Selected ion flow tube mass-spectrometry is a technique for the real time quantification of trace gases in air and breath. The limit of quantification is currently about 10 parts per billion by volume (ppbv).
However to extend the range of analytical capabilities much better sensitivity with a detection limit of 0.01-0.1 ppbv is needed. The first step for increasing sensitivity of SIFT-MS is the optimisation of the injection quadrupole resulting in higher ion signal injected from the ion source into the flow tube reactor.
This goal can be achieved by the improved focusing using ion optical lens voltages that would result into optimum ion trajectories and ultimately by optimisation of the geometry of ion optics.