Construction and Performance Test of a Multiplexed Multistage (MSn) Time-of-Flight Mass Spectrometer

A time-of-flight mass spectrometer equipped with two reflectrons was constructed for multiplexed photodissociation tandem mass spectrometry of peptide ions generated by matrix-assisted laser desorption ionization. A linear reflectron was used for high-resolution selection of a precursor ion while a quadratic reflectron was used for product ion analysis. With the photoexcitation of a precursor ion inside a cell floated at high voltage, information (MS(3)) on intermediate ions generating a particular product ion was obtained. Fully multiplexed detection resulted in good MS(3) signal levels. Use of the quadratic reflectron allowed intermediate ion mass determination within 4 Da. The possibility of further extending the technique and its analytical potential are discussed.