Analysis of common problems in front and tail peaks of liqui

Frontal peak
1. The column temperature is low -- I don't understand
2. Improper use of sample solvent -- when the elution capacity of sample solvent is much stronger than that of mobile phase, the front peak will appear. For example, in reversed phase chromatography, when hexanitrile is used as the sample solvent and the mobile phase has weak elution power, the front peak will appear.
3. Column overload --- overload, the samples not reserved come out one after another before the normal peak time, forming the front peak
4. There are small peaks in front of the big peak --- false front peak, that is, there are no separated small peaks in front of the big peak
5. Dead volume of column
Tailing peak
1. Sieve plate clogging: refers to the filter plate at both ends of the column. If the sieve plate is blocked, the sample will be blocked in the sieve plate and the formation time will be delayed, resulting in the tailing of the peak shape when the sample flows out behind the column.
2. Column collapse refers to the loss of column efficiency due to other reasons, and the material cannot be retained on the stationary phase, so that the substance will not be retained on the stationary phase and will flow out with the mobile phase. However, there is still a little column effect, so the tail is formed, that is, a very wide chromatographic peak with a tail.
3. The stigma is contaminated - 1, 2, 3, that is, the samples do not start at the same running line, but start from the back and arrive at the end later, showing a tailing.
4. Additional column effect -- is it post column diffusion?
5. The pH of mobile phase is wrong -- some samples under a certain pH have dynamic equilibrium between molecular type and ionic type, and the transition from ionic type to molecular type will be delayed. Adjusting pH and inhibiting molecular dissociation can improve tailing.
6. Metals
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