What does TOF stand for in MALDI-TOF?
MALDI-TOF combines matrix-assisted laser desorption ionization with time-of-flight analyzer for rapid, sensitive mass analysis of biomolecules. TOF specifically represents time of flight, describing physical principle separating ions after desorption. After laser pulse, ions acquire nearly equal kinetic energy and travel through a field-free drift tube. Velocity inversely relates to square root of m/z, so lighter ions reach detector earlier than heavier ions. Precise measurement of flight time yields accurate m/z determination. This terminology distinguishes this analyzer from quadrupole or Orbitrap systems and explains its wide mass range for proteins and polymers.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.