The development of reflector time-of-flight (TOF) mass analyzers, delayed extraction (DE) on a matrix assisted laser desorption (MALDI) source, as well as other high resolution (HR) mass spectrometers resulted in superior mass resolution for newer mass spectrometers that are now commercially available.
For more info please review the article from Pleil and Isaacs (2016).
For the history of mass spectrometry review "About ASMS and MS History."
Important performance factors to look for in a mass spectrometry instrument:
Mass accuracy: How accurate is the mass measurement?
Resolution: How well separated are the peaks from each other?
Also review: Tandem Mass Spectrometry and Protein Sequencing.
A few companies that offer Mass Spectrometry Solutions are: