PulsedTOF

PulsedTOF refers to time-of-flight mass spectrometry methods that use short ionization or extraction pulses to create discrete packets of ions. The mass-to-charge ratio is inferred from the time it takes ions to traverse a field-free drift region after being accelerated by a pulsed electric field. The technique contrasts with continuous-mode TOF systems.

In a typical pulsed TOF instrument, ions are produced by a pulsed source (commonly MALDI or laser ablation) and immediately accelerated into a field-free flight tube. A reflectron may be used to compensate for kinetic energy spread and improve resolution. Detection is by fast solid-state or microchannel-plate detectors with timing electronics. The arrival time t scales with the square root of m/z, enabling mass assignment after calibration. Short, well-defined pulses and stable extraction voltages are essential for high-resolution measurements.

The most widespread form is MALDI-TOF for biomolecules such as peptides and proteins, as well as polymers and small molecules. Pulsed TOF instruments can be configured for tandem MS (TOF/TOF) for sequence analysis, and they are common in clinical microbiology, proteomics, and imaging mass spectrometry.

Advantages include fast analysis, broad mass range, and high sensitivity with relatively simple sample preparation. Limitations include matrix effects in MALDI, calibration drift, limited dynamic range, and that high-resolution analysis requires careful instrument tuning and, in some configurations, longer acquisition times. PulsedTOF remains a foundational technique in laboratories requiring rapid, versatile mass analysis across a wide mass range.