Performing A Quantitative Analysis - Agilent Technologies 7500 ICP-MS Operator's Manual

Agilent 7500 ICP-MS ChemStation Operator's Manual

Performing a Quantitative Analysis

Performing a
Quantitative Analysis
Quantitative analysis enables you to determine the concentrations of specific
elements in unknown samples. You run the sample solutions and then calculate
concentrations for the elements of interest by comparing them to calibration plots
for those elements (external calibration). To perform a quantitative analysis you
must first analyze calibration standards and set up a calibration plot for each element
in the calibration solution. ChemStation can then automatically calculate
concentrations in the unknown samples based on the calibration plots.
Normally, internal standards are added to both calibration standards and samples to
normalize instrument response. Typically 1-3 internal standard elements are used.
Internal standards compensate for changes in instrument sensitivity that occur if the
sample matrix is different from the calibration standard matrix (normally HNO ),
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and for any drift in sensitivity.
ChemStation can also quantitate using standard addition, where several aliquots of
the unknown sample are spiked with calibration standards. The calibration plot is
determined in the sample matrix itself. Standard addition can lead to improved
accuracy in unknown matrices, but is more time consuming.
This chapter explains how to run calibration standards, set up and use calibration
plots, alter calibration plots by removing individual points, subtract blank data files
from sample data files, and generate quantitative reports.
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