Peak Detection - Slope Threshold - PerkinElmer LabChip GX User Manual

Because peaks tend to broaden as time progresses, use a short
filter width initially and then switch to a wider filter near the end of
the signal for this type of signal. The High Size filter on the
Find Tab
affecting the earlier peaks. Ultimately, some noise may have to be
tolerated to avoid distorting the peak shape.

Peak Detection - Slope Threshold

Peak baseline and Peak detection are controlled primarily through
the Slope Threshold property on the
slope increases rapidly at the start of the peak, becomes negative
after crossing the peak apex, and then returns to a small value at
the end of the peak. The slope threshold is the slope value used to
identify the start and end of the peak. The regions outside the zone
where the absolute value of the slope exceeds the slope threshold
are deemed baseline.
The slope threshold determines the peak start point and end point:
•
•
A baseline is drawn under each peak region using a signal average
in the baseline regions on each side of the peak.
V4.2
can be used to smooth the tail of the upper marker without
Figure 47. High Size Filtering
The first point with local derivative above the slope threshold
indicates the Start Point of a peak.
The first point where the negative slope on the falling edge of
the peak drops below the slope threshold indicates the End
Point of a peak.
LabChip GX User Manual
Understanding Peak Finding 109
Peak Find Tab. The signal
PerkinElmer
Peak