An example of IS response. Need your helps. [Bioanalytics]

posted by Ohlbe – France, 2020-05-26 16:42 (1426 d 01:05 ago) – Posting: # 21472
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Dear Shuanghe,

❝ However, from pure bioanalytical point of view, in my opinion, there's clearly something wrong here.


❝ If runs like this are deemed acceptable according to SOP and not even trig an investigation, I don't care what the creteria is, the SOP may need to be revised.


❝ At the least, the samples from 2nd half of the run should be repeated. I would repeat the whole run.

I would try and understand what happened first, and look at the whole set of information very closely. Anything else that varied here, such as retention times ?

It doesn't look like a subject-specific phenomenon: the QC samples are affected the same way. By the way, how are the results of the last 6 QC samples ? If even the last ones are passing, you could conclude that whatever is happening does not appear to have a large effect on accuracy. I'd still be concerned, until I understand what's going on. The calibration curve is not repeated at the end of the run, so there is no way to check what's happening at the ULOQ, where you may get linearity issues due to detector saturation or ion suppression of the analyte by the IS.


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