Only for QCs; encouraged ≠ required [Bioanalytics]

posted by dshah  – India/United Kingdom, 2020-08-03 11:17 (1383 d 22:15 ago) – Posting: # 21818
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Hi Helmut!
As per standard SOP - "If the response of internal standard in a sample varies by more than 60% for the isotopically labeled internal standard from the mean ISTD response of CC and QC samples of a particular entire run, then repeat the analysis of the sample under reason Significant variations in response of internal standard"
However - there is no guideline which specifies the limit for variation for IS. Thus, it could be 30/40/50/60 - as per CRO's SOP/requirement/Experience.
The interesting thing could be - whether the QC's analyte/IS standard response are within acceptable range - i.e. whether the QC's were acceptable? if the IS standards response are high, there is possibilities that the QC will be on lower side. I am wondering what other things can be directly correlated and what can be the reason for CRO's acceptability of variation in IS response?

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