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As a costly analytical instrument, gas chromatographs are expected to last longer, so daily maintenance and good usage habits are essential, which also allows the GC instrument to work properly and maintain good detection results. Today, I will give you a summary of 10 small tricks to get the daily maintenance of the gas chromatograph for your reference.
1. Operate according to the procedures of the instrument manual
This is mainly for the newly purchased and installed instruments. It is necessary not only to check whether the parts and spare parts are complete, but also to check whether the instructions are complete. It is necessary to keep these materials in a safe place for future reference. Before operating the instrument independently,gas chromatography headspace vials be sure to read the instruction manual carefully and operate it in strict accordance with the regulations. This is a precursor to instrumental analysis and is easy to communicate with the manufacturer when problems occur with the instrument. Especially for instruments that are still under warranty, if the fault or damage caused by improper operation, the manufacturer will not repair it for free, and sometimes the cost is quite objective.
Second, to ensure the airtightness of the vaporization chamber gasket
1. The life of the silicone rubber pad of the gas chromatograph inlet is related to the temperature of the vaporization chamber. Generally, it can be used dozens of times. When the silicone rubber gasket leaks, it will cause the fluctuation of the baseline, and the reproducibility of the analysis will be worse, thus making The result is not allowed.
2. Due to excessive puncture of the injector, the silicone rubber pad debris enters the vaporization chamber. If there is too much debris, the high temperature will affect the stability of the baseline or form a ghost peak. Therefore, in order to ensure the normal operation of the analysis, please change the gasket frequently and check the airtightness of the vaporization chamber frequently.
Third, the regular leak detection of the gas path
1. Under normal circumstances, leak detection has been carried out when purchasing new instruments, but if the sensitivity is reduced, the retention time is prolonged, and the wavy baseline is found during use, the leak should be re-examined, especially the hydrogen gas path. Frequent leak detection should be done to avoid danger.
2, some control valves use "O"-shaped rubber ring, due to long-term wear, may leak air; the inlet silicone pad is not often replaced, the column is not connected well ... may leak, so it is necessary Always check for leaks!
Fourth, often clean the vaporization chamber or liner gas chromatography headspace vials
1. Due to long-term use, a large amount of high-boiling substances are often collected in the vaporization chamber and the liner of the gas chromatograph. If a high-boiling substance is analyzed for a certain time, the excess peak will be released, which will affect the analysis band. Therefore, the organic solvent is often used. Clean the vaporization chamber and liner.
2. Cleaning of the vaporization chamber: The column is removed. In the case of heating and aeration, anhydrous ethanol or acetone is injected from the inlet, repeated several times, followed by heating and aeration.
5. Cleaning of the thermal conductivity detector (TCD)
1. Remove the column, replace it with an empty short column, pass the carrier gas, raise the temperature of the column oven and the test chamber to 200-250 degrees, and inject 2 ml of organic solvent from the inlet, repeat several times. Vent to dry.
2. The bridge current must not be energized during cleaning, otherwise the detector will be damaged! ! !
Sixth, hydrogen flame detector (FID) cleaning gas chromatography headspace vials
1. The purpose of cleaning is to increase the insulation of the detector.
2. When the pollution is serious, the collector, polarizer and nozzle can be removed. The collecting pole and the polarizing pole can be scrubbed with absolute ethanol. The base and the nozzle are repeatedly washed with organic solvent, and the venting line should be thoroughly cleaned. The nozzle opening should be smooth and smooth. If there is burr, it can be polished with oil stone or assorted mortar and sandpaper. Rinse repeatedly with ethanol and then alternately blow dry with hot cold air.
3. The insulators for fixing these electrodes can be immersed in absolute ethanol for 10-15 minutes, wiped clean with silk or gauze, and installed after use.
4, the assembly should be restored to its original shape, so that the nozzle, polarization pole, and collector set are concentric, and the side view polarization pole and the nozzle mouth are at the same level.
5. Note: After cleaning, all accessories are prohibited from direct contact by hand. Wear clean gloves when installing. All tools should be cleaned and dried before use.
7. Cleaning of Flame Photometric Detector (FPD) and Nitrogen Phosphorus Detector (NPD)gas chromatography headspace vials
Since the above two detectors are basically similar to the FID structure, the cleaning method refers to the cleaning of the FID. NPD focuses on the cleaning of enamel; while FPD should focus on the cleaning of the light window, but be careful not to expose the photocell to strong light.
???Eight, the cleaning of the electron capture detector (ECD)
1. The cleaning method is the same as the thermal conductivity detector (TCD).
2, cleaning organic solvents can not use electronegative organic solvents such as chloroform, carbon tetrachloride, etc., high purity chromatographic grades of benzene, n-hexane and other solvents.
3. For the source of radiation, the temperature of the Ni63 detector is between 250 and 300, and the temperature of the source is not high.gas chromatography vials
4. Personal protection when necessary when cleaning ECD! !
Nine, retain the complete instrument usage record
The instrument usage record is the history of the instrument and should be recorded on a daily basis, including the operator, analysis samples, conditions, instrument working status, etc. Once the instrument has problems, this is an important information for finding the cause. Some research laboratories often pay less attention to the filling of instrument usage records, which is a problem that needs attention.
Ten, replacement parts must be carried out one by one
When servicing a gas chromatography vials instrument, do not replace multiple parts at a time, which is easy to make a judgment error. One part should be replaced at a time, and the other should be replaced after testing. This will allow you to more accurately determine the cause of the failure and avoid unnecessary expenses.
This is the end of the introduction of 10 small tricks to get the daily maintenance of the gas chromatograph. I hope it can help you.