1260 Infinity Binary LC - System User Guide 127
Appendix
6
Setting Up a Method using Edit Entire Method
• Advanced - Analog Output
The 1260 Infinity DAD 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.
• Advanced - Margin for Negative Absorbance
The default setting is 100 mAU, which means 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.
• Advanced - Autobalancesets the absorbance level to zero at all wavelengths
(that is, balances all points on the spectrum to zero) and hence also
zeroes the baseline signal. Prerun is selected to balance just before the
start of the run, which is the normal situation. Sometimes Postrun is
alternatively selected to balance at the end of the run after the postrun
time has expired. For example, if the signal always shows a negative
drift and the user prefers the run to end at zero absorbance, then this
will set the correct zero level for the following run. It will not
retrospectively change the run at the end of which it performed the
balance.
• Advanced - Lamps on required for acquisition: the 1260 Infinity DAD has one
UV lamp and it needs to be on for analysis so this box should be
checked.
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