Time-of-flight hexapole

Hybrid Hexapole Time-of-Flight (Hexapole/TOF) Instruments... 

The term Q/TOF is used to describe a type of hybrid mass spectrometer system in which a quadrupole analyzer (Q) is used in conjunction with a time-of-flight analyzer (TOP). The use of two analyzers together (hybridized) provides distinct advantages that cannot be achieved by either analyzer individually. In the Q/TOF, the quadrupole is used in one of two modes to select the ions to be examined, and the TOF analyzer measures the actual mass spectrum. Hexapole assemblies are also used to help collimate the ion beams. The hybrid orthogonal Q/TOF instrument is illustrated in Figure 23.1. 

Common tandem-in-space instruments employ a quadrupole as the first mass analyzer, a multipole collision cell (usually hexapole) operated in RF-only mode, and then either a second quadrupole or a TOF tube as the second mass analyzer. These instruments are termed triple or tandem quadrupole and quadrupole-time-of-flight mass spectrometers. 

It should also be noted that the RF-only quadrupoles (as well as the related RF-only hexapoles and octapoles) can be operated as ion lenses, often referred to as RF-only ion guides or simply ion guides. RF-only quadrupoles (denoted as lower case q , nonitalicized, to distinguish them from the closely related quadrupole mass filters Q) also act as efficient collision cells for collision induced dissociation in triple quadrupole analyzers (QqQ, Section 6.4.3) and hybrid tandem quadrupole-time of flight instruments (QqTOF, Section 6.4.7). Discussion of these devices must be postponed imtil the principles of all hnear quadrupoles have been considered (Section 6.4.2). 

Guzowski j. P. and Hieettb G. M. (2001) Characteristics of an RE-only hexapole ion-guide interface for plasma-source time-of-flight mass spectrometry, J. Anal. At. Spectrom. 16 781-792. 

---