Consort C832 Anleitung Seite 15

Standard addition:
The standard addition method is used when the samples can be kept at the same
temperature and a standard of 5 to 100 times the expected sample concentration
is available. The most suitable increment can be found from: increment percent-
age > 100 x expected sample value / standard value.
1. Press MODE until the display shows [Dir.CONC1], [Std.Add1], [Std.Sub1],
[Anl.Add1] or [Anl.Sub1] and choose [Std.Add1]. Press MODE to proceed.
2. The display shows one of the possible increments (1, 2, 5, 10, or 20 %), e.g.
[10% Incr]. Select the desired value and press CAL.
3. Prepare a standard solution of the measured species. Its value should be 5 to
100 times higher than the expected sample concentration. The display shows
one of the possible standards e.g. [Std 1.-3]. Select the desired value and
press CAL.
4. After rinsing the electrodes with distilled water, immerse them in e.g.
100 ml sample solution. The display will show the electrode potential e.g.
[E=307.6]. When readings are stable press CAL.
5. Add a small increment corresponding to the chosen mode (e.g. 10 ml). The
display will show the difference in electrode potential e.g. [dE=48.1]. When
readings are stable press CAL. The instrument calculates the result and shows
the concentration of the sample in the same unit as the standard used for the
addition.
6. For a next measurement press CAL and the same procedure starts again from
point 4). Press MODE to abort.
Standard subtraction:
The standard subtraction method is used to measure species for which stable
standards or ion selective electrodes do not exist. The procedure is similar to
the standard addition method. The most suitable increment can be found from:
increment percentage > 100 x expected sample value / standard value.
1. Calculate the stoichiometric ratio (n) of the reaction: xS + yR > SxRy n=x/y (S
= sample, R = reagent).
2. Press MODE until the display shows [Dir.CONC1], [Std.Add1], [Std.Sub1],
[Anl.Add1] or [Anl.Sub1] and choose [Std.Sub1]. Press MODE to proceed.
3. The display shows one of the possible increments (1, 2, 5, 10, or 20 %), e.g.
[10% Incr]. Select the desired value and press CAL.
4. Prepare a standard solution of the measured species. Its value should be 5 to
100 times higher than the expected sample concentration. The display shows
one of the possible standards e.g. [Std 1.-5]. Select the desired value and
press CAL.
5. After rinsing the electrodes with distilled water, immerse them in e.g.
100 ml sample solution. The display will show the electrode potential e.g.
[E=178.2]. When readings are stable press CAL.
6. Add a small increment corresponding to the chosen mode (e.g. 5
ml). The display will show the difference in electrode potential e.g.
[dE= 34.4]. When readings are stable press CAL. The instrument calculates
the result and shows the concentration of the sample in the same unit as the
standard used for the addition.
7. Calculate the real concentration by multiplying the result with the stoichio-
metric ratio (n). For a next measurement press CAL and the same procedure
starts again from point 5). Press MODE to abort.
C831 • C832 • C833 • C835 • C838
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