Liquid Phase Always Fails, Don’t Ignore These Little Details

liquid phase in the laboratory,

There are always various problems.

It’s leaking today.

The pressure is high tomorrow.

Delay the progress of the experiment…

Are you helpless?

Is it very melancholy?

Are you worried?

What is causing these problems?

Leakage and blockage are the most common faults in the liquid phase. Generally, the reason for these problems is that the filtration is not done well. Particulate matter causes severe wear on seal components to the point of leaking fluid or plugging the system causing high pressure.

What filter components are involved when we use a liquid phase system? Let’s take a look together.

Solvent Filtration

1.Filter membrane

The mobile phases we use need to be freshly prepared and filtered and degassed before they can be used on the machine. So what problems should we pay attention to when filtering membranes?

I always hear some customers say: “Huh? How did the filter membrane you bought dissolve when filtering the mobile phase?”

Did you choose the right material?

There are many kinds of filter membrane materials, and the compatibility with different solvents is also different. Therefore, special attention should be paid to the selection, purchase and use of filter membranes. Is the mobile phase we use compatible with the filter membrane material?

2.Solvent filter

After we filter the mobile phase and degas it ultrasonically, we start the machine, and then we put the suction filter into the solvent bottle. The materials and shapes of mobile phase solvent suction filters are various, such as glass sand cores, filters, filter heads and so on. They have their own advantages and disadvantages. The glass sand core cannot be ultrasonicated, and it is easy to be broken when changing the mobile phase bottle, while the other filters and filter heads are relatively durable. If they are dirty, you can use acid bubbles or ultrasonics. deal with. You don’t have to be nervous when using it.

3.Flow filter

Some brands of liquid phase will be equipped with a flow filter on the pump, which can filter the mobile phase again, effectively removing mechanical impurities from the system due to wear and tear.

Sample Filtration

1.Syringe filter

Removing intolerant particles from the sample by filtration prior to sample analysis will significantly extend the life of the column. Before column chromatography, syringe filter filtration was the easiest and fastest method for filtration of small volume solutions.

2.Guard column, online filter, impurity trapping cartridge

After the sample is filtered once through the syringe filter, it enters the liquid phase system through the injector. Some samples are dirty and cost-intensive. In order to prolong the service life of the chromatographic column, a guard column or an online filter can be installed before the chromatographic column. In order to achieve the purpose of protecting the analytical column.

In the liquid chromatography separation process, especially in the gradient elution process, it is easy to generate inexplicable chromatographic peaks. There are many sources of ghost peaks, mainly from the mobile phase and pipeline, such as: pollutants in the organic phase, pollutants in the aqueous phase , buffer salts, mobile phase bottles and mixing process generation and more.

Adding a trapping column to solve the ghost peak problem can not only remove impurities in the mobile phase, but also effectively trap impurities in the pipeline and mixer. The installation position of the impurity trapping column is different from the guard column and the online filter. The difference is that it is installed after the mixer and before the injection port.

After the mobile phase and sample are filtered layer by layer, they reach the detector smoothly. After the graph is drawn, the data can be processed.

If the experiment is to be done well, the maintenance of the instrument is indispensable. After using the buffer salt, the system should be flushed in time, the plunger rod and the sealing ring should be cleaned and maintained in time, and the consumable materials should be replaced regularly. Periodic inspections and performance verifications are performed to ensure good instrument performance. As the saying goes, if a worker wants to do a good job, he must first sharpen his tool. Good experimental results are made by excellent instruments, so you must maintain the instruments well.