2 questions:
1) Given that a dissolution profile for modified release tablets is to be determined via repeated sampling of dissolution vessels (eg. 7 samples of 10mL each drawn at intervals spanning 8-12 hours) and that said samples are to be analyzed by HPLC, how do you typically correct for the API removed in previous samples?
For example - using external standard calculations, we have typically expressed the sample area for the nth sample as a function of its fraction of the whole volume (500mL in this case) and expressed the 1 through n-1 sample areas proportionately:

disscor.htm disscorr.html (<1 k)

Meybe you should ask it at a dissolution forum,eg:
http://www.dissolution.com/vbulletin/index.php

There are ways to accomodate the loss in dissolution media. The Waters dissolution system can add media back into the system or you calculate the loss of media as you stated. I honestly don't know how you correct for the API that is lost.

I have only ever used Millennium for calculations and it is easy to do custom calculations. They also have a special dissolution option that makes it easy to calcualte release profiles.

I'm sorry I couldn't help more.

I checked http://www.dissolution.com/vbulletin/index.php and found calculations similar to what I presented above, but they replace media (we don't). Maybe I'll post my question there when I get my registration activated.

Thanks for the suggestions (so far).

DR,

We correct all dissolution calculations for both the amount of material removed and the volume removed. I think this is standard practice. Intersample calculations are tough inside of a CDS because you need the result from the first hour to calculate the second hour result. If you adjust the integration on one sample it affects the results of other samples.

The Millennium system can do this IF you do dissolution the way Millennium knows about. Forget about media replacement, etc. Otherwise intersample calculations are still not available as of version 4.0. I haven't used turbochrome recently. My guess is that you will probably be exporting to Excel. E-mail me if you want me to check your calculations. Good luck.

Tom Mizukami,

Do you try to resolve problems of users or you $$$, only?

Anon,

I don't understand your comment. I have never solicited or offered any paid service to anyone in this forum. I was offering to check the spreadsheet or whatever.

Hi Tom

Thanks for your advice..I've learned alot from Tom and everybody else who is willing to share their knowledge/experience with the forum. Keep it up Tom.

Anon 21 okt,

I guess you haaven't heard of gentlemens or such things, if you want some help, you can ask it friendly, I have had some e-mail contact with Tom in the past, and I have none bad word for his manner of work. I guess you haven't contact him before you add such crap on the forum.

So Tom, keep up the good work!

Why would anyone make such an accusation about Tom M.? He is a always a great contributor to this forum. Keep up the good work.

I guess I just don't understand people.

Melissa

Thanks for the kind words.

Sorry, but one more Tom comment here: I have always found his advice, knowledge, and over-all good-guy-ness to be first rate, and one of if not the most informative and helpful posters here. Thanks, Tom.