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rosiglitazone
Posted: Fri Mar 24, 2006 5:15 pm
by zompa
Hi everybody,
Can anyone give any suggestion about the hplc method for Rosiglitazone?
I'm just starting...
NH4CH3COO 0.01M pH=7 60% CH3CN 40%.
Column Phenomenex Hexyl-Phenyl
Detector UV 254 nm
Good resolution... Anyway I'd like to know if anyone has developed anything to compare and make it better.
Thanks.
Posted: Sat Mar 25, 2006 12:53 am
by Uwe Neue
Don't start with ammonium acetate at pH 7, start with a buffer, i.e. ammonium acetate at pH 4.75.
Posted: Sat Mar 25, 2006 9:22 am
by zompa
thanks, Hue.
I'll try soon.
Posted: Sat Mar 25, 2006 9:23 am
by zompa
sorry.. I meant Uwe.
Posted: Sat Mar 25, 2006 10:45 am
by Rafael Chust
First of all, Uwe's suggestion is a very important rule of thumb. Always use a "controlled" buffer system and avoid a solution with stuff you might not control.
Second, like in football, if you have a good team, don't change it! And if you have a team good enough to win the championship, do not expend a fortune with a galactic player... chromatography translation: if you have a good separation with the right eluent system - preferably isocratic - STUCK TO IT!
Posted: Sat Mar 25, 2006 11:06 am
by zompa
Hi Rafael,
Good to hear from you..
I thought that NH4AcO buffer strength is max at around 7 because of the Ammonium, while if I had used Na+ it would have been 4.8.
Anyway, I found that the separation has to be improved.
I'm going to try 4.8 soon... I thought I'd sorted it out too soon.
If you have any suggestion please let me know.
Thanks.
Posted: Sat Mar 25, 2006 11:37 am
by zompa
Rafael,
Do you mind if I e-mail you?
Thank you.
Posted: Mon Mar 27, 2006 1:52 am
by syx
I thought that NH4AcO buffer strength is max at around 7 because of the Ammonium, while if I had used Na+ it would have been 4.8.
The pKa of ammonium (ammonia) is 9.2 and acetate is 4.8... Buffer is only effective within ±1 pH unit from its pKa. How could Zompa said that NH4OAc buffer strength is max at around 7?
Posted: Mon Mar 27, 2006 7:37 am
by Rafael Chust
Rafael,
Do you mind if I e-mail you?
Thank you.
No problem... since I made my e-mail "public", I do not mind any contact either by e-mail or MSM
Posted: Mon Mar 27, 2006 10:56 am
by zompa
Sorry everybody,
I was talking nonsense about the buffer power..
Zompa.