Figure 1: Schematic diagram of a MALDI TOF MS. (A) Mass spectrometer equipped with a N2- or neodym YAG laser, an attenuator, a target, an acceleration electrode and a detector. The laser emits energy pulses towards the target, while the attenuator between the laser and the target allows tuning of the laser energy. The MALDI target is a metallic plate providing space for 16 384 samples. Due to the laser excitation, proteins are desorbed and ionized. The resulting ions are accelerated in an electric field (about 20 kV) and drift through the flight tube until registered by the detector. The ions may reach the detector directly (linear mode) (B) or after been rejected from a reflector (reflection mode) (C). The time of flight is measured and the m/z can be calculated. The whole system is operated under high vacuum.