LCMS study of drug metabolite Rabiprazole

[mariojon]

Hello,

This is just a query because Iam concerned about the safety of the LC-MS system we have. Anyway here goes the question.
Can anybody tell me about LC-MS of drug metabolites studies?

I have a sample of rabiprazole which is dissolved in phosphate buffer 7.0 . Can i do LCMS study on it or will there be trouble with ionization or ion suppression? My MS system is waters zq4000.

Thank you[/

[yangz00g]

It's common sense to avoid non-volatile buffer for API instrument. You denifility will oberserve some trouble with phosphate buffer.

[Uwe Neue]

Well, it is DISSOLVED in phosphate buffer...

For one thing, the amount of phosphate that ends up on the interface is related to the sample volume that you are injecting. So it could very well be that it is so small that you should not be concerned. However, there is another trick that you can use: the phosphate injected will elute as an unretained peak, and you can switch your mobile phase to the MS after it has eluted from the column. You need to set up your system with a post-column switcheng valve, of course.

[yangz00g]

Capital DISSOLVED means "only dissolved", no other buffer can be used? Sorry, I don't know that.

It should be OK with phosphate if you only run a limited number of samples. Many samples combined with Water's Z-Spary? I really doubt.

[Uwe Neue]

Well, I used to run pH 7 ammonium phosphate buffer as the MOBILE PHASE with the Z-spray. I do not recommend to do this, but it is possible to do so for weeks. Of course, at some point you will need to do some cleaning....