Thermo Finnigan LTQ - 1.1 Ion Polarity Modes

Introduction
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______________________________________________________________ Ion Polarity Modes
_______________________ Finnigan LTQ Hardware Manual ______________________
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1.1 Ion Polarity Modes
You can operate the LTQ in either of two ion polarity modes: positive or
negative. The LTQ can control whether positive ions or negative ions are
transmitted to the mass analyzer for mass analysis by changing the polarity of
the potentials applied to the API source and ion optics. The ion optics are
located between the API source and the mass analyzer.
The information obtained from a positive-ion mass spectrum is different from
and complementary to that obtained from a negative-ion spectrum. Thus, the
ability to obtain both positive-ion and negative-ion mass spectra aids you in
the qualitative analysis of your sample. You can choose the ion polarity mode
and ionization technique to obtain maximum sensitivity for the particular
analysis of interest.