In MALDI-TOF mass spectrometry, what does the TOF in the acronym stand for?

• A. Time Of Flight
• B. Type Of Frequency
• C. Transfer Of Fragment
• D. Test Of Function

Answer: (A)

The concept being tested is how the acronym TOF is defined in MALDI-TOF mass spectrometry. TOF stands for Time Of Flight. In this technique, ions created by MALDI are accelerated into a flight tube under a uniform electric field. Since all ions receive the same amount of kinetic energy, lighter ions travel faster than heavier ones. The time it takes for an ion to reach the detector—the flight time—depends on its mass-to-charge ratio. By measuring these flight times, the instrument determines m/z values and builds a mass spectrum used to identify organisms. The other options describe terms that aren’t used in this context (Type Of Frequency, Transfer Of Fragment, Test Of Function), so they don’t fit with how MALDI-TOF operates.