Electrospray interface cycle time with

One reason for lower sensitivity is the lack of flexibility to optimize the positions of the sprayers on the MUX interface another may be the lower electrospray desolvation efficiency on the MUX. The longer total cycle time on a MUX interface with a quadrupole MS in comparison to a single sprayer interface adds another concern. Assuming typical chromatographic peak widths appeared on average at 15 sec, 17 data points could be easily detected across the peak for each transition with a total cycle time of 0.88 sec on a conventional single sprayer set-up. With the MUX, only 12 data points could be detected across the same peak even with a total cycle time of 1.24 sec because of the introduction of additional interspray time on top of dwell time. Hence, when MUX is used with a quadrupole mass analyzer, it is important to consider dwell time and chromatographic peak width... 

A TOF mass analyser requires a pulsed ion introduction. In an electrospray-TOF combination, the duty cycle is an important issue. A significant improvement in the duty cycle can be achieved in an ion-trap-TOF hybrid instmment the ions from a continuous ion source are accumulated in the ion trap between two ion introduction events. An ion-trap-TOF hybrid instrument was first described by the group of Lubman [68-69]. The system consists of an atmospheric-pressure ion source with a vacuum interface, a set of Einzel lenses, an ion-trap device, and a reflectron time-of-flight mass analyser. The system was applied for fast analysis in combination with a variety of separation techniques [70]. 

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