ThermoFisher Scientific Vanquish VC-D50, Руководство по эксплуатации

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6 • Operation
Fluorescence Detectors (VC-D50, VC-D51, VF-D50, VF-D51)
Operating Manual Page 109
• If the selected sensitivity is too large , the PMT signal is saturated. In
this case, the detector automatically reduces the sensitivity. Markers
appear in the chromatogram at the beginning and at the end of the
saturation (see figure,
Sensitivity = 8 ). If the detector is not saturated
any more, the Sensitivity setting before saturation is restored.
TIP When the sensitivity was automatically reduced or when the initial
value was restored, the Chromeleon Audit Trail shows a warning with
the new sensitivity value after the adjustment.
Figure 33: Effects of the Sensitivity setting
With Vanquish fluorescence detectors, the intensity of the emission light
(measured by the PMT) is normalized with the intensity of excitation
light through the sample (measured by the reference sensor). Therefore,
the values (counts) that the emission channel displays cannot be used
for optimizing the sensitivity. In the figure, the PMT is saturated at
63 million counts. However, under different measuring conditions, the
PMT may be saturated at a value of 100 million counts, for example.
Therefore, use the MaxPMTSaturation parameter to optimize the
sensitivity for each peak as described below. This parameter
continuously records the maximum PMT saturation since the last
ClearMaxPMTSaturation command. The result is reported in percent of
the maximum permitted PMT saturation.