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IPN 074-397-P1G
HAPSITE Smart Operating Manual
Chapter 7
Tune
7.1 Introduction to Autotune and Manual Tune
Ensuring the mass spectrometer (MS) performance requires the MS functionality
to be checked at startup and after 8 hours of continuous operation. The process of
verifying the function of the Mass Spectrometer is called Tune. Tune can be
accomplished by either 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 the reference spectrum
from the National Institutes of Standards and Technology (NIST) library to give high
similarity indexes, or with 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/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 accomplished 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 provide mass fragments
across the mass range of interest. The compounds are:
1,3,5-Tris (trifluoromethylbenzene)
Bromopentafluorobenzene.
Proper tuning of the MS insures good quality library matches.
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