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HPLC analysis - Retention time of a API and its salt form

Posted: Thu Aug 23, 2012 8:45 am
by rickmartink
Dear all

In HPLC analysis will the Base and Its salt form of a API have the Same RT or different RT. Eg. Omeprazole and Omeprazole Magnesium with these two have same RT during HPLC run or different RT.

Pl. advice

Re: HPLC analysis - Retention time of a API and its salt for

Posted: Thu Aug 23, 2012 1:07 pm
by prepcolumn
it will be same

Re: HPLC analysis - Retention time of a API and its salt for

Posted: Thu Aug 23, 2012 2:40 pm
by rickmartink
it will be same
Thanks
then how do i differentiate or know in a blind sample ( placebo mixture containing either omeprazole or omeprazole Magnesium) whether it has omeprazole mag. or Omeprazole.

Re: HPLC analysis - Retention time of a API and its salt for

Posted: Thu Aug 23, 2012 4:35 pm
by tom jupille
Measure Mg++

Re: HPLC analysis - Retention time of a API and its salt for

Posted: Thu Aug 23, 2012 5:05 pm
by Vlad Orlovsky
You need to quantify both counter-ions and calculate content of free base and salt. Actually you molecule is basic and Mg ion is basic. Is it part of formulation?

You can do both using reversed-phase cation-exchange column. You will need ELSD/CAD for Mg determination:
http://www.sielc.com/upload/file/pdf/SI ... y_2009.pdf