Standard Addition Method (Ex-Furnace Addition) - Hitachi ZA3000 Series Instruction Manual

5.1 Various Measurement Methods
5.1.3 Standard
Addition Method
(ex-furnace
addition)
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. (See Fig. 5-2.)
Fig. 5-6 shows the samples to be prepared. Use blank samples
which resemble the unknown samples in terms of acid
concentration, etc. Add to the standard samples (STD) a certain
amount of unknown samples and the standard solution of an
element to be measured after changing the concentration. Then,
mix the entire liquid samples with pure water, etc. You can
create working curves by taking into consideration the co-
existing substances as the STD includes the equal amount of
the unknown samples.
In the ex-furnace addition method, standard-added samples are
to be prepared manually and set in the autosampler for
implementing the standard addition method. (See Fig. 5-6.)
If mixing of unknown and standard samples by in-furnace
addition is inadequate due to a reason such as a high viscosity
of unknown sample, the ex-furnace addition method should be
used.
NOTE: The number of unknown samples is limited to 1 (a
series of standard-added samples) in measurement by
the ex-furnace addition method.
Blank test STD1 STD2
Fig. 5-6 Aliquot Preparation in Standard Addition Method
5 - 8
STD3 STD4
Solvent
Standard
solution
Unknown
sample
Blank
sample