Protection column selection and use steps

What should be paid attention to when selecting and replacing the guard column

First, the choice of guard column

The principle of selecting the guard column is to select a shorter guard column structure as much as possible, and to have a relatively small retention chromatographic packing for the separated sample, on the premise of meeting the analytical separation requirements.

The first thing to consider before choosing a guard column is whether the sample is clean. For most analytical work, a 1cm long guard column provides adequate protection. However, if the sample is very unclean, or if the guard column is to be replaced frequently during work, then a 2 cm or 3 cm long guard column should be selected. However, as the guard column is lengthened, the retention time will also become longer.

The inner diameter of the guard column should be the same or equivalent to the inner diameter of the analytical column. The packing method of the guard column is also important. There is currently a guard column for film filling, which is simple and convenient to use and can be dry-packed in the laboratory. However, its biggest drawback is that it is uneconomical, especially for the specific situation in China, and the relative cost of one-time use is relatively high. In addition, the membrane packing method has a limited packing of chromatographic packing and can only provide limited protection; however, because the loaded chromatography is less and the length of the guard column is shorter, the retention time of the sample is analyzed. The impact is also small. Another type of guard column structure is that it shortens the chromatographic analysis and is designed to be directly connected, hand-tight or monolithic. The monolithic design is installed directly on the chromatographic column by the manufacturer of the chromatogram and must be ordered with the chromatographic column and can be used very easily, but cannot be modified. The direct-connected design allows the chromatographer to be installed at any time, can be used with any brand of chromatography column, and can choose a different guard column length depending on the sample. Keep your hands tight. In addition, from the structure of the guard column, it is further divided into whether the pillar of the guard column can be replaced. It can reduce the cost of using the guard column.

In general, the choice of guard column packing is determined by the packing of the analytical column. Normally, the same chromatographic packing as the analytical column can be selected. However, depending on the actual work, it is not necessary to completely match the packing of the analytical column.

Second, when should the guard column be replaced?

The guard column should be replaced when one of the following conditions is met.
a, the theoretical number of columns of the column decreased by more than 15%;
b, the column front pressure rises by more than 15%;
c, the most difficult to separate substances for resolution decreased by more than 15%;
d, the number of sample injections exceeds 150 times;
e. The mobile phase passes through a column volume of 1500 times.

Third, the protection column / protection column replacement steps
1. Disconnect the column from the guard column and replace the guard column (or the core)
2. Replace the guard column (or remove all the tape from the guard core, replace the column core, and connect the guard column)
3. Rinse the replaced guard column with methanol for 30 minutes.
4. Connect the column

Fourth, in-line filter pre-column principle difference between the guard column

The inline filter is between the pump and the injection valve, only the sieve plate, just physical filtration,

The guard column is between the injection valve and the column, and has a packing to adsorb the substance.

Pre-column is a confusing concept, pre-column, which can be literally translated as a pre-mixed column, placed between the pump and the injection valve, with a silica filler to reduce the column packing from being dissolved by the acid and alkali mobile phases.

At the same time, there is also a precolumn as a guard column.

Five, cleaning

The guard column should first be removed from the analytical column during cleaning to prevent the eluent from entering the analytical column; then select the appropriate mobile phase for flushing.

Disclaimer:

We reserve the right to modify the pictures and contents involved in the product introduction. The products, pictures, and company, part names, and numbers mentioned are purely intellectual or technical exchanges. This does not mean that the related products are produced by related companies. manufacture. All company names, images, and trademark technical description texts in this presentation are owned by each holder.