Metrohm 746 VA Trace Analyzer User Manual
Page 284
5.6.3 SUBSTANCES
746 VA Trace Analyzer / 747 VA Stand
5-133
Parameter
Range; Default value / Meaning
t.threshold
0.100...9.99 ms; 4.0 ms
Time limit value
Minimum time limit (peak area) for the assignment of a peak to a
substance (for measurement mode PSAMODE). With the aid of the 1
st
derivative of the peak curve, the difference
∆
minmax
is multiplied by the
empirical factor f
MM
valid for the PSAMODE to determine the esti-
mated peak area
approx.peak
. This estimated value must be larger
than
t.threshold
for the substance to be recognized (see also
section 6.6).
With non-gaussian shaped peaks, the peak height
approx.
peak
estimated from the derivative can differ greatly from
the actual peak height
t.peak
. It may be necessary to
modify
t.threshold
for the results to be displayed or
suppressed in the desired manner.
aU.width
U.width min
U.width max
U.verify ± U.tol
aU.peak
approx.peak =
aU.max
aU.min
d(t/U)/dU
U
U
t/U
The substance recognition is
based on the recognition
parameters specified for the
individual substances. The
following conditions must be
met for a detected peak to
be assigned to a substance:
1.
aU.peak =
U.verify
±± U.tol
2.
aU.width > U.width min
aU.width < U.width max
3.
approx.peak >
t.threshold
∆
minmax
×
f
MM
∆
minmax
estimated
gaussian
peak