HPLC method for Ziprasidone

[N.V.V.S.S. RAMAN]

Hai Friends,

I am getting trouble while developing HPLC method for this molecule. There is no problem with elution. The problem is the resolution between the peaks after tailing. I am getting 3 peaks on tail of the principal peak. Because of the very very poor resolution, I could not able to quantify or even I unable to show the repeatability of the % of these impurities.

I am using triethylammonium phosphate buffer and acetonitrile and tried with C8 and C18 columns.
Also I tried with TBAHS one of the reagent in buffer.
Can anybody suggest how to resolve this problem

Regards,

Raman

[Uwe Neue]

Try methanol instead of acetonitrile!
Also, what is the pH?

[N.V.V.S.S. RAMAN]

Hai Uwe,

The pH of the buffer I am using is 3.5

Also I tried with Methanol. The tailing of principal peak is increased.

Raman

[Uwe Neue]

You can try to play with the pH. Maybe pH 2.5 gives you a slightly different result than pH 3.5. Or even better go to pH 7 and see what is happening. Then try methanol again.

This is not dissimilar to the standard method development approach in my book.