Bioequivalence and Bioavailability Forum

Bad integration: Example [Bioanalytics]

posted by Helmut  – Vienna, Austria, 2010-07-30 22:24 (5805 d 12:20 ago) – Posting: # 5703
Views: 12,980

Dear Sagar,

a picture tells more than a thousand words.

Following my previous post – which was a little bit theoretical – let’s look at an example (not from the last century; I received it a couple of days ago):

This chromatogram shows the low CC standard of a chiral separation of drug X; first peak is the (inactive) d-enantiomer and second the (active) l-enantiomer. IMHO the analyst made a couple of mistakes…

• He set the integration window in such a way that the first enantiomer was not integrated at all. Debatable from a pharmacokinetic point of view (what if a regulator asks you later on to evaluate the other enantiomer as well?) – but also a killer for the integration algo (see below).
  
  
• He relied on automatic integration (black area), which ended too early due to the small shoulder at ≈9 min. If you compare the noise before and after the peaks it’s clear that this shoulder is most likely not an interference, but random noise.
  
  
• Even if the second peak would have been correctly integrated by his method (▬▬), the area would be underestimated.
  
  
• Only if the first peak is also integrated (▬▬), the peak areas would reflect the enantiomeric ratio of 50:50 of the racemate (which was used in calibration).
  
  
• We are currently investigating whether the CRO did not review chromatograms (bad), or had an SOP in place which did not allow manual reintegration (even worse).

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна! 
Helmut Schütz


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Complete thread:

• Manual integration sagark 2010-07-29 02:26 
  • Manual integration Helmut 2010-07-29 15:30
    • Manual integration ElMaestro 2010-07-29 21:07
      • History Helmut 2010-07-30 01:30
    • LSB - evil, terrible and annoying ElMaestro 2010-07-30 23:46
  • Bad integration: ExampleHelmut 2010-07-30 20:24
    • Bad integration: Example sagark 2010-07-31 12:57
      • Bad integration: Example Helmut 2010-08-01 02:09
        • Better integration? Example Helmut 2010-08-12 20:11
          • Better integration? Example ElMaestro 2010-08-12 23:14
            • Better algorithms / more awareness of analysts Helmut 2010-08-13 13:43
  • Manual integration keshav khude 2010-08-13 09:11