Time of Flight and QqTOF Analyzers

Time of flight analyzers (TOFs) are important in two main areas, as high m/z analyzers for ions produced by MALDI and as analyzers of medium resolving power that can provide mass measurements for low mass ions to within a few ppm. They are available either in stand-alone single TOF arrangements, or hybrid tandem QqTOF or TOF-TOF arrangements. Use of any of these instruments for quantitation is really their secondary application, with the exception of GC/TOF instruments that were specifically designed for fast capillary GC. 

The TOF analyzer was first described by Cameron and Eggers (Cameron 1948), but useful performance characteristics were not obtained till the work of WUey and McLaren some years later (Wiley 1955). In the context 

Thus if the flight time tf, can be measured, a simple transformation (or more usually in practice, a calibration) will 

However, when applied to chemical analysis conditions other than those approximating static SIMS, such a primitive instrument gives very poor resolving power in practice as a result of a distribution of values of Vx- In most cases the neutral analyte molecules and/or ions occupy 

Now make another simplifying assumption, i.e., that the average speed of the ion during its journey into the reflection is the simple average of its initial (vx) and final (0) values, i.e., Vx Then the flight time 

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