De Maldi-Tof Ms.
MALDI-MS lacks resolution and sensitivity to analyze complex mixtures like those of Sanger’s sequencing reaction mixture. This is because the initial velocities and therefore also the range of flight times of ions of the same mass extracted in Conventional MALDI TOF MS, may differ due to a variety of reasons thus reducing the resolution of the technique. Improvements have been made by varying the time between formation and extraction of ions from the source.

The ion source may be field free during ionization and only after a specified time delay, a high amplitude pulse of irradiation extracts ions.This results in the arrival of ions of the same mass simultaneously at the detector and helps in correlating the velocity differences in ions with their masses thus improving the resolution of a time of flight (TOF) mass analyzer. The technique is described as delayed extraction MALDI (DE MALDI) and has been used for DNA sequencing.