My experience is that very high concentrations (not high amount due to high injection volume!) may shift the peak maximum towards shorter retention times. I think this happens because the amount of substance within the usual peak width exceeds the capacity of the stationary phase, so that the peak broadens forward until the concentration of the the substance in the mobile phase matches the capacity of the stationary phase. If so, the peak end time should be less affected than the peak start time.
When injecting more volume of the same sample solution, retention time may shift forward, when the eluting strength of the sample solvent exceeds that of the initial eluent composition. Peaks often (not always) become assymmetric by fronting in that case and may even be splitted with wart of the substance eluting with the dead volume
The shift of retention time usually based on interaction between compounds with s.p and m.p. On the other hand, the stability of pump pressure also affect the retention time. I recommend you to perform system suitability for evaluate the separation system that you used.
What I am experiencing is exactly opposite. The peaks are shifting towards left but appears on the same wavelength. as we are using Acidic mobile phase it may be damaging to column that why it is happening according to our level of understanding. What do you say about that ?
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