Thermo Scientific Thermo Scientific Vanquish VC-D40, Operating Manual

Page: 86 / 174

6 • Operation
Page 86 Variable Wavelength Detectors (VC-D40, VF-D40)
Operating Manual
6.6 Operational Modes of the Device
6.6.1 Single-Channel Mode
Single-channel mode is the default mode of operation for the detector.
As this mode provides the highest possible data rates and best signal-to-
noise ratio, always use the single-channel mode for routine operation of
the detector.
Consider the following for operating the detector in single-channel
mode:
• Sample components should absorb strongly at the selected
wavelength. Therefore, select a wavelength on an absorption
maximum.
• At the selected wavelength no other sample components should
absorb that can falsify the peaks of the sample components of
interest.
• If the absorbance spectra of the sample components differ
significantly, the measurement wavelength can be switched any
time and as often as required during an acquisition.
• The switching is considerably shorter than one second and should be
performed when no sample components of interest are present in
the flow cell.
While the wavelength is switched, no absorption measurement
takes place for a short period of time. If the wavelength is switched
during an analysis of a sample component, the peak area changes,
and a correct quantification is not possible. You can choose between
three different baseline behaviors, when switching the wavelength
(for details, see
Baseline Behavior ( } page 93) ).
6.6.2 Multi-Channel Mode
The detector provides a multi-channel mode that offers additional
operation functions for method development and peak-purity analyses.
In multi-channel mode, data can be recorded on more than one channel
simultaneously with different, selectable wavelengths. The detector
quickly switches between the selected wavelengths. The maximum
number of channels depends on your detector variant.
A single analysis is sufficient to measure several channels. Sample
components with different absorption characteristics can be analyzed
even without complete chromatographic resolution.