Optimizing Spectral Acquisition (Dad Only) - Agilent Technologies 1220 Infinity II LC User Manual

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Detector Description
Agilent 1220 Infinity II LC Diode Array Detector (DAD)
Substances with fine structures and steep slopes like benzene are very rare.
In most cases the width of absorbance bands in the spectrum is more like
30 nm as with anisic acid (Figure 38 on page 125).
In most situations, a slit width of 4 nm will give the best results.
Use a narrow slit (1 or 2 nm) if you want to identify compounds with fine
spectral structures or if you need to quantify at high concentrations
(> 1000 mAU) with a wavelength at the slope of the spectrum. Signals with a
wide bandwidth can be used to reduce baseline noise. Because (digital)
bandwidth is computed as average of absorbance, there is no impact on
linearity.
Use a wide (8 or 16 nm) slit when your sample contains very small
concentrations. Always use signals with bandwidth at least as wide as the slit
width.

Optimizing Spectral Acquisition (DAD only)

Storage of all spectra consumes a lot of disk space. It is very useful to have all
spectra available during optimization of a method or when analyzing unique
samples. However when running many samples of the same type, the large size
of data files with all spectra may become a burden. The detector provides
functions to reduce the amount of data, yet retaining the relevant spectral
information.
For spectra options see Table 23 on page 134.
Range
Only the wavelength range where the compounds in your sample absorb
contains information that is useful for purity checks and library searches.
Reducing the spectrum storage range saves disk space.
Step
Most substances have broad absorbance bands. Display of spectra, peak purity
and library search works best if a spectrum contains 5 to 10 data points per
width of the absorbance bands. For anisic acid (the example used before) a
1220 Infinity II LC System User Manual 129