Finding The Best Signal Amplification - Agilent Technologies 1100 Series Reference Manual

optical bandwidth (FLD=20 nm) which cause a systematic wavelength maximum shift
depending on the absorbance spectrum of the compound under evaluation.

Finding the Best Signal Amplification

Increasing the PMTGAIN increases the signal and the noise. Up to a certain factor the
increase in signal is higher than the increase in noise.
The step from gain to gain is equal to a factor of 2 (which is the same as on the HP
1046 A FLD ).
In
Agilent Technologies isocratic sample which was diluted 1000 times). With increasing
PMTGAIN there was an improvement in signal-to-noise up to 10. Above 10 the noise
increased proportionately to the signal with no improvement in signal-to-noise.
PMT
11
10
9
8
6
4
Figure 27
The reason for this is the fact, that quantification of baselines (especially at low
background levels) is not sufficient for statistically working filter methods. For the best
gain, check your solvent under flow conditions with the auto-gain function. Do not use
higher values than proposed by the system, if not necessary, because of excessive high
fluorescence signals.
1100 Series FD Reference Manual 65
Figure 27 the PMTGAIN was gradually raised from 4 up to 11 (the peak is from the
Finding Best PMTGAIN for Biphenyl
Optimizing the Fluorescence Detector 3