Question

Suppose that you have a time-of-flight mass spectrometer with a detector that can clearly resolve ion signs that are at least 14.0 nanoseconds apart in arrival time. Given a flight tube length of 1.40 m total field-free distance from source to detector, and a source with an acceleration voltage that extends over a 2.5 cm distance,

a) determine the source voltage required to ensure that two proteins with masses 2237.5 amu and 2239.8 amu are adequately resolved, i.e. have a flight time difference of 14 ns. Assume that all ions gain the full source energy possible, and that there is no temporal spread in the ion signal.

b) Assuming that the electric field is 2.400 kV m-1, determine the minimum length of field-free flight that would be required to resolve these two ions. (Note: Be sure to convert the electric field to a applied voltage!)

Answer 1