature steam.
7. When the liquid enters the syringe filter, turn on the vent switch to fill the cylinder with the liquid. Otherwise, the filtering effect will be poor.
Conclusion
In this article, we have already discussed the type of material, the size, and the appropriate use of syringe filters. For more details on the different kinds of syringe filters that Mastelf offers, Just CLICK here. Here, you can get everything you need.
