Metrohm 761 Compact IC - Manual (Page 119)

4.4 Methods
761 Compact IC
109
4.4.4 Integration
761 COMPACT IC / Method / Integration
This menu item opens the Integration parameters window which contains
parameters and events for peak integration and consists of the follow-
ing two tabs:
Setup Integration parameters.
Events Integration events.
The «Compact IC 761» software includes a built-in automatic integra-
tion algorithm to detect peaks on the chromatographic curve and to
evaluate them using calculated baselines. The integration procedure is
tuned by the integration parameters on the Setup tab and the integration
events on the Events tab. Integration events have higher priority than in-
tegration parameters. The integration can be modified manually using
the peak editor (see section 4.5.4).
The built-in integrator algorithm is based on the use of the first deriva-
tive (slope). In order to decide whether the slope at some point is sig-
nificant, the first derivative value is divided by the baseline noise and
the result is compared with a threshold value called “ Slope ”. The
threshold values for the upslope and downslope differ.
The baseline and the starting and finishing points are determined for
each peak. For separated peaks the baseline consists of a straight line
between the starting point and the finishing point. For neighboring
peaks which overlap a common baseline is normally constructed; this
connects the starting point of the first peak with the finishing point of the
last peak. The peaks are separated from one another by dropping a
perpendicular line from the lowest point (valley) between the peaks to
the common baseline. Alternatively the baseline can also be drawn di-
rectly between the valleys of the peaks with the event Enable valley-to-
valley (see integration events for baseline).
Single
peak
Peak apex
Merged peaks
Drop line Valley point Baseline Peak end Peak start