If it is not necessary, the front end of the column entrance can be cut off for half a meter, and then the temperature is programmed to age.
Only when the chromatographic column is really polluted, or the chromatographic column efficiency has decreased, which affects the normal analysis, can it be solved by cleaning.
Specific cleaning methods and requirements: capillary gas chromatography columns must have bonded and crosslinked stationary phases before they can be cleaned with solvents. Cleaning the non-bonded stationary phase with solvent seriously damages the chromatographic column. . The solvent cleaning device will be connected to a pressurized gas source (N2 or helium), and the chromatographic column will be inserted into the cleaning device. Add the solvent into the sample bottle, and then pressurize the solvent bottle with an air source. Pressure forces the solvent to flow through the chromatographic column. The residue will be dissolved in the solvent and washed out of the chromatographic column with the solvent. Then the solvent is removed from the chromatographic column and the chromatographic column is aged appropriately. Before cleaning the chromatographic column, cut it half a meter from the front end of the chromatographic column (that is, the end near the injector). Insert the end of the chromatographic column connected to the detector into the cleaning device. Various solvents are usually used to clean the chromatographic column. The solvent used later must be mutually soluble with the previous solvent. Never use high-boiling solvents, especially not as the last solvent. Solvents for dissolving samples are usually a good choice.
It is recommended to use methanol, dichloromethane and hexane, which are effective in most cases. Acetone can be used instead of dichloromethane to avoid using chlorine-containing solvents, but dichloromethane is one of the best cleaning solvents. If you are injecting water-based samples (such as physiological fluids and tissues), please rinse with water before using methanol. Some residues from aqueous samples can only be dissolved in water, but not in organic solvents. Water and alcohol (such as methanol, ethanol and isopropanol) should be used to clean bonded polyethylene glycol-based stationary phases (such as DB-WAX, DB-WAXetr, DB-FFAP, HP-Innowax), but this method is generally not recommended.