Waters 2475, Operator'S Manual, Page: 112 / 228

3-40 Using the Detector
Setting gain and EUFS
Choosing a gain setting for the PMT before injecting sample is a necessary
part of fluorescence measurement with detectors that use PMTs. For the best
signal-to-noise ratio, set a gain that maximizes the dynamic range of the
electronics (see page 1-17 ). A gain that is too high overloads the pre-amplifier,
and a value of –9999.9 appears in the Emission/Energy units field.
Gain set too high (fluorescence pinned to –9999.9 EU)
Gain set too high alarm message
The value of -9999.9 EU in the Emission/Energy Units field and the alarm
help differentiate between too high a gain setting and too low an EUFS
setting. When the EUFS is set too low, flat-topped peaks appear, because the
upper limit of the output range is exceeded.
Tip:
An EUFS over-range situation occurs only when you use the analog
outputs.
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