A concept of an "ideal" orthogonal-injection time-of-flight (O-TOF) mass sp
ectrometer is proposed and a new high-resolution O-TOF mass spectrometer wi
th an electrospray ion source and a molecule-ion reactor is described. The
instrument design was optimized for high resolution and sensitivity using t
he concept of an ideal O-TOF mass spectrometer. A mass resolving power of a
bout 20,000 (full width at half maximum) and a mass measurement accuracy in
the 10 ppm range is demonstrated.