Chromatography Forum

I am looking for an assay method suitable for determination of imidurea purity.

I have a colorimetric method that provides reasonable results with a skilled analyst, but suffers from sensitivity to timing and reagent instability.

I would prefer to obtain an HPLC method that we could validate for release testing.

There were some posts on the old web site that suggested others were performing similar testing, but the links are no longer available. I would appreicate any assistance possible.

Thank you for your suggestions.

This looks ideal for HILIC, and rather straightforward. Use a silica HILIC column (Atlantis HILIC Silica) with a mobile phase of 70% acetonitrile and 30% water, detection in low-UV.

Also possible to use Hamilton PRP X100 column and high pH, eg

http://www.bgb-shop.de/pdf.php?productid=52

Bruce Hamilton

Uwe,
Do you have any information on actually determining imidurea under HILIC condtions or is this something that looks within the range of target molecules? I have not had much success with HILIC and need more tutoring to become a HILIC user.

Bruce,
I have worked with Hamilton columns and have found all the methods work as described, even if the sensitivity is not a high as we might like sometimes.

I would rather work with either HPLC method since I know I can control sensitivity by sample preparation and control of the sample concentration so long as I don't overload the column. The colorimetric method is designed for low ppm concentrations and appears to be air-sensitive at some stages of the testing. All of this is controlled with an HPLC method.

Does anyone know the chemistry of the colorimtric Nash method for reaction of 2,4-pentanedione with imidurea to determine the midurea? According the technical support people, it is supposed to be forming lutidine, but that isn't consistent with the colorimetric determination of imidurea, since lutidine is not colored adn the method measures the material at 410 nm. It would help know how to improve the precision if we know what we were measuring!

Thanks to both of you for your input. I think we will end up moving this to an HPLC method eventually. It will jsut take more research.

For an analyte like this, HILIC is very straightforward. The compound is very polar, comparable to a sugar, and essentially non-ionic. This is the reason why I suggested HILIC. What would be of interest for the method development is if any impurities are ionic in nature, which would require some pH control in addition to the 70/30 acetonitrile/water. If they are all non-ionic, then it should be easy.

The colorimetric analysis for Imidurea (Germall 115) is mentioned in some of the previous posts. Does anyone have a copy of that to share?