Retention time shift on 1290 HPLC in both directions

Hi Standwi 

Is this an isocratic or gradient separation?

Which of the 1290 pumps does your system have (flexible or high performance)?

/Andy

Hi Andy,

It is gradient separation and our pump is 1290 Infinity G4220A series. I am not sure what is difference between flexible and high performance but we are running application at high pressures (around 600 bars) thus I assume our pump is high performance?  (correct me if I am wrong)

Recently I have tried to switch flow path to different position on switching valve from 1-2 position to 1-6 and I don't observe any retention time shift anymore. Thus I believe that pump is maybe not an issue ? but perhaps there could be issue with the valve? weird thing is we observed leak on both switching valves (the one in autosampler and one in column compartment) so it is difficult to isolate the issue.

BR / Standwi

Hi Standwi 

That model of pump is the high performance (binary) pump.

Sounds like your problem has gone away!

/Andy

Hello Standwi 

Just checking if you still require assistance with this.
If yes, the issue could be a combination of leaks and/or blockages from the valves in the autosampler and column compartment.

If you are running Reverse phased with buffers, it may be worthwhile to replace the column with a union and flush the system with warm LC grade water and then with IPA (switch between the different flow paths using the 2 valves). If this does not work and you have spare rotor seals for the 2 valves (will be 2 different parts), you can try changing them and then perform system pressure tests to make sure they are leak tight.

Hello Standwi 

Just checking if you still require assistance with this.
If yes, the issue could be a combination of leaks and/or blockages from the valves in the autosampler and column compartment.

If you are running Reverse phased with buffers, it may be worthwhile to replace the column with a union and flush the system with warm LC grade water and then with IPA (switch between the different flow paths using the 2 valves). If this does not work and you have spare rotor seals for the 2 valves (will be 2 different parts), you can try changing them and then perform system pressure tests to make sure they are leak tight.