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Why do Int Stnds not need reference ions In MRM LCMS?
Posted: Mon May 12, 2014 4:54 pm
by PeterPopoff
Why is it that when I look at a premade method that for a specific compound it uses the target and reference ions to identify it, but for its dueterated internal standard there is only one peak, ie, not reference ions peaks? I know this is probably a dumb question but thanks.
Re: Why do Int Stnds not need reference ions In MRM LCMS?
Posted: Tue May 13, 2014 3:10 pm
by MaryCarson
The reference ions are there to confirm that you found the compound you think you found. Not needed for the I.S. because you KNOW it's there--after all, you added it to the sample.
Re: Why do Int Stnds not need reference ions In MRM LCMS?
Posted: Tue May 13, 2014 4:04 pm
by James_Ball
I usually build my own methods for LCMSMS and I include the second ion for the Internal Standards just for extra insurance there are no problems with the analysis. I have seen a lot of methods posted the do not use them, but coming from EPA GCMS background it have always just carried over the fact you have to have them.