Agilent Technologies 1290 Infinity LC System System Manual And Quick Reference page 130

6
Appendix
Setting Up a Method using Edit Entire Method
• Advanced - Analog Output
• Advanced - Margin for Negative Absorbance
• Advanced - Slit
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• Store controls the spectral collection mode with the following options:
None – no spectra stored,
Apex+Baselines – 3 spectra taken at start, apex and end of peak,
Apex+Slopes+Baselines – 5 spectra taken at start, upslope, apex,
downslope and end of peak,
All in Peak – all the available spectra within a peak are stored,
All – all spectra throughout the run are stored,
Every 2nd Spectrum – stores only alternate spectra acquired throughout
the run.
• Range – Spectra can be saved across the full range of the detector, 190 nm
to 640 nm, or any reduced range chosen as appropriate by the user. (This
also reduces the number of data to be stored).
• Step – controls the interval (nm) of the data stored in a spectrum and
hence affects the spectral resolution seen. The default setting of 2 nm is a
good choice for most applications.
• Threshold – determines that spectra are not stored for peak heights below
this value (mAU).
The 1290 Infinity detector has one analog signal output connector for use
with data systems that do not accept a digital input. The following may be
set:
• Zero Offset places the zero level at a set percentage of the output signal
hence allowing some scope for negative drift,
• Attenuation scales the set absorbance to the full output.
The default setting is 100 mAU, which means that the detector has
sufficient dynamic range, considering where the zero level was set, to
measure down to this value. To measure larger negative peaks or follow a
baseline with a strong negative drift, the value needs to be adjusted
downwards to prevent the signal flat-lining at the bottom of the range.
However, it should not be changed without good reason, as making it more
negative will increase baseline noise and reduce the range available for
measuring positive peaks.
Agilent 1290 Infinity LC System Manual and Quick Reference