High performance liquid chromatograph (HPLC) is one of the commonly used testing instruments in analytical laboratories, and its applications are becoming more and more extensive. In the course of using this kind of instrument, various problems will inevitably occur, which will directly affect the accuracy of the measured data and the normal operation of the instrument. Next, the issues related to the use of high-performance liquid chromatograph tubes will be shared from the following aspects.
I. The cleanliness of tubes
High performance liquid chromatography is a very sensitive analysis method. If unclean test tubes are used, the accuracy of the test results will be affected. For example, when methanol is used as a solvent to dissolve the sample, the small test tube used is covered with a rubber stopper. Therefore, there is an interference peak with a fixed retention time during each injection. It is later confirmed that this interference peak is caused by the components dissolved by the methanol soaking the rubber stopper. After changing to a glass test tube, the interference peak is eliminated.
II. The dissolution of plastic tubes
In recent years, disposable plastic test tubes have brought great convenience to testers. However, in the process of use, we must pay attention to the dissolution of organic solvents on test tubes. When using this kind of test tube to extract samples, some organic solvents (such as chloroform) dissolve the tube wall, and these dissolved substances can sometimes generate signals on the detector, thereby interfering with the measurement of the sample. At this time, you can use the same experimental conditions to test first to see if the extraction solution can produce interference signals on the detector when there is no extract. If there are interference signals, we can only switch to glass test tubes resistant to organic solvents.
III. Adsorption of the tested sample on tube wall
This problem should also be paid attention to, otherwise it will also affect the accuracy of the test results. In therapeutic drug monitoring (TDM), some tested drugs, such as amitriptyline, imipramine, etc., are easily adsorbed on the wall of the glass test tube. Therefore, polypropylene tubes should be used in operation. In order to prevent the occurrence of adsorption during extraction, 0.5% hexamethylenediamine hexane solution can be used as the extractant, which can effectively prevent adsorption.