1
Introduction
2 TSQ Series Hardware Manual Thermo Scientific
as the ionization mode. The ion optics transmit the ions produced in the ion source into the
mass analyzer, where they are separated according to their mass-to-charge ratio. The polarity
of the potentials applied to the lenses in the ion source and ion optics determines whether
they transmit positively charged ions or negatively charged ions to the mass analyzer. You can
configure the TSQ mass spectrometer to analyze positively or negatively charged ions (called
the positive or negative ion polarity mode).
The TSQ instrument’s triple-stage mass analyzer performs either one or two stages of mass
analysis:
• The TSQ system is operated as a conventional mass spectrometer with one stage of mass
analysis. The ion source ionizes the sample and the ion products are subjected to mass
analysis in the first rod assembly. The second and third rod assemblies transmit the
resulting mass-selected ions to the ion detection system.
1
• The TSQ system is operated as a tandem mass spectrometer with two stages of mass
analysis. The ion source ionizes the sample and the ion products are mass analyzed by the
first rod assembly. In this case, however, mass-selected ions exiting the first rod assembly
collide with an inert gas in the second rod assembly and fragment to produce a set of ions
known as product ions. (A chamber called the collision cell surrounds the second rod
assembly. The collision cell can be pressurized with an inert gas.) The product ions
undergo further mass analysis in the third rod assembly to detect selected ions. Two stages
of mass analysis yield far greater chemical specificity than a single stage can achieve,
because of the system’s ability to select and determine two discrete but directly related sets
of masses.
In a first stage of mass analysis the TSQ systems can be used to elucidate the structures of pure
organic compounds and the structures of the components within mixtures. Furthermore, in a
second stage of mass analysis, the mass spectrometer can fragment and separate each ionic
fragment of a molecule formed in the ion source to build up an entire structure for the
molecule, piece by piece. Thus, TSQ systems make investigating all pathways for the
formation and fragmentation of each ion in the mass spectrum possible.
The two stages of mass analysis, with resultant reduction of chemical noise in the final mass
spectrum, allow for very selective and sensitive analysis.
Each sequence of single- or triple-stage mass analysis of the ions is called a scan. The TSQ
mass spectrometer uses several different scan modes and different scan types to filter,
fragment, or transmit ions in the mass analyzer. Along with the ionization and ion polarity
modes, the ability to vary the scan mode and scan type affords the user great flexibility in the
instrumentation for solving complex analytical problems.
1
The instrument can also be used as a single-stage mass spectrometer by transmitting the ions through the first
and second rod assemblies followed by mass analysis in the third rod assembly.
To Next Page
Loading...
Need help?
General
