Selecting The Wavelength; Bandwidth; Fig. 28 Comparison With And Without Reference Wavelength - Knauer Azura DAD 2.1L Benutzerhandbuch

38 Optimizing the Detector

Selecting the Wavelength

Signal wavelength Wavelength selection can influence the sensitivity, selectivity
and linearity of a measurement. The best wavelength for a given
measurement (signal wavelength) is that which gives the maxi-
mum absorbtion above the UV cutoff of the mobile phase. In
cases where there are multiple components with different absor-
bance maxima, a compromise wavelength must be chosen
where all components absorb.
Reference wavelength In order to minimize baseline drift due to refractive index effects,
a reference wavelength can be set (see figure 28). The reference
should be set in the same spectral region as the signal wave-
length (UV or VIS) but at a wavelength at which the analyte has
no absorbance.
Default reference wave- By default, the reference wavelength 360 nm is activated (see
length "Re-Setting the Device" on page 34). This is a suitable value for
most applications.
Fig. 28 Comparison with and without reference wavelength
When selecting the signal and reference wavelengths, the
respective bandwidths must also be selected (see the following
section).

Bandwidth

The bandwidth defines the total number of wavelengths actually
registered by the photodiode when a specific wavelength is set.
KNAUER DAD 6.1L, DAD 2.1L, MWD 2.1L User Manual V6700, Version 1.0