Optimization Overview - Agilent Technologies 1260 Infinity User Manual

5
Optimizing the Detector

Optimization Overview

Optimization Overview

1 Setting the right PMT value
If you have changed one or more parameter(s), you have to press 'OK' to write down the
N O T E
new settings into the FLD. Then re-enter 'FLD-Signals' and start the PMT gain test.
2 Using an appropriate response time
3 Finding the optimum wavelength
104
For most applications a setting of 10 is adequate (see
Signal Amplification"
linear range making PMT switching unnecessary for most applications. For
example, if at high concentrations a peak is cut off; decrease the PMT
setting. Remember that low PMT settings decrease the signal to noise ratio.
The built-in PMT gain test uses the parameters in the detector. When using
the PMT gain test, the wavelength setting and lamp energy mode
(depending on Multiwavelength-Mode and Lamp-Economy) will affect the
PMT gain calculation.
For most applications a setting of 4 seconds is adequate (see
Best Response Time"
columns at high flow rates) a lower setting is recommended. Bear in mind
that even if the response time is too high fast peaks will appear a little
smaller and broader but retention time and peak areas are still correct and
reproducible.
Most fluorescent active molecules absorb at 230 nm (see
Wavelengths" on page 107). Set the excitation wavelength to 230 nm and
on-line scan the emission spectra (multi-emission mode). Then set the
determined emission wavelength and perform a multi-excitation scan
(multi-excitation mode) to find the best excitation wavelength.
on page 109). The FLD A/D converter exhibits a large
on page 117). Only for high speed analyses (short
"Finding the Best
"Selecting the
"Finding the Best
Agilent 1260 FLD User Manual