Modern MALDI time-of-flight mass spectrometry

This paper focuses on development of time-of-flight (TOF) mass spectrometry in response to the invention of matrix-assisted laser desorption/ionization (MALDI). Before this breakthrough ionization technique for nonvolatile molecules, TOF was generally considered as a useful tool for exotic studies of ion properties but was not widely applied to analytical problems. Improved TOF instruments and software that allow the full potential power of MALDI to be applied to difficult biological applications are described. A theoretical approach to the design and optimization of MALDI-TOF instruments for particular applications is presented. Experimental data are provided that are in excellent agreement with theoretical predictions of resolving power and mass accuracy. Data on sensitivity and dynamic range using kilohertz laser rates are also summarized. These results indicate that combinations of high-performance MALDI-TOF and TOF-TOF with off-line high-capacity separations may ultimately provide throughput and dynamic range several orders of magnitude greater than those currently available with electrospray LC-MS and MS-MS.