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Dear Pharm PK Group,
I am developing a method for a compound, structure is not know to me.
I found APCI the best using Agilent LC-MSD.
Conditions: Vcap 2500 , Negative
Coron current 4.0
Drying gas temp 350
Vaporizer temp 425
Nebulizer pressure 60 psi
Drying gas flow 4l/min
Mobile phase ACN/Water
Anybody have an idea of a commercially available compound which
ionizes at the conditions above mentioned, to have as an internal
standard. We do contract work for other companies where they dont
reveal structures.
Thanks in advance for any imput.
Lourdes
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Hi Lourdes,
It must be very challenging working on lc/ms without knowing the
structure of your compound!
Obviously you are happy with the signal you achieve with APCI? I hope
you know the true mw of the analyte are not just seeing adducts etc.
Have you tried ESI?, if you have a better response with APCI your
analyte maybe more non polar than polar.
A common compound used under these lc conditions assuming C18 RP
(although mostly ESI) as an internal standard would be Naproxex (-ve
ion mode) or you could try Naltrexone.
Are you running ACN/water gradient or isocratic? What column are you
using?
Surely if you conduct contract work for commercial sponsors you are
obliged to sign 2 way confidentiality, and hence be exposed to
crucial structural data?
I hope I have helped
Simon
*********************************************
Simon Clark M.Sc.
DMPK Specialist
Analytical Pharmacology,
Antisoma Research Laboratories,
St Georges Hospital Medical School,
Cranmer Terrace,
London SW17 0QS.
simon.clark.-a-.antisoma.com
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The following message was posted to: PharmPK
Hi,
People won't choise an internal standard based on the
MS parameters of the analyte. You should collect as
much as info you can regarding the structure of your
analyte. If you can't, as least it is better to know
the function groups of the analyte, such as COOH, or
SO3H, etc.
Hope this can help.
Xiaodong
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Hi Simon,
Thanks for your useful info, yes I run a gradient with ACN/water on
C18 column, compound is fairly non polar and that is why I selected
APCI which works better than ESI. Compound elutes around at roughly
85-90% ACN.
Regards
Lourdes
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