Agilent Technologies 1100 Series Reference Manual page 37

400 nm, this signal will show you virtually every compound which can be detected by
UV absorbance.
Many compounds show absorbance bands in the spectrum.
spectrum of anisic acid as an example.
To optimize for lowest possible detectable concentrations of anisic acid, set the sample
wavelength to the peak of the absorbance band (that is, 252 nm) and the sample
bandwidth to the width of the absorbance band (that is, 30 nm). A reference of 360,100
is adequate. Anisic acid does not absorb in this range.
If you work with high concentrations, you may get better linearity above 1.5 AU by
setting the sample wavelength to a valley in the spectrum, like 225 nm for anisic
acid.
Figure 10
A wide bandwidth has the advantage of reducing noise by averaging over a wavelength
range — compared to a 4 nm bandwidth, the baseline noise is reduced by a factor of
approximately 2.5, whereas the signal is about 75 % of a 4-nm wide band. The signal-
to-noise ratio for a 30 nm bandwidth is twice that for a 4-nm bandwidth in our example.
1100 Series DAD and MWD Reference Manual
sample wavelength 252 nm
30 nm
bandwidth
Wavelength (nm)
Optimization of Wavelength Setting
37
How to optmize the Detector
Figure 10
Anisic acid
Reference bandwidth 100 nm
Reference wavelength 360
2
shows the