As the core component of a chromatograph, the usage details of the chromatographic column directly affect the accuracy, reproducibility, and column lifespan of the analysis results. The following is a comprehensive analysis of key usage details:
Installation and initial activation
1. System compatibility check: Before installation, a comprehensive inspection of the airtightness and cleanliness of the instrument's gas or liquid system is required. Gas chromatography should focus on the purity of the carrier gas and ventilation safety; Liquid chromatography requires confirmation of the compatibility between the mobile phase and the solvent stored in the column, and if necessary, a transition solvent can be used for conversion.
2. End treatment: Both ends of the chromatographic column should be cut flat and fitted with suitable sealing gaskets to ensure no burrs and good sealing, avoiding dead volume or leakage. When inserting the injection port and detector, it is necessary to strictly follow the depth requirements to prevent column efficiency loss.
3. Aging and balance: The new column must undergo aging to remove residual impurities. Gas chromatography requires segmented heating to the highest tolerance temperature and monitoring of baseline stability; Liquid chromatography achieves adsorption saturation through multiple complete analysis procedures, especially for large molecule compounds that require extended aging time.
Operating condition control
1. Temperature and pressure management: Avoid severe fluctuations in temperature and pressure to prevent damage to the column bed structure. Attention should also be paid to the upper temperature limit of the silica gel matrix column in liquid chromatography.
2. Use of mobile phase and buffer salt: The mobile phase should match the fixed phase to avoid strong corrosive solvents. When using buffer salt, it is necessary to filter it thoroughly and rinse it afterwards to prevent crystallization from blocking the packing material. The solvent ratio change in reverse phase chromatography should be gradual to prevent the collapse of the bonded phase.
3. Sample pretreatment: All samples need to be filtered or centrifuged to remove particulate matter, and solid-phase extraction and other methods should be prioritized for purifying complex matrices. Adding a protective column before injection can effectively intercept particles and chemical pollutants.
Maintenance and Preservation
1. Regular cleaning and regeneration: After long-term use, strong solvents can be used to rinse and regenerate, but attention should be paid to direction and flow rate control. If there is an increase in column pressure or abnormal peak shape, try trimming the column head filling to restore its performance.
2. Storage strategy: For short-term storage, it is recommended to use the current mobile phase (excluding buffer salts); For long-term storage, pure methanol or acetonitrile can be selected, and special types such as ion exchange columns can be added with antibacterial agents. When storing, it is necessary to seal and label the solvent information to avoid light exposure and drying.
Special scenario handling
1. Buffer salt precipitation remedy: When precipitation occurs, a methanol/water mixed solution can be used for reverse flushing, combined with heating to accelerate dissolution.
2. pH range control: The pH value of the mobile phase should be strictly controlled for silica gel matrix chromatography columns. Under special conditions, hybrid silica gel or pre column protection measures can be used.
The use of chromatographic columns requires rigorous operating procedures and maintenance strategies. From installation to daily analysis, the detailed control of each link will affect the column efficiency and service life.