Chromatography Forum

Hi there ,

I transfered to an old RP-HPLC system .Previously , i used shimadzu system i had no proplem at all and the peak shap is Gussian .

I use the same method in this old system and the peak show tailing whereas in my previous instrument the column is ok even i have just run the column in the previous system and it is ok .So the column is ok what other things might cause peak tailing and retention time is not precise from injection to injection

my work all depend in measuring at time 0 and them measuring after period of time ( it is important to have stable starting reading to be able to have confident result after time x and the peak taling destroy this )

I am quite disappointed dont know what to do
thanks

Tailing - Bad connections/too much extra-column volume in the old system, as compared to the previous system? What column are you using (dimensions, phase, etc); flow rate; injection volume; system; etc.

Retention time variability - Inadequate re-equilibration time after a run? What are your run parameters, gradient conditions, etc.?

First of all please check in your "old" system the pumps and valves to make sure that you are running the same flow rate and have the same mobile phase composition. Make all connections new and let us know if you have a system with 2 or 3 pumps or 1 pump with magnetic valves for gradient composition. Also check if the volume of your detector flow cell is the same as in your "new" system.

If you have checked that the tubing id is the same as in the "good" system I would guess it is the detector cell (if you are using UV) that is too large. Or you could have specific interactions between the analyte and stainless steel components in the "bad" system.