What should you pay attention to during sample preparation?

Sample filtration is a key step in preparing samples for chromatographic analysis. If the sample is not filtered before the experiment, problems such as column frit clogging will occur, resulting in increased back pressure and reduced column performance. , which will increase the time spent on troubleshooting and maintenance of the chromatograph, waste time and increase the workload of scientific researchers.

For most types of samples, filtration processing is relatively simple. Use the solvent inlet filter to filter the mobile phase before injection. This step is also very important. The chromatography filter head can effectively filter out solid particle impurities in the mobile phase; unfiltered solvents or microorganisms growing in solvent bottles will reduce the performance of the liquid chromatography column and pump. After a period of use, the solvent inlet filter needs to be cleaned or replaced regularly.

When analyzing in the food and beverage industry, some samples such as thick syrups, pulp juices and fats that are viscous or contain a large amount of particulate matter are difficult to filter. And if your sample contains ingredients such as cornstarch, syrup, soy, sucrose, or fruit additives, using a standard syringe filter can also be a challenge.

What should you pay attention to when filtering viscous samples? When pushing a viscous sample through a syringe filter by hand, you need to push hard by hand and use multiple syringes, which reduces efficiency; the pump pressure may need to be increased due to clogging of the glass frit; shoulder peaks or split chromatographic peaks are prone to occur in analysis.

How to filter viscous samples more efficiently?

You can use a syringe filter with a pre-filter laminate made up of microfibers that trap larger particles before they reach the filter with a designated pore size. This enables lengthy sample volumes to be processed more efficiently.

It is also important to choose a filter with the correct chemical compatibility. For example, using hydrophobic materials with aqueous samples can cause backpressure to build up. Choosing the wrong membrane can lead to other performance issues.

Apply even, moderate pressure to the syringe to ensure a consistent sample is produced. If the back pressure starts to create significant resistance, check to see if there is a problem with your filter.

If you experience increased filtration backpressure, membrane plugging, or reduced column performance due to unfiltered particles entering the injector, consider using a prefilter stack. The degradation of chromatographic column performance is a problem that requires special attention, and routine maintenance also requires careful attention. Adding a guard column in front of the column is equivalent to adding an extra section of packing in front of the chromatographic column, which protects the entire chromatographic column. If you are concerned that adding a chromatographic guard column may cause an increase in dead volume, you can use Hengpu Biotech’s direct-coupled guard column sleeve, which can be directly connected to the inlet of the chromatographic column. The hand-tight direct connection does not require other connecting pipes and can also achieve excellent results. Excellent chromatographic performance without increasing dead volume.

If there is strong resistance when using the syringe, do not force the sample through. Doing so may cause unnecessary problems and may even cause the filter to leak.

Don't automatically select a narrow diameter filter when you have a large number of samples. Please choose a diameter suitable for the volume.