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4.9 Standard Addition Method and Simple Standard Addition
Method
AA-6800/6650 Instruction
The standard addition method is used when there is interference by coexistent material (matrix) in the sample
and its influence is given to the measured value. For the standard addition method, equal volumes of unknown
sample solution are prepared, and a standard solution of different but known concentration is added to each of
the unknown sample solutions. The absorbance is measured for each of these samples, and a calibration curve
is created. The unknown sample concentration is obtained from the point at which the extended calibration
curve intersects with the horizontal axis.
Figure 4.47 Standard Addition Method
When the coexistent material or matrix of plural unknown samples are similar, measure one of them by
standard addition method, and you can use the slope of the same calibration curve to determine the
concentrations of other unknown samples. This is called simple standard addition method.
Figure 4.48 Simple Standard Addition Method
When using these methods, the absorbance of standard addition samples must be within the range that has
linearity of calibration curve. To check whether the result is valid or not, refer to the coefficient of correlation.
4.9 Standard Addition Method and Simple
Standard Addition Method
Absorbance
Standard addition concentration
Concentration of unknown sample
Absorbance
Sample concentration by simple standard addition method
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