High efficiency MALDI-QIT-ToF mass spectrometer

A novel mass spectrometer comprising a Matrix Assisted Laser Desorption/Ionisation (MALDI) source, a Quadrupole Ion Trap (QIT) and a Reflectron Time of Flight (reToF) Mass Spectrometer (MS) has been developed. Computer simulations have been carried out to model different methods for efficiently introducing MALDI ions into the QIT and for subsequently extracting ions from the QIT to a dual-stage gridless reToF. The parameters for the system were optimised to get near 100% trapping efficiency and the highest mass resolution. A prototype instrument was built to realise the performance predicted from the computer simulations. Methods for the near orthogonal laser irradiation of a sample, fast switching of large amplitude Radio Frequency (RF) voltages and a gridless dual-stage reflectron were developed. These new developments were combined with a number of other already known techniques to provide the facility to perform high efficiency ion trapping and MS/MS and higher (MSn) analysis. High mass spectra for m/z up to 16,000 have been obtained, and MS3 experiments have been successfully carried out. A sensitivity of 0.1 fmol has been achieved at a mass resolution exceeding 3,000.