Improving the sensitivity of the end-cap reflectron time-of-flight mass spectrometer

A miniaturized time-of-flight (TOF) mass spectrometer utilizes an end-cap r eflectron to achieve high kinetic energy focusing and improved mass resolut ion. However, the coaxial geometry gives rise to considerable losses in sen sitivity resulting from reflected ion trajectories close to the center. The se trajectories were modeled, using initial ion velocity distributions in t he radial direction up to 300 m s(-1), and the portion of the active area o f the detector that is utilized was evaluated experimentally using a variab le diameter iris diaphragm. The sensitivity was improved by modification of the reflectron by tilting the end-cap electrode 4 degrees and redirecting the ions to a portion of the detector active area. Sensitivity was then mea sured as 3 fmol of the peptide substance P. Copyright (C) 2000 John Wiley & Sons, Ltd.