Hitachi ZA3000 Series, Instruction Manual

Page: 333 / 522

5.1 Various Measurement Methods
5 - 4
(4) Specify values in the numeric entry boxes [UNK Replicate]
and [UNK Decimal Place].
(5) Specify values in [Sample Table] and [Autosampler].
(6) If necessary, specify values in [Report Format].
(7) After confirming the conditions specified in the above steps,
carry out measurement.
In the standard addition method, quantitative analysis is
performed while making correction for a possible difference in
sensitivity between standard and unknown samples (mainly due
to chemical or physical interference). In principle, a linear
relation expression regarding concentration (added
concentration) and absorbance of an unknown sample is
determined, and extrapolation is performed on the assumption
that the linear relation is held through the concentration range to
0.
Develop a working curve by adding to a certain amount of
unknown samples a standard solution of a desired element after
modifying the concentration. This working curve is affected by
co-existing substances included in the unknown samples (Fig. 5-
2).
Fig. 5-2 Working Curve in Standard Addition Method
5.1.2 Standard
Addition Method
(in-furnace
addition)
A
x+2
A
x+1
A
x
-C
x
0 C
1
C
2
Absorbance of
unknown sample
Concentration
C1: Standard addition temperature for unknown
sample (1)
C2: Standard addition temperature for unknown
sample (2)
Ax: Absorbance of unknown sample
Ax+1: Absorbance of unknown C1
Ax+2: Absorbance of unknown C2
x: Reciprocal number of unknown sample’s
concentration
Absorbance