Ma. Teresa M.Mercado
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2006-03-31 06:49
(6650 d 10:02 ago)

Posting: # 81
Views: 9,237
 

 peak height [Bioanalytics]

When are peak heights used for quantitation? What are the advantages of peak height over peak area measurements?
Helmut
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Vienna, Austria,
2006-03-31 14:50
(6650 d 02:01 ago)

@ Ma. Teresa M.Mercado
Posting: # 82
Views: 7,352
 

 peak height

Dear Teresa!

❝ When are peak heights used for quantitation?


If (integration of) peak areas is unreliable! ;-)

❝ What are the advantages of peak height over peak area measurements?


OK, let's be serious:
One of the main principles in bioanalytical method validation is '...that the method should be suitable for the intended use'.
We should always keep in mind, that we want to get valid results, and not only fulfil some overstringent requirements.
If we observe interferring peaks in the chromatogram (in some of the subjects of a biostudy, or only at some time points after a meal - in Vienna we call them 'Schnitzel-Peaks'...) it may be better to go for peak-heights, since they are influenced to a lesser extent.
On the other hand, if we observe a decrease in column-performance within a batch and we have a 'clean' chromatogram, we should opt for peak-areas.

My recommendation is to validate both peak-heights and -areas, and depending on your expectations define one of them as the 'standard' in your analytical protocol, and the other one as an 'alternate'. If you experience problems in a praticular batch, you may apply the alternative evaluation and still get valid results.
One important point: you only may go with the alternative method for a complete batch (CC, QCs, unknowns), not for single chromatograms within a batch.

Suggested reader from LC/GC-Europe, Feb. 2006.

Remark: we never got problems with such a procedure during our regulatory GLP/GCP-inspections, but only with some of our overcautious sponsors, which resulted in unnecessary repeated batches and excluded subjects. ;-)

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