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hello members,
i am facing a difficulty in the extraction of pyrazinamide from
plasma.
my system is api 3000, mobile phase is acn:water:formic acid in ratio
of 10:90:0.3 v/v. I am using LLE with ethyl acetate as extraction
solvent. other drugs that are targeted along with pyrazinamide are
ethambutol and isoniazid. the other two are giving good extraction.
pka of pyrazinamide is 0.5. the recovery of pyrazinamide is the issue.
i have tried acidification of plasma with 25microlitre of 1% Trichloro
acetic acid but recovery of pyrazinamide was not found to be
consistant. kindly pool in some suggestions for the pyrazinamide
extraction or all three in together( all the drugs are of polar ,
basic nature)
thanks and regards,
gagandeep singh
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The following message was posted to: PharmPK
Hi,
If the pka of pyrazinamide is 0.5, then it is not a base.
Xiaodong
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The following message was posted to: PharmPK
Hi,
pyrazinamide is a base and molecular weight is only 123. I would
suggest you using cation exchange SPE for extraction for those very
polar basic compounds.
Xiaodong
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Dear Gagandeep,
Since all the three drugs are basic in nature you must be adding base
to the sample before proceding with LLE. Try using strong base.
Dr. Mandar Mote
Sr. Manager Bio-analytical
Bio-equivalence Division
Macleods Pharmaceuticals Ltd.
Mumbai.
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