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Dear all,
I was wondering if anybody in the group could kindly give me some
hints to extract a drug and its metabolite from rat feces.
My drug is a carboxylic acid and my detection method is LC-MS.
Thank you in advance.
Marco Lai
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The following message was posted to: PharmPK
Hello Lai
I tried this method couple of years back:
1. To the dry rat feces add minimum amount of water and allow it to
stand for 15 minutes.
2. Add Methanol and allow to stand for 15 min with occasional vortex or
in a flask shaker.
3. Remove methanol by rotary evaporator as much as possible.
4. Use TLC methods to elute the polar and color impurities and extract
the bands you observe.
5. Use appropriate solvents (polar/nonpolar) to extract the various
bands and analyze using LC-MS.
Atul
Venkatesh Atul Bhattaram
Pharmacometrics
US Food and Drug Administration
"The contents of this message are mine personally and do not necessarily
reflect any position of the Government or the Food and Drug
Administration."
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Hello, Marco:
Here is what I adopted for metabolite profiling (cold material) in
rat feces:
1. Add 3 volume of water to feces pallet and homogenize
2. Extract homogenized feces with at least one volume of methanol and
vortex well.
3. Centrifuge and dry down the supernatant for LC/MS analysis.
4. If you have radiolabeled material to start with, extraction
efficiency could be checked and
more than one extraction might be necessary.
Regards,
Jennifer Yang
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Dear Marco,
If your drug is an acid, I used to find sometimes that it helped to
include an acid (formic, acetic) in the extraction solvent, e.g. 1%
or 2% formic or acetic acid in methanol:water 1:1 v/v. Good luck
Clive Till
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The following message was posted to: PharmPK
Hi,
If I remember the start of this link correctly, one is trying to extract
a carboxylic acid drug from feces. In my experience any time you use
methanol for fecal extraction you tend to convert the acid to a methyl
ester, especially under acidic conditions. I would rather use acidified
acetonitrile or preferable plain acetonitrile for extraction as a
starting point.
Sandeep
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Dear lai
The rat feces must be dry if not you need to try it by freeze drier.
I thing you can start with acidification of analyte by using 1 %
acetic acid or 10% diluted H3PO4 or anyother weak acids, then you can
add suitable organic solvents to extract the analyte from the matrix.
I hope this would help you. GoodLuck.
A.Karthik
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