beta keto esters by HPLC

[Santosh Gandhi]

Hello,
beta keto esters gives very bad peak shape by RP HPLC this is due to the keto-enol tautomerism.I found a article where mixed mode columns (SIELC) has been used for analysis. Are there any other mode by which proper peak shape can be obtained for these compounds.


Santosh

[tom jupille]

If the problem is really due to tautomerism, try increasing the temperature. The idea is to speed up the interconversion so that the system "sees" essentially one average state. That's a trick that's commonly used to overcome the analogous problem with mutarotation of sugars.

[SIELC_Tech]

Here is article published by Pfizer scientists. They used Primesep mixed-mode columns. They tried various traditional approaches and got the same problem as you have:

"Beta-diketones: peak shape challenges and the use of mixed-mode high-performance liquid chromatography methodology to obtain fast, high resolution chromatography". by Rance MJ, Wilson S. in Journal of Chromatography A Volume 1217, Issue 12, 19 March 2010, Pages 1912-1915.

Contact me by email if you have questions.

[HW Mueller]

Also, tautomerism is usually strongly influenced by pH, I would think that an acidic mobile phase should speed up the reaction sufficiently.