Rinse of HPLC
The third point that makes HPLC systems work well is to keep the system clean.
You need to focus on all the places where the flow is flowing through the system, and the constant flushing of these places will keep your system in “Ready” mode.
1. Liquid storage bottle
First of all, you should clean the liquid storage bottle regularly, or change the flow phase with each batch of new samples.
A dirty liquid storage bottle will contaminate the injected flow phase.
It is recommended that the buffer solution should not be used for more than one week, and the organic solvent should not be used for more than one month.
Also keep it is suggested that the liquid storage bottle filled with solvent, change until the liquid storage bottle analysis method need to change the new solvent (mobile phase composition change), replaced the old solvent out new solvent, it is better than solvent will be used up.
But it seems a little wasteful for a lab whose sample size is small.
The engineer of the instrument company suggested that water bottle should be changed every day, and the bottle should be cleaned once every week with isopropyl alcohol.
Some laboratories add 0.1 to 1 mM of the acid to inhibit the growth of microorganisms.
These may seem a little tedious, but they serve as a “sharpener”.
The next thing to flush is the pump.
Never stop the pump after a few minutes of analysis, especially when the liquid contains a hard buffer (such as phosphate).
If the instrument is not continuously used, when the flow phase evaporates, the difficult volatiles will stick to the surface of the piston gasket, and the difficult volatiles will form a solid deposit.
This is one of the main reasons for the leakage of pump seal pad and one-way valve.
So, no matter use must use the buffer before stop pump mobile phase flushing pump in more than half an hour if flow phase is hard to volatilize buffer salt flushing time is recommended should be longer.
3. Automatic sampler
Automatic samplers should also be cleaned according to regulations.
Now, the instrument is equipped with the automatic injection liquid bottle, usually as long as the attention is changed, replenishing the rinse solution.
The washing liquid used in the automatic samplers shall be treated in the same manner as the flow and shall clean the storage bottle or replace the cleaning solution according to the validity and regulation of the solvent.
Now the automatic sampler set, the operation is very simple, if time permits (especially using run at night), after each analysis set into 1, 2, needle pure solvents such as methanol, acetonitrile, is also a good idea.
4. Chromatographic column
The pollution of the pillars increases with time.
Generally, the baseline noise increases in the recorded chromatogram as the baseline is run, and the pump pressure increases.
The most effective way to solve this problem is to flush the pillars (for example, methanol, acetonitrile, and water) with a large amount of fluid when preparing to unload the column after each batch of sample analysis.
It is better to flush the effect with gradient, depending on the description and nature of the column.
If it is normally used, the detector will be washed according to its nature and according to the specification.
For example, the UV/VIS detector or FL detector, in the process of flushing the column and the system, clean the contaminants in the flowing pool of the detector.
However, the evaporative photodetector or mass spectrometer shall be cleaned regularly according to the instruction manual.
These detectors will have the difficult to volatilize the pollutant deposition, such as the injection needle, capillary tube, conical orifice plate and pre-quadrupole etc., which need to be cleaned regularly.
It is best to disconnect the detectors when the system is flushed with these detectors to reduce pollution to the detector.
In a word, if lab daily use liquid chromatograph can seriously do a good job – these three degassing, filtering and washing, your instrument can get good preventive maintenance, users will feel more comfortable.
Of course, the problems encountered in actual operation are not so simple, but these three good habits will be the basis of the correct operation and use of HPLC system.