Metrohm 746 VA Trace Analyzer - Manual (Page 495)

6 Data processing and evaluation
746 VA Trace Analyzer / 747 VA Stand
6-32
Ref.subst Name of reference substance
V0.CSoln.
Addition volume of the calibration solutions
CSoln.name Name of the calibration solutions
Mass conc. Mass concentration ρ
aa
of the calibration solutions
Soln.name
Name of the solution with the internal standard
(for Mode = referen. , must be identical with the name
specified in the RADD instruction)
Mass conc. Mass concentration ρ
rr
of the solution with the internal stan-
dard (for
Mode = referen.
)
In the content determination using an internal standard, the following procedure is
used to calculate the sought mass concentration ρ
eff,s eff,s
of the sample (see also ex-
ample in section 4.4):
1 Measurement of the calibration solutions
The calibration solutions of known mass concentration
ρ
a,n a,n
and ρ
r,n r,n
are each
measured several times. This gives:
EV
n
Evaluation quantity for n th calibration solution
(for analyte and reference substance)
EV
n
.mean Mean value of the evaluation quantities for n th calibra-
tion solution (for analyte and reference substance)
Std.dev. Standard deviation of the n th individual value EV
n
(for measurement and reference substance)
EV
a,n
/ EV
r,n
Ratio of the evaluation quantities for n th calibration
solution
ρ
eff,a,n eff,a,n
Effective mass concentrations of the analyte for the
calibration solutions (calculated from ρ
a,n a,n
taking the
dilution into account)
ρ
eff,r,n eff,r,n
Effective mass concentration of the reference sub-
stance for the calibration solutions (calculated from
ρ
r,n r,n
taking the dilution into account)
ρ
eff,a,n eff,a,n
/ ρ
eff,r,n eff,r,n
Ratio of the effective mass concentrations of analyte
and reference substance for n th calibration solution
2 Determination of the calibration curve
The calibration curve is determined using a linear function of type
0/linear :
y = bx Straight line through zero point
The parameter b is determined by the procedure described in section 6.9.3
with y =
EV
a
/
EV
r
and x = ρ
eff,a eff,a
/ ρ
eff,r eff,r
by weighted least squares minimization.
This parameter is displayed on the "RESULTS/Calibrations" page and has
the following meaning:
b Prop.factor Proportionality factor (slope of the calibration curve)