Quantification keeps increasing throughout the run.. HELP

[mnrevoy]

At the start of every run, we run a 5 point calibration curve and a single control. Throughout the course of the run, we run additional injections of the control as a system suitability check. We have noticed however, that this check keeps failing. It seems that the additional injections of the control (sample prep, different vial, insert and cap), quantify much higher. Around 20% higher. This has us concerned that the unknown results are no longer accurate. Can anyone give me some ideas as to why this is happening.. The system pressure seems stable and there does not seem to be any carryover peaks.. I am at a loss..

HELP!

[tkubowicz]

Hello

First of all...
You described situation that is not very rare. And now you expect us to help you with your problem. Please read again your post and try to find any "starting point" for people here...There is nothing
So...could you please give details about:
-method (parameters, column type, solvents, injection mode/type)
-sample type (solvent, compound)
-quantitation method (ISTD/ESTD, curve type etc)

Regards

Tomasz Kubowicz

[danko]

If the recovery rises up to 20% and satays there it must be a saturation occurrence you’re dealing with.
In order to examine this notion, you’ll need to inject 5 – 6 times the same solution, same volume and register the aria of the peak of interest. If it increases underway for each injection and potentially reaches a level and stays there, this is your issue.

Best Regards

[mnrevoy]

If the recovery rises up to 20% and satays there it must be a saturation occurrence you’re dealing with.
In order to examine this notion, you’ll need to inject 5 – 6 times the same solution, same volume and register the aria of the peak of interest. If it increases underway for each injection and potentially reaches a level and stays there, this is your issue.

Best Regards

Hi danko,
Thank for you for reply. I am not sure what you mean by saturation occurrence. I believe this is our issue however, but don't know how to solve it.