High Quality Filtering Solutions
The main source of particle contamination in HPLC columns originate in the sample to be analysed. Therefore, the final preparation step prior to sample injection into the HPLC instrument is to remove any small particulates from the sample by filtration. Removal of the solid materials is very important as they can interfere with the compound of interest and easily clog up the column being used. This will inevitably have a detrimental effect on the performance of the column, i.e. back pressure, peak size, retention time, peak shape. Severe contamination can lead to the column being irreversibly blocked and therefore having to be replaced. Other costs can include instrument downtime, and the loss of valuable samples.
Samples differ in a variety of ways, they may be heavily loaded with fine or coarse particulates, dissolved in aqueous or organic solvents with varying viscosities. To facilitate the most appropriate sample preparation result, filters should be optimised to match the particular requirements of each kind of sample being injected.
A matrix of 5-10mL is the most common sample volume, with low viscosity, low particle contamination and dissolved in either an organic or an aqueous solvent. Greyhound Q-Fil Regenerated Cellulose Syringe Filters are an excellent choice for such samples. Their inert housing manufactured from high density medical grade virgin polypropylene, complete with the integrated Regenerated Cellulose (RC) membrane has a high chemical resistance against the most common HPLC solvents and is very suitable for aqueous samples. Every batch is HPLC-tested for low extractables. Whilst 0.45µm is the most commonly used membrane porosity, the 0.22µm membrane provides improved purity when using capillary columns or HPLC packings with a particle size of 3µm or less
More difficult samples which contain high loads of particulates, high viscosity or unusually high volumes place additional challenges on the user when preparing samples for HPLC analysis. The particles have a tendency to block the filter, high viscosities will decrease the flow rate and high volumes increase the time required to complete the filtration process. These challenges often result in the user applying a greater degree of manual pressure to the process and potentially exceeding the maximum pressure limit of the filter with a subsequent risk of bursting the housing. As a result, the sample will be lost and a potential safety risk can arise if corrosive solvents or harmful chemicals are being filtered. To assist in overcoming these challenges, the use of Q-Fil Syringe Filters with a built in Glass Microfiber pre-filter are recommended. The pre-filter removes the larger particulates from the sample leaving only the smaller particulates to be filtered by the membrane. These filters increase the flow rate through the unit resulting in a higher volume of sample to be filtered and less pressure being required by the user.
Small Volume Samples
Smaller volume samples are often valuable and require special attention. Any loss of the analyte due to adsorption by the filter membrane or housing or a large dead volume can have a detrimental effect on the analysis. Smaller filters of 13mm and 4mm diameter decrease the dead volume to less than 25uL and 8uL respectively making them ideal for smaller volume samples.
Sample filtration is an important factor in ensuring that HPLC analysis is achieved in an efficient and cost-effective way. The extensive range of Q-Fil Syringe Filters have been developed to meet the demands of the analyst and the different sample matrices being used and without losing any of the important sample.
Quality is an Important Factor
Greyhound ensures that every batch of filters is manufactured and tested in accordance with strict ISO 9001:2000 quality procedures.
Greyhound ensures that each batch is checked prior to release for:
- External Dimensions
- Bubble Point
- Water Flow Rate
- UV Extractables
- Burst Pressure and compliance - Filter Integrity.
Choosing a filter on price against quality is not cost effective in the long run. Although higher spec filters may seem expensive it is false economy to choose cheaper filters as their fail rate is much higher, causing delays in the laboratory.
Q-Fil Syringe Filters
How to choose the right syringe filter for your application
- Choose the size of filter based on the volume of sample to be filtered
- Choose the filters porosity based on the size of the potential particulates in the sample. It is important to be aware that the finer the porosity of the membrane the greater the pressure will be required to pass the sample through the filter. A sample containing large quantities of particulates is best filtered using a filter with a built-in glass microfiber pre-filter
- Choose the type of membrane based on the solvent being filtered
Q-Fil Syringe Filters are available in 0.22µm and 0.45µm pore sizes, (other pore sizes are available on request). The 0.22µm filters remove the smallest particulates whilst the 0.45µm filters are designed to remove particulates which would be detrimental to most analytical columns.
Pre-filters have a glass microfiber membrane which is chemically inert and resists most solvents. Q-Fil glass microfiber pre-filters are recommended for removing large particulates from the sample and are ideal for dissolution tests.
Syringe Filters with Glass Microfiber Pre-Filter
- The glass microfiber pre-filter is mounted before the microporous filter membrane, eliminating the need for a pre-filtration step, minimising sample loss and prolonging the life of the filter membrane
- These filters have the same high-quality filter membranes and polypropylene housings as our other Q-Fil Syringe Filters, but include a Glass Microfiber (GMF) membrane used as a pre-filter
- Flow rates are increased and the filtrate volume is significantly greater when compared to filters without pre-filters
- Regenerated Cellulose membrane filters with the GMF membrane incorporated as a pre-filter, are particularly useful for tissue culture media filtration, as well as for general biological sample filtration
- These filters are ideal for general laboratory filtration of samples which contain excessive amounts of particulates
- The glass microfiber pre-filter removes the large particulates and prevents premature clogging of the filter membrane
Greyhound Q-Fil Membrane Filters
Q-Fil Membrane Filters set the new Quality standard for today’s analytical laboratories. Manufactured from the highest quality materials, Q-Fil Membrane Filters provide excellent chemical compatibility with acids, alcohols, bases, ethers, glycols, ketones and oils.
As a trusted name in the supply of chromatography consumables and certified reference standards, Greyhound also offers a comprehensive selection of top quality own brand products including Capillary columns HPLC columns, Syringe Filters, Consumables etc. This catalogue contains details of our range of Q-Fil Membrane Filters. Other product catalogues are available on request.
|These quality products are backed by the guaranteed reliability and technical support which has become synonymous with the name Greyhound.|
Membrane Filter Comparison Chart
Full details and part numbers can be found in the Q-Fil Membrane Filters Catalogue above.
Tel: +44 (0) 151 649 4000
You may also be interested in