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Dear Members,
This is to seek the group’s opinion on the requirement to intersperse the QC samples in-between the
study samples during sample processing (NOT analysis) when 96 format is employed.
Below are the guideline stated recommendations:
EMEA: All samples (calibration standards, QC samples, and study samples) should be processed and
extracted as one single batch of samples in the order in which they intend to be submitted or
analysed.
US FDA: QCs should be interspersed with study samples during processing and analysis.
As per my understanding, the QCs need to be interspersed so that the variations that might occur
during sample processing steps such as centrifugation, evaporation, etc take place in multiple
steps due to limitation/capacity of the instruments. In contrast, when the samples are processed in
a 96 format, all the samples (within a batch size of ≤ 96 samples) undergo centrifugation,
evaporation, etc at the same time thereby nullifying any sample processing errors.
Appreciate comments from experts.
Thanking you
Venkat
Nektar Therapeutics
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Dear venkat
Thinking logically; Qcs are known concentration samples and study samples are unknown.
Processing or interspersing Qcs with unknown will help to control processing error due to
simulation of processing conditions and hence minimises frequency of failure investigations.
Regards
Shital P.
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96 well plate format is for processing. In an ELISA, the QC are not routinely interspersed; they
could be especially where the reader has only one light tube and the plates is read "as the ox
plows". Other readers have mulitple tubes and the plates is read in a minute or under. LC-MS
samples may be processed by plate but injected in series. The sequence for injection is routinely
where the QCs are the 10th sample, 20th sample etc, throughout the run. I have also seen the
situation where the cals are also scattered. Routinely though, the cals are sequential and the QC
are interspersed at the 10th etc injection.
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Hi Edward,
Thanks for your comments and the explanation. I am not sure, whether I could completely understand
you. May I request you to kindly clarify, in a simple sentence, whether while doing sample
preparation in a 96 well format plate (not analysis), what's the current industry practice? Does it
require to intersperse QC samples in-between study samples when a 96 plate is being used? Appreciate
your comment on the regulatory requirement as well.
Regards
Neel K Mohan
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In a simple sentence describe the processing? Is it serial, parallel, or simultaneous? For plate
based assays using processing such as dilution the processing can be all three. For filtration it
is parallel. For either technique the best procedure woul be to randomly distribute QCs among
samples in processing. This is obviously more critical for serial where samples are processed
individually. It is less so for parallel, and is least important where all 96 wells are processed
simultaneously.
In analysis the distribution can be changed by arrangement of the sequence in LC.
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Dear Neel Kamal,
For small molecular bioanalysis we can distribute QCs randomly in 96 plates however, for ligand
binding assays like for large molecule bioanalysis mostly people prefers group QC with bracketing
concept.
I hope this helps!
Regards,
Sudipta Basu
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