Mass analyzers, electrostatic quadrupole

Thermospray (TSP) [29-31] unites three modes of operation. In pure TSP, a solution of the analyte and a volatile buffer, usually 0.1 M ammonium acetate, is evaporated from a heated capillary at a flow rate of 1-2 ml min into a heated chamber, hence the term thermospray. As the solvent evaporates, the analyte is forming adducts with ions from the buffer salt. While most of the neutrals are removed by a vacuum pump, the ions are extracted orthogonally from their main axis of motion by use of an electrostatic potential. The ions are transferred into a quadrupole mass analyzer through a pinhole of about 25 pm in diameter (Fig. 11.2). The quadrupole was employed according to its tolerance to poor vac-... 

No one single mass analyzer is suitable for all applications and the choice of instrument is determined by the type of problem under investigation [68]. Double focusing magnetic/electrostatic sectorfield-, quadrupole-, quadrupole ion trap-, time-... 

Figure 1 Schematic drawing of an electrospray ionization (ESI) source and a triple-quadrupole mass analyzer. Ions are generated from the spray in the electrostatic field between the capillary and the counterelectrode. They are subsequently transmitted through a number of electrostatic lenses into the high-vacuum region of the first quadrupole mass analyzer (MS1). Optionally, ions selected by MSI can be fragmented by collision-induced dissociation (CIO) with gas (e.g., argon) in the collision cell and fragment ions analyzed in the second quadrupole mass analyzer (MS2). Representative residual pressures are indicated for the different regions of the instrument.

Fig. 6.11 A schematic drawing of new ion attachment mass spectrometer with the capillary sample inlet and a vacuum envelope with a wall separating ELS chamber fiom mass analyzer chamber. This capillary inlet is fixed on the front flange of the vacuum envelope. 1C ionization chamber, ELS electrostatic lens system, QMS quadrupole mass spectrometer, TMP turbomolecular pump, RP rotary pump. The vacuum envelope is pumped by a single 230 L sec" turbomolecular pump with two ISO-100 inlet flanges (Pfeiffer-Vacuum TMH 261-250-010) plus a 250 mL min" rotary pump. Ionization chamber is closed-type, with a 1 mm < ) aperture through which ionic species are passed. The typical operating conditions are IS pressure with nitrogen gas used as a buffer gas, 40 Pa pressure of ELS chamber, 8x10" Pa, pressure of the QMS chamber, 8 xlO"" Pa. (Reprinted with permission from Ref. [93]. 2012, Springer)...

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