Figure 1.

Basic principles of matrix-assisted laser desorption/ionisation (MALDI) time-of-flight (TOF) mass spectrometry. Following ionisation, sample ions are accelerated into an electric field free “drift” region. The larger the ion the less energy it will gain during acceleration and as a result it will travel slower than smaller ions. This is the basis of time of flight separation. Time from laser ionisation to detection at the opposite end of the drift region is used to determine mass to charge ratio (m/z) for masses between 0–300 kDa. High mass accuracy is achieved using a reflector field that focuses ions from 0–6 kDa onto a secondary detector.