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By Anonymous on Sunday, May 30, 2004 - 06:31 pm:
Does anyone have problem with PVP? It always be eluted on the same time with my peak of interest and never let it go with different composition of mobile phase.
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By Chris Pohl on Wednesday, June 2, 2004 - 01:26 pm:
What is your analyte of interest? How do you know PVP is coeluting with it? PVP forms strong complexes with certain compound classes such as, for example, tannic acid as well as a variety of other compounds such as iodine. If your analyte is forming a complex with PVP, try adjusting your sample pH to break out any PVP associated complexes. Elevated pH should decrease PVP association with phenolics.
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By Anonymous on Thursday, June 3, 2004 - 05:37 pm:
It was celecoxib. I found PVP's peak at the same time with celecoxib when I injected the placebo. First time I thought it was carry-over but when I tried it several times I am sure that it wasn't. I have tried to adjust composition of mobile phase but still have no good result.
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By Chris Pohl on Friday, June 4, 2004 - 11:21 am:
I would try adjusting the sample pH. I think if you can ionize the sulfonamide group you should be able to break up the complex. You may need a pH as high as 10 in order to do this, though. If this proves successful you'll need to use a high pH tolerant reversed phase column for your application.
Does anyone have problem with PVP? It always be eluted on the same time with my peak of interest and never let it go with different composition of mobile phase.
(
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By Chris Pohl on Wednesday, June 2, 2004 - 01:26 pm:
What is your analyte of interest? How do you know PVP is coeluting with it? PVP forms strong complexes with certain compound classes such as, for example, tannic acid as well as a variety of other compounds such as iodine. If your analyte is forming a complex with PVP, try adjusting your sample pH to break out any PVP associated complexes. Elevated pH should decrease PVP association with phenolics.
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By Anonymous on Thursday, June 3, 2004 - 05:37 pm:
It was celecoxib. I found PVP's peak at the same time with celecoxib when I injected the placebo. First time I thought it was carry-over but when I tried it several times I am sure that it wasn't. I have tried to adjust composition of mobile phase but still have no good result.
-------------------------------------------------------------------------------------------------------
By Chris Pohl on Friday, June 4, 2004 - 11:21 am:
I would try adjusting the sample pH. I think if you can ionize the sulfonamide group you should be able to break up the complex. You may need a pH as high as 10 in order to do this, though. If this proves successful you'll need to use a high pH tolerant reversed phase column for your application.
