Technical data

216 Understanding Your Agilent ChemStation
10 Using the ChemStation Reports
Reporting Results
calibration and unknown samples must be known accurately. The reliability of
the external standard report is limited by the reproducibility of the injection
and any other factors that might change from sample to sample.
Internal Standard Report
The limitations of the external standard procedure can be overcome by using
the internal standard approach. An accurately known amount (not necessarily
the same amount) of the internal standard is added to both the calibration
sample(s) and unknown sample. The response of each compound of interest is
divided by the response of the internal standard to give a response ratio. The
calibration curves are a plot of this response ratio versus the amount ratio and
this information is used in the calculation of the reported results. In this way
inadvertent errors in injection volume or slight changes in the
chromatographic/electropherographic system that affect all compounds
similarly are cancelled out. The ISTD report lists the results with units of your
choice.
Control Charts Report
The Control Charts Report tracks a single result from multiple runs for a
specific calibrated compound. The Control Chart feature is installed after the
ChemStation is operational. Methods that use this feature pass the tracked
result to a Microsoft Excel work sheet after each run. Excel is then used to
print the report.