New time-of-flight mass spectrometer for improved mass resolution, versatility, and mass spectrometry/mass spectrometry studies

Abstract

Reported here is the design and experimental investigation of the performance characteristics of a new time-of-flight (TOF) mass spectrometer. The instrument combines the advantages of beam deflection for ion pulse formation with an electrostatic analyzer which reduces the energy spread of the ions admitted to the TOF region. The instrument is able to use ion sources which cannot be pulsed on a time scale suitable for conventional TOF analysis (e. g., chemical ionization sources). Improved mass resolution is demonstrated over a wide mass range such that all of the ions are in focus simultaneously. A resolution of 982 (full width at half-maximum) is achieved for the molecular ion peak of perfluorotributylamine at m/z 614. A preliminary investigation of a proposed technique for collecting information typically obtained by tandem mass spectrometry (MS/MS) has also been conducted using this instrument. This new method, named time-resolved ion kinetic energy spectrometry (TRIKES), combines time-of-flight (velocity) and kinetic energy analysis of undissociated parent ions and daughter ions which are products of decompositions occurring between the ion source and electrostatic analyzer. Unit resolution of the daughter ions produced upon metastable decomposition of the molecular ion of n-decane has been achieved in constant parent scans. The realization of rapid time-of-flight data collection rates in TRIKES may yield improved data collection rates in MS/MS.