1. After using the column, clean the column with a solvent which can elute the sample well and does not affect the column, and store it. As the solvent for storage, the solvent contained in the supplied column is optimum. When a buffer solution has been used, remove salts from the inside of the column by flowing distilled water into it.
2. When ion-pair chromatography has been performed, the ion-pair reagent in the column can be removed efficiently by cleaning it with methanol and water at a ratio of 50/50 (v/v) after washing it with water.
3. Do not use a chlorinated solvent for storing.
4. Fit an airtight stopper to the column to prevent the inside of the column drying.
5. If the inside of the column dries, feed the stored solvent at a low flow rate of 0.1 to 0.2 mL/min by HPLC, and, after making sure that the solvent flows out of the column outlet, suspend feeding. After leaving the column for about 5 to 10 minutes, feed the solvent as usual. The column may be reused although its performance is lower than the initial performance.
6. When the column is stored for a long period, feed a liquid into the column every one to two months.
7. To maintain the column performance, avoid cleaning the column frequently or using a large quantity of cleaning liquid as far as possible. The column life is reduced only by feeding a liquid. Frequent change of the kind of solvent will lead to the same result.

The column cleaning method varies depending on the kind of column, mobile phase and sample. Normally, clean the column in accordance with the following procedures. For storing, generally, use the liquid contained in the supplied column.

1. Packing material contamination can be removed by flowing a medium polar solvent, such as THF, chloroform and dichloromethane. However, do not store the column with such a chlorinated solvent contained in it.
2. When storing the column for a long period, replace the liquid in the column with methanol or acetonitrile.
3. After using an inorganic salt buffer as the mobile phase, clean the inside of the column with water, replace the water successively with 0.1% phosphoric acid aqueous solution (as much as the column volume), and store the column with acetonitrile or methanol.

1. Deterioration of silica gel is caused mainly by adsorption of polar substances. If the adsorption capacity is reduced by moisture, the capacity can be restored by the following procedures. The method of cleaning chemically bonded columns varies depending on whether they are used in a normal-phase or reverse-phase system.General methods are shown right. However, when replacing the used mobile phase with a cleaning liquid, pay attention to the miscibility between them.
2. When storing the column for a long period, store the column with the following solvent.
・ Silica gel column: n-hexane
・ Chemically bonded column: Ethanol

1. Deterioration of columns is caused mainly by adsorption of ionic substances (metal ions, halide ions, etc.). Deteriorated columns can be regenerated by the procedures shown right.
2. When storing the column for a long period, clean the column well with water to remove inorganic salts, and replace the water with methanol or acetonitrile 100%.

While the column is being used, the column pressure may rise abnormally. The abnormal rise of pressure may be caused by clogging in the column. The clogging may be solved by feeding a solvent having high eluting power. If it cannot be solved by this method, connect the column in the reverse direction, and feed a liquid. Then, the clogging may be solved. However, the column performance may be degraded by this operation. Use this method as a last resort.

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