Agilent Technologies 1290 Infinity LC System System Manual And Quick Reference page 60

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Optimization of the Agilent 1290 Infinity LC System
How to Achieve Higher Sensitivity
How to Achieve Higher Sensitivity for Detector
The detector has a number of parameters that are used to optimize
performance. The following sections describe how the detector parameters
affect performance characteristics:
• Flow cell affects sensitivity,
• Wavelength and bandwidth affect sensitivity, selectivity and linearity,
• Slit Width affects sensitivity, spectral resolution and linearity,
• Peak Width affects sensitivity and resolution.
Flow Cell
The Max-Light cartridge flow cell has a standard 10 mm path length and is
optimized for minimal volume and dispersion ( volume 1.0 µl). It has high
light transmission minimizing noise to reduce noise due to the optofluidic
waveguide. It is suitable for use with a wide range of analytical columns from
short narrow-bore columns to long standard diameter (4.6 mm) columns.
Generally the peak dispersion volume (calculated from peak width x flow rate)
should be greater than about 2 µl for this cell (for example 0.02 min x
200 µl/min = 4 µl).
The Max-Light high sensitivity cell has a path length of 60 mm and this will
give between three and five times increase in signal-to-noise values depending
on the application conditions. The dispersion volume is fractionally increased
compared to the standard cell.
Wavelength and Bandwidth
The detector measures absorbance simultaneously at wavelengths from
190 nm to 640 nm using diode-array detection. A UV-lamp provides good
sensitivity over the whole wavelength range. The diode-array detector (DAD)
can simultaneously compute and send to the data system up to eight
chromatographic signals and the full-range spectra at every time point. A
multi-wavelength detector (MWD) processes only the chromatographic signals.
A UV chromatogram or signal is a plot of absorbance data versus time and is
defined by its wavelength and bandwidth.
• The wavelength indicates the center of the detection band.
• The bandwidth defines the wavelength range over which the absorbance
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values are averaged to give the result at each time point.
Agilent 1290 Infinity LC System Manual and Quick Reference