By Anonymous on Monday, June 7, 2004 - 07:21 am:

Hi, there,

I just wonder whether anyone has some experience in the LogD measurement of drug candidates. In my lab, we met the problem, some LogD is very high, we could not detect the drug concentration in the aqueous phase. We use shake flask method, because of our system limitation, we did not plan to go to lower column. And the method is applied to high throughput screen. So we could not get large quantity of test article to test.

So we are thinking using Ion Trap to detect the drug chemicals in the aqueous phase by TIC. However, I found some blank also have "huge" area in the same retention time as our drug article. Since MS is so sensitive, it detects anything that is ionizated at that retentin moment.

I just wonder whether anyone has ever used this method, what statistics did you get? I mean how accurate the result is in avaerage?

thanks so much!!!!!

jin

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By MG on Monday, June 7, 2004 - 07:38 am:

If you have an ion trap, I recommend MS/MS on the parent ion of your analyte, rather than TIC of a full scan run. Process your MS/MS data to get an extracted ion chromatogram of the daughter ion of your analyte, and quantitate from this. Alternately, run an isolation-only step on the daughter ion after the first MS/MS experiment, then you could use the "TIC" (which would only consist of the daughter ion). The latter experiment will lenghthen the duty-cycle and give fewer points across the peak, however.

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By Anonymous on Monday, June 7, 2004 - 08:40 am:

thanks so much, MG!!!

jin