COMMITTEEDRAFT
ISO/CD 15151 | IDF 229
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13
used to improve the precision of the analysis. In this way also some of the variables in the excitation and
processingof spectra canbeminimizedor eliminated by adopting the internal standard technique.
If the linearity is guaranteed, two calibration solutions shouldbe enough to set up the calibration curve.
Nevertheless, three to five calibration solutions are recommended. In all cases the linearity should be checked
on a regular basis. The working area should be chosen in such a way that the concentration of the sample
solution is situated in themiddle of the calibration curve.
B.3.3 Internal standard
If an internal standard is used in line than it will correct for the drift in the signal. The test portion needs an
exact dilution.
If the internal standard is added to the test portion, than it will correct either for the drift in the signal and the
dilution.
B.3.4 Standard addition
Standard addition is a way of checking measurement of concentrations for samples with highly variable
solution components. The standard additionmethod is also used to compensate for chemical and othermatrix
interferences and effects. Standard addition is also a way in checking completeness of dry ashing or
destruction.
The standard addition is a small volume of known concentration (e.g. calibration solution flask number 3
(9.3.2.1)).
The recovery should be between90 and 100%.
MTE-03
FORWORKINGGROUP/ERPUSEONLY
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