411829-L, Collection and Fractionation April 2012 Page A-10
A
A.3.5 Shoulder Slope Fractionation
A.4 Auto Extend of Gradient
When the system enters the Auto-Extend mode, the gradient is extended with an isocratic segment
that is 25% of the total gradient length using the end solvent mix of the current gradient. The
criteria for deciding if the gradient should be extended depend on the collection method and the
parameters defined for the collection method:
* Auto extend can be enabled or disabled in the system mode. The predefined system settings for auto
extend are: Threshold = 100 mAU and Slope = 180 mAU/CV.
If the method in use is a combination of two or more of the methods above, the gradient is extended
if one or more of the methods’ criteria are meet. If a dual variable or UV-VIS detector is used with
the UV1+UV2 detection mode, both detector signals used for collection and fractionation are
checked for a possible auto extend of the gradient.
Collection Method Auto-Extend Criteria
Manual If the current calculated slope and/or absorption level is greater than the predefined
system settings for auto extend, the gradient is extended.*
Collect All If the current calculated slope and/or absorption level is greater than the predefined
system settings for auto extend, the gradient is extended.*
Threshold If the current absorption level is greater than the threshold defined in the method
and/or the current calculated slope is greater than the predefined slope for auto
extend*, the gradient is extended.
Slope If the system is collecting, the current calculated slope is greater than the slope
defined in the method, and/or the current absorption level is above the predefined
threshold for auto extend*, the gradient is extended.
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