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5 Calibration
case, is a graph wherein on the Y -axis the ratio of the value of the analyte signal to
internal standard signal is mapped and on the X-axis the mass or concentration of
the analyte is mapped. As previously mentioned, an internal standard may be added
to the sample or may already be present in the sample.
Assuming the influence of various instrumental and experimental parameters on
the analytical signal obtained, the ideal calibration should meet the following conditions:
– An identical chemical environment of the analyte in the samples used for the
calibration and in the sample;
– The same procedure for the preparation of calibration solution and the sample;
– Identical measurement conditions for calibration solutions and samples.
Thus, the method of the internal standard approximate to the best extent the
calibration conditions to the above-mentioned requirements.
In the method of the internal standard, the analytical signal—defined as the ratio
of the signal obtained for an analyte that of internal standard—eliminates the influences that affect in the same or similar manner the signals of both substances. The
principle of the internal standard method is that a fixed amount of internal standard
is added to all solutions/samples and the analytical signal is proportional to the analyte in the sample. The internal standard method allows the influence resulting from
changes in concentration of the analyte at the time of preparation procedure (incomplete extraction, change of the volume) to be reduced; eliminates the influence of
some interferences related to the composition of the sample (e.g., spectral interference); and reduces the influence of measurement conditions on the analytical signal
(measurement of the signal for internal standard and the analyte in the same measurement cycle). It is worth noting that the internal standard method is very useful
in measuring techniques, in which it is possible to obtain signals for more than one
component of the samples in one measurement cycle.
– Internal standard should exhibit similar physicochemical properties as the
analyte;
– Internal standard should not interact with both the analyte and other component of the sample.
5.7 Internal Standardization
In some analytical cases, knowledge of the relative contents of the sample components is important. If so, the content of all detected components are normalized to
100% or to 1; thus the content of the individual component is expressed as a percentage or fraction. The method of internal standardization is used in those cases where
5 Calibration
case, is a graph wherein on the Y -axis the ratio of the value of the analyte signal to
internal standard signal is mapped and on the X-axis the mass or concentration of
the analyte is mapped. As previously mentioned, an internal standard may be added
to the sample or may already be present in the sample.
Assuming the influence of various instrumental and experimental parameters on
the analytical signal obtained, the ideal calibration should meet the following conditions:
– An identical chemical environment of the analyte in the samples used for the
calibration and in the sample;
– The same procedure for the preparation of calibration solution and the sample;
– Identical measurement conditions for calibration solutions and samples.
Thus, the method of the internal standard approximate to the best extent the
calibration conditions to the above-mentioned requirements.
In the method of the internal standard, the analytical signal—defined as the ratio
of the signal obtained for an analyte that of internal standard—eliminates the influences that affect in the same or similar manner the signals of both substances. The
principle of the internal standard method is that a fixed amount of internal standard
is added to all solutions/samples and the analytical signal is proportional to the analyte in the sample. The internal standard method allows the influence resulting from
changes in concentration of the analyte at the time of preparation procedure (incomplete extraction, change of the volume) to be reduced; eliminates the influence of
some interferences related to the composition of the sample (e.g., spectral interference); and reduces the influence of measurement conditions on the analytical signal
(measurement of the signal for internal standard and the analyte in the same measurement cycle). It is worth noting that the internal standard method is very useful
in measuring techniques, in which it is possible to obtain signals for more than one
component of the samples in one measurement cycle.
– Internal standard should exhibit similar physicochemical properties as the
analyte;
– Internal standard should not interact with both the analyte and other component of the sample.
5.7 Internal Standardization
In some analytical cases, knowledge of the relative contents of the sample components is important. If so, the content of all detected components are normalized to
100% or to 1; thus the content of the individual component is expressed as a percentage or fraction. The method of internal standardization is used in those cases where