Why do HPLC mobile phase solvents need to be filtered and deaerated
To answer this question, let’s first understand what a mobile phase is. Simply put, a mobile phase is a fluid in which a carrier carries a substance into and through the stationary phase. The mobile phase can be either a water-organic mixture of the buffer combined with an organic solvent or an organic-organic mixture.
It is very important to check if the solvent is completely miscible before starting chromatographic analysis with mobile phase solvents. Then pay attention to whether they will react with each other when mixed. If chemical reaction occurs, it will affect the use of mobile phase and the correction of chromatographic analysis.
Some chromatographers may say, can I use HPLC-grade solvents directly?
uHPLCs recommends that even HPLC-grade solvents be filtered before use. Why? It is mainly because that some suspended particles or impurities are micron-sized, they are invisible to the human eye, we can not judge that a clear solvent is “completely clean”. Just like the tap water, it looks clean, doesn’t it? But it actually contains a lot of other insoluble substances. If you do not remove suspended particles and impurities during chromatographic analysis, it will affect the performance of the HPLC system. Not only that, because the column is porous structure, particulates are likely to block the column, increase back pressure, affect the flow rate and even damage the pump.
We all know that liquid chromatography systems operate at very high pressure. If the air contained in the mobile phase is not removed, as the mobile phase passes through the column, the bubbles in it are compressed by pressure, bubbles are released by atmospheric pressure as they flow out of the column and into the detector which will increase the detector noise, make the baseline unstable, and eventually cause that the instrument doesn’t not work normally, especially in gradient elution.
How to minimize the occurrence of such situation? uHPLCs recommends:
It is most important that mobile phase should be filtered by a filter before use. uHPLCs inlet solvant filters can effectively remove the solid particle impurities in mobile phase. Unfiltered solvents or microorganisms growing in solvent bottles can shorten the life of solvent inlet filters and reduce the performance of the pump. So regular cleaning or replacement of inlet solvent filters is required. Inlet solvant filters are made of high quality stainless steel 316L. They are corrosion resistance and suitable for most of solvants. Stepped connection outlets at the top of the filters can be connected with tubing of 1.5mm, 2.2mm and 3.5mm inner diameter respectively. Various styles and models are available for selection.
Fresh preparation of mobile phase before use. It is best to redistribute mobile phase before each analysis and do not allow the mobile phase to be stored overnight or for a long time. This is very easy to nourish microorganisms.
Use a HPLC guard column before the HPLC column to avoid clogging. uHPLCs can hold back those strongly retained and non-adsorbable compounds. The filtration of samples and mobile phase can maintain the HPLC guard column’s adsorption capacity of chemical contaminants, maintain column effectiveness for longer periods of time, protect HPLC column from contaminants, remains stable and leak-free at rated back pressure and high flow rates.