A list of common faults in liquid chromatography

Many novices will be tormented by all kinds of faults when opening liquid chromatography. Here are some common faults and solutions.
The high performance liquid chromatography system is mainly composed of liquid storage bottle, pump, injector, column, column temperature box, detector and data processing system.
For the whole system, the column, pump and detector are the core components, and also the main parts prone to problems.
As a high-precision instrument, if it is not operated correctly in the process of use, it will easily lead to some problems.
The most common problems are column pressure, drift and abnormal peak type.
Today, I'd like to list a few common fault phenomena with the most possible suggestions, so that you can eliminate the faults one by one, regain confidence, and play with liquid chromatography is not a dream!
Phenomenon 1: the baseline is uneven. After flushing, it is normal, and then the plunger rod leaks liquid. After changing the sealing ring, it is normal. Then, when testing the sample, the pump makes a big noise, and the pump stops running immediately. After lubricating the pump, the noise disappears. After injection, the peak height is extremely low. After several times of testing, no peak appears at last. Why?
Suggestions:
1. Check whether the liquid circuit is normal and ensure that the flow and sealing are correct
2. Do not connect the column into the pure product to see if the detector responds. If not, the detector is out of order
3. Check whether your sample is normal
Phenomenon 2: the liquid chromatography six in injector was blocked recently, and the injection valve of the pump began to leak. Some people said that it was blocked after the injection without using methanol to clean the sample. I want to know whether it is necessary to inject several injections of methanol to clean after each sampling, and what is the cause of the leakage?
Suggestion: in fact, to know whether the six-way valve is blocked, you can clean it with organic phase when the pump is stopped. If it can be cleaned normally, it should not be blocked. If the solvent can not be put in, it should be blocked, or you can see if the leakage is loose.
Phenomenon 3: when a sample is connected into six needles by liquid chromatography, the peak area varies greatly, from high to low. Why?
Suggestions: 1. Sometimes bubbles will appear in the injector. If a sample is continuously injected at this time, the peak area will change from high to low. It will be OK to do more purge injector.
2. Use the standard sample to see if it is the problem of the sample; then check whether the column temperature, flow rate, injector and deuterium lamp have problems.
3. Check whether there are bubbles in the quantitative ring
4. Is there any leakage in the six-way valve, column interface and pipeline from pump to column interface
In fact, in the final analysis, there are two cases, either the reason for the sample or the reason for the instrument. If it is a sample, it is suggested to change other substances for test; if it is due to instrument, it may be the injector, quantitative ring, proportional valve and so on.
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