Doc. 031851-05 12/04 1-1
1 • Introduction
1.1 Introduction to Ion Chromatography (IC)
NOTE Appendix E contains a glossary of chromatography
terms.
The Dionex ICS-90 Ion Chromatography System (ICS-90) performs isocratic ion
analyses using suppressed conductivity detection. An ion chromatography system
typically consists of a liquid eluent, a high-pressure pump, a sample injector, a
separator column, a chemical suppressor, and a conductivity cell. Before running
a sample, the ICS-90 is calibrated using a standard solution. By comparing the
data obtained from a sample to that obtained from the standard, sample ions can
be identified and quantitated. A computer running chromatography software
automatically converts each peak in a chromatogram to a sample concentration
and produces a tabulated printout of the results.
The IC analysis consists of four stages (see Figure 1-1
):
1. Eluent Delivery
• Eluent, a liquid that helps to separate the sample ions, carries the
sample through the ion chromatography system. The ICS-90 is an
isocratic delivery system. This means that the eluent composition and
concentration remain constant throughout the run.
• Liquid sample is injected into the eluent stream either manually or
automatically (if an automated sampler is installed).
• The pump forces the eluent and sample through a separator column (a
chemically-inert tube packed with a polymeric resin).
2. Separation
• As the eluent and sample are pumped through the separator column,
the sample ions are separated. In the ICS-90, the mode of separation
is called ion exchange and it is based on the premise that different
sample ions migrate through the IC column at different rates,
depending upon their interactions with the ion exchange sites.
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