Metrohm 746 VA Trace Analyzer - Manual (Page 483)

6 Data processing and evaluation
746 VA Trace Analyzer / 747 VA Stand
6-20
6.9 Content calculation
6.9.1 General
With polarographic and voltammetric methods, the measured evaluation quantities
EV: (wave height, peak height or peak area, see section 6.8) for a sub-
stance are proportional to its mass concentration ρ
subst subst
:
EV: = ƒƒ ( ρ
subst subst
)
The relation between evaluation quantity and mass concentration must be deter-
mined by a calibration with reference solutions. The 746 VA Trace Analyzer offers
the following three techniques for this:
• Standard addition (see section 6.9.4)
Content determination using single or multiple addition of a standard
solution
• Calibration curve (see section 6.9.5)
Content determination using a calibration curve previously determined
with reference solutions
• Internal standard (see section 6.9.6)
Content determination by addition of a reference substance using the
proportionality factor determined previously with reference solutions
The goal of all three calibration methods is to calculate the mass concentration ρ
ss
of
the sample referred to the added sample volume V.sample , which is then put out
on the dialog page "RESULTS/Evaluations" and in Report Full as Mass conc. =
MC: :
ρ
ss
= =
ρ
ss
Mass concentration of the sample
(=
Mass conc. on the "RESULTS/Evaluations" page)
m.sample Substance mass in the sample
V.sample Sample volume (addition volume for SMPL instruction), dependent on
the entry of the sample size (see section 5.4.4):
V.sample = S0 (undiluted, S0 in L)
V.sample = S0/S2 (undiluted, S0 in g)
V.sample = V.fraction (diluted , S0 in L or g)
m0.sample Substance mass in the measuring vessel
(=
Mass on the "RESULTS/Evaluations" page):
m0.sample = m.sample * f
AS AS
V0.sample Sample volume in the measuring vessel
(displayed on the "RESULTS/Evaluations" page):
V0.sample = V.sample * f
AS AS
The automatically calculated dilution factor ff
AS AS
takes into account all
dilutions of the sample volume on the 695 Autosampler before addi-
tion to the measuring vessel:
f
AS AS
= 1 no dilution on the Autosampler
f
AS AS
< 1 dilution on the Autosampler
m.sample
V.sample m0.sample
V0.sample