Hello, Hello, everyone. Today, we will introduce you to the last key point of routine maintenance of HPLC – Rinsing.
During daily use, we need to pay attention to all places where the mobile phase flows through the system. Generally, it is recommended to wash the liquid storage bottle, pump, autosampler, chromatographic column and detector regularly, which will keep your system in the best state at any time.
01 Liquid storage bottle
First of all, the flow should be reasonably configured according to the consumption. It is recommended that it should be prepared and used now. Secondly, the mobile phase liquid storage bottle should be cleaned frequently. It is best to replace the mobile phase and flush the liquid storage bottle once.
We can also divide it into several different washing methods.
General cleaning: Wash directly with purified water. It is applicable to the storage of pure methanol and pure acetonitrile.
Normal cleaning: Add an appropriate amount of detergent and brush with a brush; Then rinse with purified water.
Clean standard: the water does not flow down in a stream and does not hang on the wall. Suitable for storage bottles containing mobile phases such as buffer salts or inorganic acids.
Key cleaning: Wet with dilute nitric acid or chromic acid lotion first, and then clean with the method under normal cleaning. It is applicable to the cleaning of storage bottles that may be moldy, such as bottles containing a large proportion of inorganic phase in summer, and bottles that have been storing mobile phase for more than 15 days.
In addition to the provisions under normal cleaning, the cleaning standard shall be determined with pH test paper to make it neutral (pH value of purified water). Make sure that the water from the last bottle is neutral, otherwise it may cause damage to the liquid chromatograph or chromatographic column.
The next thing to rinse is the pump. Especially when the mobile phase contains non-volatile buffer solution (such as phosphate). If the instrument is not used continuously, when the mobile phase evaporates, the nonvolatile matter will stick to the surface of the piston gasket, and the nonvolatile matter will form solid sediment. This is one of the main reasons for the wear of the pump gasket and the leakage of the check valve.
Therefore, regardless of the length of use, the pump must be flushed with non buffer mobile phase for more than half an hour before stopping the pump. If there is non volatile buffer salt in the mobile phase, it is recommended that the flushing time should be longer.
For pipeline rinsing, if the system uses conventional organic phase reagent as mobile phase, it is recommended to flush the system with high proportion of organic phase for more than 90 minutes after each experiment (90% methanol aqueous solution or 90% acetonitrile aqueous solution).
If the mobile phase contains acid, alkali and salt in the system, it is recommended to disconnect the protective column and chromatographic column first, and flush the pump and injector pipeline with pure water for 30 minutes (flow rate 1.0ml/min). During the flushing process, ensure that the injector is flushed for 15 minutes under load and injection respectively, and then transition should be carried out. First, transition the system with high proportion of aqueous phase (10% methanol aqueous solution, or 50% acetonitrile aqueous solution) for 90 minutes, Then rinse with conventional organic phase reagent as mobile phase system method.
Automatic sampler should also be cleaned according to regulations. Now the instrument is equipped with automatic sampler washing liquid bottle, usually as long as attention to timely replacement, supplement washing liquid.
05 Chromatographic column
Column contamination also increases over time. The usual manifestations are: increased column pressure, abnormal peak shape, decreased column efficiency, abnormal resolution, etc.
The most effective way to prevent this problem: at the end of each batch of sample analysis or when you are ready to remove the column, perform routine maintenance on our chromatographic columns according to the corresponding instructions.
For the washing of the detector, it can be washed according to the nature of the detector and according to the instructions. For example, UV/VIS detectors or FL detectors, when flushing the column and system, also cleans the detector flow cell of contaminants. However, evaporative light detectors or mass spectrometers need to be cleaned regularly according to the instructions. These detectors will store non-volatile contaminants during use, such as the spray needle, capillary, conical orifice plate, pre-quadrupole and other components of the ion source of the mass spectrometer, so they need to be cleaned regularly.
At this point, the daily maintenance points of high performance liquid chromatography will be introduced to you. If you want the liquid chromatograph used in the laboratory to operate normally and efficiently, the above daily maintenance is essential.
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