HPLC separation of enantiomers of the drug Ritalin on a chiral stationary phase was shown in Problem 24-11.

(a) Detection is by atmospheric pressure chemical ionization with selected reaction monitoring of the m/z 234 †’ 84 transition. Explain how this detection works and propose structures for m/z 234 and m/z 84.
(b) For quantitative analysis, the internal standard 2H3-Ritalin with a deuterated methyl group was added. Deuterated enantiomers have the same retention times as unlabeled enantiomers. Which selected reaction monitoring transition should be monitored to produce a chromatogram of the internal standard in which unlabeled Ritalin will be invisible?

Transcribed Image Text:

〔..。ご İlin (methylphenidate) H co.cH, Nominal mass = 233