Metrohm 746 VA Trace Analyzer User Manual
Page 300
5.6.3 SUBSTANCES
746 VA Trace Analyzer / 747 VA Stand
5-149
Parameter
Range; Default value / Meaning
•
Determining working range
Extrapolations above the range determined with calibration solu-
tions are not allowed. Thus, enter the maximum admissible
working range on the dialog page "SUBSTANCES".
•
Keep temperature constant
Owing to the large temperature dependence of the measured
values (
≥
2%/°C), it is advisable to work with the 6.1418.220 ther-
mostatted measuring vessel.
•
Consideration of blank values
Any blank values must be determined separately and subtracted
in the formula calculation on the dialog page "CALCULATIONS".
Curve type
linear, 0/linear, nonlin, 0/nonlin; linear
Curve type for calibration curve
The calibration curve can be determined with linear or nonlinear
functions:
linear
Straight line of type y = a + bx
Calculation by weighted linear regression.
Minimum number of calibration solutions: 2
0/linear
Straight line of type y = bx
Calculation by weighted linear regression, the line is
passed through the origin.
Minimum number of calibration solutions: 1
nonlin
Curve of type y = a + bx + cx
4
Calculation by weighted curve matching.
Minimum number of calibration solutions: 3
0/nonlin
Curve of type y = bx + cx
4
Calculation by weighted curve matching, the curve is
passed through the origin.
Minimum number of calibration solutions: 2
y:
EV
Evaluation value (A, W or s)
x:
ρ
eff
Effective mass concentration in the
analysis solution (g/L)
a:
Y.offset
Intercept
b:
Slope
Slope of the line or slope of the curve
in the linear region
c:
Nonlin.
Non-linearity factor