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The following message was posted to: PharmPK
Hi,
I am working on pharmacokinetic analysis of ofloxacin. For extraction
and
precipitation, I used zinc sulphate and sodium hydroxide. I used to
get a
nice curve from this method few weeks back. But now this peak has
dissapeared and instead of this a sharp peak of extaction solvents
appeared. I have also tried methanol (3 parts)for extraction and
precipitation. But with this method also result was not satisfactory.
The
peak I got with methanol was the same as that when I injected plasma
blank. The retention time of ofloxacin is coming at the same time as
that
of methanol and also that of plasma.
I tried different PH of mobile phase also have changed composition.
Now I
am using phosphate buffer and methanol (30:70).
Pls suggest what can be done now.
Rajani
--
Rajani Shakya
Assistant Professor
Department of Pharmacy
Kathmandu University
Dhulikhel, Kavre, NEPAL.
GPO Box 6250, Kathmandu, NEPAL.
Email: rajani.-at-.ku.edu.np
Homepage:http://www.ku.edu.np/pharmacy
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The following message was posted to: PharmPK
A very silly question, but did you inject the zinc-sodium hydroxide into
your system? That may have wrecked your column, stripping it of the
reversed phase, leading to loss of all retention...
Try to check the retention of your column by using it for another,
established assay/compound, and see if it works as you expect. If not,
your column is busted, if so, it is something else.
Good luck, Jan
--
Jan Hendrik Beumer
Pharm.D., Ph.D.
Assistant Professor Pharmaceutical Sciences
School of Pharmacy
The Hillman Cancer Center
Research Pavilion, Suite G.27d
5117 Centre Avenue
Pittsburgh, PA 15213-1863
Email: beumerjh.-a-.upmc.edu
[I worried about the NaOH too - db]
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