Two different measures of sensitivity are recommended. The first, which is suitable
for relatively involatile materials as well as gases, depends upon the observed change
in ion current for a particular amount or change of flow rate of sample though the
ion source. A second method of stating sensitivity, that is most suitable for gases,
depends upon the change of ion current related to the change of
partial pressure of the sample in the ion source. It is important that the relevant experimental conditions
corresponding to sensitivity measurement should always be stated. These include in
a typical case details of the instrument type, bombarding electron current, slit dimensions,
angular
collimation, gain of the multiplier detector, scan speed and whether the measured signal corresponds
to a single mass peak or to the ion beam integrated over all masses. Some indication
of the time involved in the determination should be given, e.g. counting time or band
width. The sensitivity should be differentiated from the
detection limit.
Source:
PAC, 1991, 63, 1541
(Recommendations for nomenclature and symbolism for mass spectroscopy (including an
appendix of terms used in vacuum technology). (Recommendations 1991))
on page 1553