Quadrupole in wide band-pass mode

With the Quadrupole in Wide Band-Pass Mode... 

Schematic diagram of an orthogonal Q/TOF instrument. In this example, an ion beam is produced by electrospray ionization. The solution can be an effluent from a liquid chromatography column or simply a solution of an analyte. The sampling cone and the skimmer help to separate analyte ions from solvent, The RF hexapoles cannot separate ions according to m/z values and are instead used to help confine the ions into a narrow beam. The quadrupole can be made to operate in two modes. In one (wide band-pass mode), all of the ion beam passes through. In the other (narrow band-pass mode), only ions selected according to m/z value are allowed through. In narrow band-pass mode, the gas pressure in the middle hexapole is increased so that ions selected in the quadrupole are caused to fragment following collisions with gas molecules. In both modes, the TOF analyzer is used to produce the final mass spectrum.

In its RF-only configuration (wide band-pass mode), all ions produced in an ion source and accelerated gently into the quadrupole analyzer will pass through it, whatever their m/z values. In contrast, the RF/DC mode is selective for chosen m/z values. 

A hexapole assembly of rods (poles) is built similarly to the quadrupole, but now there are three sets of opposed rods evenly spaced around a central axis. The hexapole cannot act as a mass filter by applying a DC field and is used only in its all-RF mode. It is therefore a wide band-pass filter and is used to collimate an ion beam. (Like-charged particles repel each other, and an electrically charged beam will tend to spread apart because of mutual repulsion of ions unless steps are taken to reduce the effect.)... 

QTOF systems (also called QqTOF) are versatile configurations. The quadrupole may be used in either a wide or narrow band pass mode to determine which ions are passed into the collision region (q) and then into the time-of-flight analyzer (Figure 2.36). Full-scan MS data are obtained in the basic mode when the quadrupole... 

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