Differential mobility spectrometer as an ion/molecule reactor: Peptide H–D exchange in mobility separation

• Enhanced performance of DMS-MS by including H–D exchange.
• Deconvoluted ion isomers not distinguishable by ion mobility alone.
• Bradykinin, a model tryptic peptide, and hexaglycine are used as sample analytes.
• Relative reaction kinetics measured for peptide ion H–D exchange with D2O and CH3OD.

H–D exchange reactions have been exploited to improve the performance of a differential mobility spectrometer (DMS) coupled to a triple quadrupole mass spectrometer by deconvoluting ion isomers otherwise not distinguishable by ion mobility alone. Bradykinin, a model tryptic peptide known to possess gas-phase isomeric structures, and hexaglycine are used as sample analytes. Demonstrated are peptide ion H–D exchange with D2O and CH3OD, including relative reaction kinetics measurements, and the separation of bradykinin isomers through the use of D2O/hexanol and CH3OD/hexanol modifier mixtures, where H–D exchange is combined with the superior mobility separation provided by hexanol. The modifier mixture allows the ion separation by differential ion mobility to be independent of the separation provided by the H–D exchange reagent.

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