Bioequivalence and Bioavailability Forum • Whether to consider Monovalent or Bivalent molecular weight

pmgjoshi
☆

India,
2009-04-13 11:40
(6279 d 01:30 ago)

Posting: # 3514
Views: 3,363

Whether to consider Monovalent or Bivalent molecular weight [Bioanalytics]

Dear all,
I have done one study in which the lable claim of the Drug tablet is of Bivalent salt of Zolpidem (Zolpidem Tartarate). For the preparation of stock solution I have considered Monovalent molecular weight.
The analysis was done on HPLC (with UV detector).
1. The counterpart (sponsor) is asking us to consider the bivalent molecular weight. But as per the FDA recommondations parent ion should be measured and
we have done the same. So, what is the right method?
2. This was the case with the UV-HPLC as a detector. If it would have been LC-MS/MS, as per the basics of Mass spectometry I had to consider actual molecular weight of the Monovalent.
So, should we consider Monovalent weight irrespective of the analytical technique?
Best regards,
Prashant

babun14
☆

2009-04-14 12:55
(6278 d 00:16 ago)

@ pmgjoshi
Posting: # 3520
Views: 2,701

Whether to consider Monovalent or Bivalent molecular weight

Post reply

Dear Prashant,

You should consider the no. of free analyte present in the salt for the calculation purpose. So, in this partcular case the conc. would be double to what you have used for quantification purpose.

The formula for conc. is =(amount of salt weighed/total volume )*(mol. weight of free analyte/Mol. wt. of salt)*no. of free analyte

Hope this will help you.

regards

Bani

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Edit: Full quote removed. Please see this post! Helmut

pmgjoshi ☆ India, 2009-04-16 09:13 (6276 d 03:57 ago) @ babun14 Posting: # 3543 Views: 2,630	Whether to consider Monovalent or Bivalent molecular weight Post reply
	Dear Bani, Thanks you soo much..