How long will filters last?
This is one of the most frequently asked questions regarding the use of filters. Unfortunately, there is no standard filter lifetime. You may go for months with very clean samples and mobile phase and not have to change your filters, or they may only make it a few days. It all depends on how clean your fluids are and on the condition of the seals used in your system.
A good lab practice tip is to make the replacement of your filters or frits part of your system’s preventative maintenance routine, which typically occurs every six months. There will also be times when you will need to change your filter or frit in addition to the regularly scheduled changes. But how do you know when it’s time to change them? Here are some hints that may help:
If you notice your chromatogram peaks coming out later than normal, it may indicate that your pump isn’t dispensing the right volume.
If everything on the pump appears to be functioning properly, and if there is no evidence of a leak, then the solvent inlet filter may be clogged, restricting the solvent flow to the pump.
To test this quickly, temporarily remove the solvent inlet filter from the inlet tube and re-run a few standard samples. If the analysis results return to normal, then it’s likely that the pump was not getting enough fluid with the filter in place. Replace the filter with a new one, and begin your analyses again. Do not operate for long periods without a solvent inlet filter, as damage to your system may occur. A useful rule of thumb can be: “if in doubt, throw it out”. Solvent filters are generally inexpensive, making it easier to be safe rather than sorry!
If you notice the system pressure increasing, that’s a good indicator that the frit inside either your inline filter or your pre-column filter may need to be changed.
As your inline filter and pre-column filter do their jobs, the frits inside will collect particles from the fluid pathway. As more particles are collected, less room is available for fluid to move through. Eventually, the pump has to “push harder” to get the same amount of fluid through, causing the system pressure to increase.
To best determine if an inline filter needs maintenance, start at the end of your system and, moving backwards toward the pump, disconnect the fluid pathway fittings one-by-one, monitoring the system pressure. Watch to see if the pressure drops suddenly; if it does, look for the restriction to be in the portion of the flow path last removed from the fluid pathway. If this happens just before a filter, replace the frit inside the filter housing. Remember to be careful and not create a chemical spill when performing this test.
Learn more about the assortment of different type of filters and frits at the product pages linked below, or contact Biotech Fluidics to discuss your filtration requirements.
