Parallel Reactions for Enantiomeric Quantification of Peptides by Mass Spectrometry

Independent parallel ion/molecule reactions and fast dissociation have been used to quantify small enantiomeric excesses of dipeptides in a new mass-spectrometric method. The ee values are determined by simply mixing the analyte with CuCl2 and a chiral reference compound (ref*) in aqueous methanol and observing the relative abundances of the diastereomeric cluster ions (see scheme).