INFICON HAPSITE ER Chemical Identification System - Manual (Page 227)

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HAPSITE ER Operating Manual
Chapter 7
Tune
7.1 Introduction to AutoTune and Manual Tune
Ensuring the Mass Spectrometer (MS) performance requires a functionality check
at start-up and after 12 hours of continuous operation. The process of verifying the
Mass Spectrometer functionality is called Tuning. Tuning can be accomplished by
the AutoTune program, where the system sets and adjust all parameters, or by a
Manual Tune where the user sets the parameters.
The tune of a MS determines the quality of the mass spectrum produced by the
system. A good quality spectrum is one which matches either the reference
spectrum from the National Institutes of Standards and Technology (NIST) library
to give high Similarity Indexes, or the Automated Mass Spectral De-convolution
and Identification Software (AMDIS) libraries to provide high NET matches.
The Tune File contains the parameters that control the MS and is linked to a data
acquisition method. Multiple Tune files can be created for specific methods and
requirements. However, the default Tune is generally all that is required. The
default Tune is stored on the HAPSITE as
default.tun .
The parameters set in Tune that affect the quality of the spectrum include:
Base Peak Gain . . . . . . . . . . . . . . . Sets the sensitivity level of the MS.
Mass Axis Calibration . . . . . . . . . . Mass Spectrometers measure Atomic Mass
Units (AMU); Tune insures that the Mass
Axis is accurately calibrated.
Ratio of Mass Peaks. . . . . . . . . . . . The Mass Calibration status measures and
records the ratio of mass fragments to preset
values. The ratio of the mass peaks controls
the quality of the Mass Spectrum generated
by the HAPSITE.
AutoTune and Manual Tune are performed using a calibration mixture in which the
mass fragments (AMU) and the ratios of the mass fragments are known. The
HAPSITE uses a mixture of two compounds that together contain mass fragments
that span the mass range of interest. The compounds are:
 1,3,5-Tris (trifluoromethyl) benzene
 Bromopentafluorobenzene