Routine maintenance of liquid chromatograph
Liquid chromatographs are divided into liquid-liquid chromatography (LLC) and liquid-solid chromatography (LSC) according to whether the stationary phase is liquid or solid. Modern liquid chromatograph is composed of high-pressure infusion pump, sampling system, temperature control system, chromatography column, detector, signal recording system and so on. Compared with the classic liquid column chromatography device, it has the characteristics of high efficiency, fast and sensitive.
Liquid chromatography maintenance:
Be very careful when using liquid chromatograph
When using ferrules, the ferrules at both ends should always be connected to the column core. Regardless of whether you are equilibrating the column or cleaning, you must not remove the ferrule at any time, otherwise it will cause the loss of packing.
Notes on the use of liquid chromatography columns:
Installation of card sleeve column (plus pre-column):
1. Put the card holder into the column core
2. Insert the two jacket pieces into the groove of the column core so that the jacket is higher than the column core (see the figure below)
3. Push up the card holder that has been put on the column core until it is higher than the jacket piece
4. Put the "bullet head" pre-column into the ferrule
5. Screw the ferrule cap and ferrule holder together, then tighten by hand
6. Then connect the other end of the column in the same order
Balance column:
The reversed-phase chromatography column is stored in acetonitrile / water after being factory tested. Make sure that the mobile phase you use is compatible with acetonitrile / water. Because the column may dry out during storage or transportation, you should use 10-20 column volumes of methanol or acetonitrile to equilibrate the column before analyzing the sample; Attention should be paid to "transition" with pure water.
Silica gel columns or polar chromatography columns are stored in n-heptane after factory testing. If the column requires an aqueous mobile phase, equilibrate with ethanol or isopropanol before using the mobile phase
How to balance the column?
During the equilibration process, slowly increase the flow rate to equilibrate the column with the mobile phase until a stable baseline is obtained (if the degree of buffer salt or ion pair reagent is low, it takes a long time to equilibrate)
Column regeneration:
When regenerating the chromatographic column, a modest pump should be used. We recommend not using the pump on your HPLC.
note:
When regenerating the NH2 modified column, because NH2 may exist in the form of ammonium ions, it should be washed with 0.1M ammonia water after washing, and then washed with water until the alkaline solution completely flows out. If the simple organic solvent / water treatment cannot completely remove the impurities adsorbed on the surface of the silica gel, it is very effective to rinse with 0.05M dilute sulfuric acid.
Maintenance of liquid chromatography column:
Use pre-column to protect analytical column (silica gel has certain solubility in polar mobile phase / ionic mobile phase)
The pH stability range of most reversed-phase chromatography columns is 2-7.5, try not to exceed the pH range of the column
Avoid dramatic changes in mobile phase composition and polarity
The mobile phase must be degassed and filtered before use
If a polar or ionic buffer solution is used as the mobile phase, the column should be rinsed out after the experiment and stored in large acetonitrile
Increased pressure is a signal that the pre-column needs to be replaced
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