Please Paid Attention to These Things With Mobile Phase

One: The mobile phase needs to be restored to room temperature for use

Use the mobile phase after returning to room temperature. When the temperature of the mobile phase is different from room temperature, the baseline level is difficult to stabilize in the state before the mobile phase returns to room temperature, especially when drift occurs, it is easy to generate bubbles.

When water is mixed with organic solvents, the mixed solution will change greatly, which is usually very different from the situation at room temperature, so please be careful.

Two: Avoid using corrosive mobile phase

The mobile phase contains solvents such as concentrated sulfuric acid, concentrated nitric acid, dichloroacetic acid, dichloromethane, acetone, THF, dimethyl sulfoxide, etc., which will deteriorate the strength of the PEEK resin pipe in the flow path, and the PEEK resin pipe is easy to rupture, causing the solvent to splash.

The mobile phase contains halogen ion solvents, such as KCl, NaCI, NH4CI, etc. It is corrosive to the stainless steel material in the flow path. Avoid using the above solvents as much as possible. When necessary, immediately after the analysis, the entire flow path should be cleaned with distilled water.

There: Measure the pH value after adding organic reagents to the mobile phase

The so-called pH value is called pH value based on water as the solvent system, so the correct way to adjust the pH value of the buffer solution is to carry out in an aqueous solution. If the pH value is measured after the organic solvent is added, it will be different from the pH value measured before the addition.

However, the most important point is to maintain consistent operating habits. If it is customary to measure pH after adding organic solvents, just make sure that it is the same every time. Although this operation is not 100% accurate, at least it is consistent with the previous practice. For a complete study, it may be more important to maintain a consistent operation method than to obtain accurate data by measuring the pH value before adding the organic solvent.

Four: Do not put the mobile phase reagent bottle

The mobile phase is completely used up

If the mobile phase is not adequately prepared, in addition to the risk of running the pump and the column dry, there will be other problems. For example, because the water in the solution will evaporate from the top of the reagent bottle, the composition of the mobile phase at the top of the reagent bottle has changed. If the last part of the reagent in the bottle is used, in fact, they are the top part of the original reagent bottle. When they pass through the column, there may be scum remaining in the column.

Five: Use ultrasound to degas the mobile phase

The ultrasonic method is very effective to ensure that the buffer salt used is completely dissolved, but it is not an effective degassing method, and the solution will quickly heat up during ultrasound, which causes the organic reagents in the mobile phase to evaporate. In order to save time, you can spend 5 minutes to filter the mobile phase through a vacuum filter, which can achieve the two purposes of degassing and filtering in one step.