The washing of liquid chromatograph is the guarantee of norm

The third key to the excellent operation of HPLC system by HPLC is to keep the system clean. You need to pay attention to all the places where activities flow through the system, and the frequent local scour will keep your system in a "ready" state.
1. Mobile phase reservoir
First of all, the mobile phase reservoir should be cleaned frequently, or the mobile phase should be replaced once every batch of new samples are made. A dirty reservoir will contaminate the injected active phase. It is suggested that the buffer solution in the storage bottle should not be used for more than one week, while the organic solvent should not be used for more than one month. It is also advocated that the liquid storage bottle should be filled with solvent until the new solvent is replaced (the active phase composition changes), and the old solvent should be poured out to replace the new solvent, which is better than using up the solvent. But this seems to be a bit of a waste for laboratories with a small amount of analytical samples. The engineers of the instrument company advocate that the water in the storage bottle should be changed every day, and the bottle should be cleaned with isopropanol once a week. In some laboratories, 0.1-1 mm formic acid was added to water to inhibit the growth of microorganisms. These practices seem cumbersome, but they can play a role of "sharpening the knife without mistaking firewood cutting".
The washing of liquid chromatograph is the guarantee of normal operation
2. Pump
The next thing to flush is the pump. Do not stop the pump a few minutes after the analysis, especially when the active phase contains a buffer solution (such as phosphate) that is difficult to evaporate. If the instrument is not used continuously, when the active phase evaporates, the hard to evaporate material will stick to the surface of the piston gasket, and the hard to evaporate substance will form a solid accumulation. This is one of the main reasons for pump gasket wear and check valve leakage. Therefore, no matter how long or short the pump is used, the pump must be flushed with non buffer active phase for more than half an hour before the pump is stopped. If there is a buffer salt difficult to evaporate in the active phase, the flushing time should be longer.
3. Automatic injector
The automatic injector should also be cleaned according to the rules. Most of the current instruments are equipped with flushing solution bottle of automatic sampler. Generally, it is only necessary to replace and make up the flushing liquid in time. Use the same method of washing liquid as the washing liquid and the washing liquid should be used in the same way as the washing liquid. At present, the setting and operation of the automatic injector are very simple. If it is allowed at any time (especially at night), it is also a good practice to set up 1 or 2 needles of pure solvent (such as methanol and acetonitrile) after each analysis.
4. Chromatographic column
The pollution of chromatographic column increases with the time of application. The general performance is: the baseline noise increases and the pump pressure increases in the recorded chromatograms when running on the baseline. A useful way to solve this problem is to wash the column (e.g., methanol, acetonitrile and water) with a large amount of active phase after the analysis of each batch of samples or when the column is ready to be removed. The effect of gradient scouring is better, and the specific proportion depends on the specification and properties of the column.
5. Detector
If it is in normal use, the detector will be washed according to its nature and in accordance with the instructions. For example, the UV / Vis detector or FL detector will also clean the pollutants in the flow cell of the detector when the column and system are washed. However, the electroluminescence detector or mass spectrometer needs to be cleaned regularly according to the instructions. When these detectors are used, there will be accumulation of pollutants that are difficult to evaporate, such as the injector, capillary, conical orifice plate, pre quadrupole and other components of the ion source of mass spectrometer, so they need to be cleaned regularly. In addition, when the system connected with these detectors is washed out, Zui can be disconnected from these detectors to reduce the pollution to the detectors.
In a word, if the liquid chromatograph used in the laboratory can do these three tasks carefully, namely degassing, filtering and flushing, your instrument can get excellent preventive maintenance, and it will be more convenient to use. Of course, the problems encountered in practical operation are not so simple, but these three outstanding habits will be the basis for correct operation and application of HPLC system.
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