Metrohm tiamo 2.2 (ProcessLab) - Manual (Page 1058)

5.6 Commands ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
1042 ￭￭￭￭￭￭￭￭ tiamo 2.2 (ProcessLab)
￭ 3 and multiple point calibration
With at least 3 calibration solutions the calibration function is determined
according to the method of least squares. The sought calibration param-
eters s, E(0) and c
B
are calculated iteratively. If the value for c
B
is lower
than aprox. 0.2 % of the lowest concentration, it is set equal to zero. In
such a case a linear relation between U
i
and log(c
i
) results.
The variance Var is calculated and output in any case with at least 4
calibration standards. If c
B
= 0, the variance is even calculated for 3
standards.
U
i
: measured potential
U
i,c
: potential calculated out of the calibration curve
n : number of measuring points
F : degrees of freedom (2 for c
B
= 0, 3 for c
B
≠ 0)
Command variables
The following command variables are generated in the method run by the
command CAL LOOP Conc and can be used in formulas under the desig-
nation 'Command name.Variable designation':
Identifi-
cation Description
.BLV Blank value calculated from the calibration
.BSY Command status; 1 = BUSY, HOLD or ERROR; 0 =
READY; invalid (variable not available) = Command has
never been started
.ENP Electrode zero point calculated from the calibration
.FIN Command status; 1 = Command has ended at least
once, 0, invalid (variable not available) = Command has
never ended
.LCO Loop counter = current quantity of completed runs, both of
Repeat loops and of While loops
.LST Start time of the loop command (Date/Time)
.SLO Electrode slope calculated from the calibration