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1. When there is no carrier gas flowing through, the stationary phase in the column decomposes rapidly due to heat. Therefore, the installation and commissioning staff as well as training engineers in Kexiao Instruments’ technical department will definitely emphasize to the operators that the carrier gas must be supplied before heating the column box (furnace) – a requirement similar to that for TCD operation – and the carrier gas can only be turned off after the column box has cooled down. 2. If dust or other particulate matter is present in the carrier gas, it can cause rapid damage to the chromatography column; at the same time, care must be taken to prevent particles or dust from entering the vaporization chamber. Therefore, a purifier is necessary before the carrier gas enters the instrument’s piping system ； 3. Moisture in the carrier gas is adsorbed on the inner surface through the liquid film of the stationary phase, which can replace or disrupt this liquid film. Therefore, the stronger the polarity of the stationary phase, the more necessary it is to use a dry carrier gas. For example, stationary phases such as OV-1, SE-30, SE-54, and OV-101 require little drying of the carrier gas, whereas PEG20M, FFAP, and SP1000 demand a highly dry carrier gas. However, the situation is exactly the opposite for columns coated on a barium carbonate deposition layer: columns coated with polar stationary phases can withstand direct injection of aqueous samples, whereas those coated with non-polar stationary phases cannot. But in any case, it is advisable to dehydrate the carrier gas before it enters the pipeline ； 4. For those fixing agents that can be oxidized (such as PEG-20M, Carbowax, FFAP, etc.), it is also important to remove oxygen from the carrier gas. Since N2 and He contain relatively high levels of O2, while H2 contains less O2, ECD and FID typically use high-purity N2 as the carrier gas, whereas TCD uses H2 as the carrier gas. At the same time, when the system is not in use, the exhaust end should be sealed to prevent oxygen in the air from oxidizing the stationary phase of the chromatography column. The GPI-Ⅱ type three-gas-path gas purifier produced by Kexiao Company was developed specifically for the reasons mentioned above; it can be equipped with different purification agents as needed to carry out filtration, dehydration, and removal of oxygen and organic substances. ” 5. In most cases, the lifespan of a column is inversely proportional to its operating temperature. Using a slightly lower upper temperature limit can significantly increase the column’s lifespan; the shorter the time the column is maintained at a higher temperature, the less impact it has on its lifespan. (See attached table) 6. Solvents such as water, alcohols (especially methanol), and carbon disulfide have a very strong ability to displace the stationary phase; therefore, for the solvent-free injection method and on-column injection method, which are used to intentionally concentrate a considerable amount of solvent on the column (solvent effect), the solvents should be carefully selected based on their adsorption affinity for the column walls (or the likelihood of the stationary phase being displaced). (For example: Methanol is not suitable for PEG20M; propanol often causes degradation of silicon compounds.) 7. The main advantage of capillary columns is their high column efficiency. However, column efficiency reflects not only the quality of the column itself but also the overall efficiency of the entire system used for sampling. In other words, from the moment the sample enters the system until the peak appears, every factor that can affect the peak width or separation performance – such as the sampler, the connection to the column, the location where the auxiliary gas is introduced, the dead volume in the tubing, and problems with the liner inside the sampler – will inevitably impact the column efficiency. 8. A poor-quality column, due to improper installation, can result in a decrease in the theoretical number of theoretical plates, broadening or tailing of the peak shape, adsorption-related tailing or disappearance of the active substance, reduced sensitivity, and poor separation of components. 1) Connection of the injector to the capillary chromatography column: Split injection: The split point should be located in an area where the carrier gas flow rate is high. Direct injection without diversion: It is best for the chromatography column not to extend into the injector, in order to avoid areas that cannot be reached by the airflow; it is usually connected directly to the end of the injector. 2) Connection of the detector to the outlet end of the chromatography column: For the FID, not only should its insertion depth exceed that of the tail gas and H2 gas inlets, but it is also preferable to position the column outlet end 1 mm below the nozzle of the FID; for a micro TCD, it is best to insert it at the gas inlet of the TCD. It can improve mild trailing. Appendix: Operating temperatures for common chromatography column stationary phases 1. Polydimethylsiloxane-based stationary phases: ov-1, se-30 (elastomers); ov-101, sf96, dc2000 fluids). The maximum operating temperature is 300°C, but reducing this limit to 280°C can significantly extend the lifespan of the column. Generally, elastomeric stationary phases are more stable than fluid-based ones. SF96 and DC200 are not suitable for GC/MS analysis due to their high levels of residual catalysts and impurities. 2. Polyphenylethylsilicones: SE-52 (elastomer, 5% phenyl), SE-54 (elastomer, 5% phenyl, 1% vinyl), DC10 (liquid, 35% phenyl), OV-17 (liquid, 50% phenyl); the maximum operating temperature is 250°C. SE-52 and SE-54 exhibit excellent stability at 280, are commonly used in GC/MS analysis, and can handle large sample volumes that exceed normal limits. As the phenyl content increases, stability decreases. 3. Polycyano-propyl silanes are also polar silicon-based stationary phases: ov225 (liquid, 25% cyano-propyl, 25% phenyl), silav10c, sp2340 (liquid, 75% cyano-propyl); the actual upper temperature limit is 250°C. 4. Polyethylene glycol-type (carbowax or Peg) fixing agents are mixtures of ethylene oxide polymers, and their names reflect the average value of the range of their molecular weights. Carbowax 20000 (waxy solid), FFAP (Carbowax 20000 with terephthalic acid at both ends); the actual maximum temperature is 220°C.