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RegisterDuplicate LLOQ and ULOQ [Bioanalytics]
Dear Helmut,
In my experience, yes. I mean, most people analysing only the first and last samples in duplicate.
Their rationale is only to avoid having to truncate the curve if the first or last samples fail. If there is no objective reason to use the second value, they use the first to avoid nasty discussions with regulators (such as: the run passes with the second injection but fails with the first, why did you choose the second ? Did the first one fail by accident, or did the second one pass by chance ?).
Using both repetitions would make sense to improve the fit (the two ends of the curve are where you have the more uncertainty). But then you get into other discussions such as: if you consider you need duplicate analysis to get a correct fit, then you should also analyse the subject samples in duplicate...
Some other labs analyse the whole curve in duplicate, once at the start of the run and once at the end, to compensate for possible drifts. Personally if there is a drift I would rather shorten the run... But I think that's a discussion we had previously on the forum.
Regards
Ohlbe
❝ ❝ What most people do is that they only use one of the two replicates of the LLOQ and ULOQ samples. Usually the first replicate is used,…
❝
❝ Really most people?
In my experience, yes. I mean, most people analysing only the first and last samples in duplicate.
❝ That’s strange to me. Why the first and not the second? Why not both?
Their rationale is only to avoid having to truncate the curve if the first or last samples fail. If there is no objective reason to use the second value, they use the first to avoid nasty discussions with regulators (such as: the run passes with the second injection but fails with the first, why did you choose the second ? Did the first one fail by accident, or did the second one pass by chance ?).
Using both repetitions would make sense to improve the fit (the two ends of the curve are where you have the more uncertainty). But then you get into other discussions such as: if you consider you need duplicate analysis to get a correct fit, then you should also analyse the subject samples in duplicate...
Some other labs analyse the whole curve in duplicate, once at the start of the run and once at the end, to compensate for possible drifts. Personally if there is a drift I would rather shorten the run... But I think that's a discussion we had previously on the forum.
Regards
Ohlbe
—
Regards
Ohlbe
Regards
Ohlbe
Complete thread:
- Calibration Curve auditor 2012-01-20 11:15
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Duplicate LLOQ and ULOQ Ohlbe 2012-01-20 11:59
- Duplicate LLOQ and ULOQ Helmut 2012-01-20 13:09
- Duplicate LLOQ and ULOQOhlbe 2012-01-20 14:26
- Duplicate LLOQ and ULOQ Helmut 2012-01-20 18:02
- Calibration Curve auditor 2012-01-21 05:45
- Calibration Curve Helmut 2012-01-21 12:35
- Calibration Curve Ohlbe 2012-01-21 13:44
- Calibration Curve Helmut 2012-01-22 21:48
- Calibration Curve auditor 2012-01-21 05:45
- Duplicate LLOQ and ULOQ Helmut 2012-01-20 18:02
- Duplicate LLOQ and ULOQOhlbe 2012-01-20 14:26
- Duplicate LLOQ and ULOQ Helmut 2012-01-20 13:09
- Duplicate LLOQ and ULOQ Ohlbe 2012-01-20 11:59
Ing. Helmut Schütz