Back to the Top
The following message was posted to: PharmPK
There are several ways of determining LOQ refer to the ICH guidelines
(international committee of harmonisation) and it is available on the
world wide web.
However the easiest way to do it is to handle it practically
Work with 5-20 %RSD of your maximum concentration . simply you keep
on diluting the samples with the mobile phase till the peaks are no
longer observed. The smallest peak you get is your limit of
quantification(NB you must be able to quantify it). LOD you can see
the peak but you cannot quantify it.
For instance if my concentration range of calibration curve is from
20-120microgram per ml .Then I can comfortably start diliuting from
instance from 10 to 5 to 2.5 etc till I reach my LOQ and LOD. Then
again as proof inject this concentration into the HPLC to confirm
whether it is indeed the LOQ see with your eyes.
Read the USP and ICH guidelines .
PharmPK Discussion List Archive Index page
Copyright 1995-2010 David W. A. Bourne (email@example.com)