electrospray ionisation time-of-flight mass spectrometry high-resolution electrospray ionisation time-of-flight mass spectrometry HR-ESI-TOF-MS 2009-10-21T06:18:50Z ESI-HR-TOF-MS high-resolution electrospray ionization time-of-flight mass spectrometry https://orcid.org/0000-0001-5985-7429 CHMO:0002541 HR ESI TOF MS Mass spectrometry where the sample is ionised by forcing a solution (usually in an organic solvent) of the sample through a small heated capillary (at a flow rate of 1–10 L min-1) into an electric field to produce a very fine mist of charged droplets, and where sample ions with different masses are accelerated to the same (known) kinetic energy and the time taken for each ion to reach a detector at a known distance is measured. This time is dependent on the mass-to-charge ratio of the ion and the 'exact' mass of the molecular ions in the sample is determined as opposed to the 'nominal' mass (the number of protons and neutrons).