1. Operate according to the instructions of the instrument manual
When accepting the instrument, it is necessary not only to check whether all the parts are complete, but also to check whether the instrument manual is complete and to keep the information properly. Before operating the instrument independently, be sure to read the instructions carefully and follow the instructions in strict accordance with the procedures. This is a prerequisite for good instrument analysis, and once the instrument has a problem, it is also necessary to negotiate with the manufacturer.
2. Prepare a column test standard
Column performance is the key to ensuring analytical results. For newly purchased columns, first test samples should be used to evaluate their performance. If the test conditions provided by the column manufacturer are used and the results are unsatisfactory, a return or exchange may be required. More importantly, the performance of the column will change during the subsequent use. When there is a problem with the analysis result, the column can be tested with the test standard and the result is compared with the previous test result. This helps to determine whether the problem is Out of the column, in order to take the appropriate measures to troubleshoot.
3. Replace the column seal in time
Leakage of graphite gaskets is one of the most common failures in GC. Never reuse the same gasket on different columns. Even if the same column is removed and reinstalled, it is best to replace it with a new one to ensure higher efficiency. If you install a column and find a leak and then replace the gasket, it will take more time. Even if the old pad can still be used, it should be tightened more than before. If it is not good, the capillary column will be broken.
4. Use carrier gas with the required purity
The carrier gas must be of high purity to avoid interference with analysis and contamination of the column or detector. Be aware that the price of a column is more than 20 times the price of a bottle of high purity nitrogen or hydrogen. If you use ordinary gas as a carrier gas because you want to save money, you may have lost the watermelon and picked up the sesame seeds. The auxiliary gas for the detector is preferably also of high purity grade. Although ordinary gas is available when sensitivity is not high, the cost may be that the detector is contaminated.
5. Regularly change the gas purifier packing
The color-changing silica gel can judge the performance according to the color change, but the purifier that adsorbs organic substances such as molecular sieves is not judged by the naked eye. Therefore, it must be replaced regularly, preferably 3 months. If the silica gel is packed with molecular sieves, the molecular sieve should also be replaced when the silica gel is replaced.
6, using a reliable gas pressure reducer
The new pressure reducer must be leak tested when it is used, and it should be leaked frequently during long-term use. This is a good habit to find the problem. If you don't pay attention to this problem, it will cause waste of gas, but it will lead to safety problems.
7, regular replacement of the injection liner
Inlet gasket leakage is one of the common faults in GC. In addition, the aging degradation of the liner can also cause interference in the analysis. For example, the debris falling into the vaporization chamber may also lead to ghost peaks. How long it takes to change the liner depends on the nature of the sample being analyzed and the analytical conditions. Conventional laboratories typically replace one injection liner per day. In any case, the continuous use of a liner should not exceed one week.
8, timely cleaning the syringe
Keeping the syringe clean can avoid interference with the sample memory effect. Wash the sample when it is replaced. When using the same sample for multiple injections, also clean the syringe with the sample itself. When a syringe is temporarily not in use (such as after work), it must be thoroughly cleaned, otherwise the residual sample may stick the core and cause the syringe to be scrapped. Users who use the autosampler should also be aware of this problem, and it is best to replace and clean the syringe frequently.
9. Regularly inspect and clean the injection liner
After long-term use of the instrument, there will be tar-like substances in the injection liner, which is caused by non-volatile components in the sample. In addition, there will be particulate matter accumulation (separator debris, solid matter in the sample) which will interfere with the normal conduct of the analysis. Therefore, it is necessary to check regularly and clean it in time. Note that filling the liner with some silanized quartz glass wool can increase the vaporization efficiency of the sample and prevent the block debris from entering the column and causing blockage.
10, replacement parts must be carried out one by one
When repairing the instrument, do not replace multiple parts at a time, which will cause a judgment error in the cause of the failure. One piece should be replaced at a time, and another piece should be replaced after testing. This may make it easier to accurately determine the cause of the failure while avoiding unnecessary expenses.
11. Make good use of the instrument and analyze the records and archive them regularly.
This is the history of the instrument and should be recorded on a daily basis, including the operator, analysis of samples and conditions, instrument operating status, and more. Once the instrument has a problem, this is an important resource for finding the cause.