By Renata on Thursday, July 8, 2004 - 05:44 am:

Hello friends,

I'm trying to develop an aplication for ibuprofen, a chiral structure. As I could find in some researches, the therapeutic effects of the enantiomers can differ a lot.

Questions:

1) I'm using USP standard to assay ibuprofen, but it's not specified if it's levo or dex. Will I have to reach a method that separates the two peaks or is it possible to assay only one peak (the two structures together)?

2) If I get an application of two peaks, how will I know which one is levo or dex if I don't have specific standards?

3) The assay of Ibuprofen is given adding the area of the two peaks or do I have to quantify each peak separately?

Sorry for many question but I've never dealed with enantiomers.

Thanks in advance

Renata Amaral

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By Heinz Sarter on Thursday, July 8, 2004 - 06:27 am:

hello renata,
if you are interested, i can deliver the hplc conditions and sample preparation for the determination of both enantiomers in gelatin capsules.
heinz

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By Renata on Thursday, July 8, 2004 - 06:54 am:

Hi, Henz

Please, send me the application by e-mail.

thanks.

Renata Amaral

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By HW Mueller on Thursday, July 8, 2004 - 08:05 am:

Too bad there are going to be "secrets" here, especially Renata´s second question is intriguing.
Some thirty years ago chiral TLC failed us and I have never tried anything of this sort since, thus I don´t know much about chiral chromatography. "Theoretically" I would be inclined to come to the assumption that assignment of absolute configuration would be difficult if not impossible (if it has not already been established under those conditions, or without a polarimeter, CD or optical rotatory dispersion?).

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By Renata on Thursday, July 8, 2004 - 09:18 am:

Hi Henz,

you can write the method down in the forum, if you feel comfortable of course, in order of not having "secrets" here. :o)

sorry HW Mueller, it was not my intention!

Renata Amaral

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By B.Buglio on Thursday, July 8, 2004 - 06:08 pm:

The USP method is a RP method:doesnt separate the
enantiomers. There are, however, chiral
separations available - Astec's Chirobiotic V
column achieves virtually baseline separation and
I believe Daicel has a column which will also
separate the isomers.

A phone call to either company will provide the
optimal conditions and likely which enantiomer
elutes first.

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By Antje on Friday, July 9, 2004 - 05:01 am:

Hi Renata,
there is a method on a DAICEL Chiralcel OD colum for the enantiomeric separation of ibuprofen. The mobile Phase is n-Hexane/2-propanol/CF3COOH = 100/1/0.1 at 254 nm and a flow of 1 ml/min. I don't know, wich enantiomer elutes first. Die USP substance is a racemic ibuprofen.

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By Renata on Monday, July 12, 2004 - 06:44 am:

Thanks for all

Renata Amaral