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The following message was posted to: PharmPK
hello
can anybody guide me in using the internal std for a pcokinetic assay
using HPLC
regards
amrutesh
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The following message was posted to: PharmPK
Dear Amrutesh,
You should choose closest similar molecule (in terms of physico chemical
properties) to your Drug to be used as internal standard. Closest the
RT of
internal standard and physico chemical properties the better IS it would
be.
Thanks and Regards
M.L.A.Baig
Res. Scientist
Wockhardt Research Centre,
Plot No. D-4, M. I. D. C. Area, Chikalthana,
Aurangabad-431 210 (India)
Email : LBaig.aaa.wockhardtin.com
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[OK, another try with a different mail server ;-) Hopefully this will
get out to everyone but it may still be a temporary solution so please
bear with me as I explore options, thank you - db]
The following message was posted to: PharmPK
Dear Amrutesh,
You very well know that the purpose of IS is to normalise any errors
(sample
processing to injection volume) during the bioanalysis. Now the IS you
choose must ideally elute after the compound under investigation (in
order
to avoid any possible interference with the solvent front and
metabolites).
As long as you are able to declare the structure of the compound you
want to
use as an internal standard, it is ok.
Try running a few standard compound, in a fast mobile phase (Less
buffer and
more organic phase like 20:80) on reverse phase (if you are using
reverse
phase chromatography) and depending on the retention time you may play
with
the mobile phase combination to get a compound most suitable for your
compound under investigation. If you are working with preclinical
molecules
then it would be easy to use previous molecules for which bioanalytical
method is available.
Feel free to contact me if you need further clarification, All the best,
Jagannath
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