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Dear All,
Recently i developed and validated a method,During the time of method application all my calibration samples were meeting acceptance but Quality control samples were not meeting acceptance all of them were showing an accuracy in the range of 40-50% i checked all the parameters and when i changed the column to same make another brand the problem was solved.
What could be the possible reason for this?
Thanks in Advance
Jacob
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Have you tried other options or directly switch over to column change?
Any poor chromatography you found in QC samples and also in CC samples?
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The following message was posted to: PharmPK
Jacob,
What kind of chromatographic assay was this?
If it was LC-MS(MS) it sounds like it could have been a matrix effect causing ion suppression. If you were using a different batch (subject?) of matrix in your standards to your QCs, and one batch (probably the QCs) was particularly grotty then this could explain the data. When you changed to a different brand of column, the effect may have changed retention time so that it was no longer a problem. I'm not sure why this wouldn't have shown up in your validation though. Perhaps there was something in the study samples that was retained on the column and eluted in subsequent injections. Again, changing the brand of column could have shifted it out of the way.
David
David Neville
Principal Scientist
Bioanalytical Sciences
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Dear Jacob,
I don't know wether my point leads to proper reason for this anonymus observation, but I think that the highest calibration concentration leads to saturation/modification of your stationary phase material or instrument response. I've had such experiences in past and were resolved by modification of the experimental conditions. As mentioned by you same thing was not found on other column of same specification, leads to some inherent problem with that specific column. I hope if you provide more details of your experimental conditions and design, will give better understanding of your problem.
Regards
Kuldeep Sharma
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Dear Jacob,
I don't know wether my point leads to proper reason for this anonymus observation, but I think that the highest calibration concentration leads to saturation/modification of your stationary phase material or instrument response. I've had such experiences in past and were resolved by modification of the experimental conditions. As mentioned by you same thing was not found on other column of same specification, leads to some inherent problem with that specific column. I hope if you provide more details of your experimental conditions and design, will give better understanding of your problem.
Regards
Kuldeep Sharma
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