Ion Chromatography
Also known as: IC, ion-exchange chromatography, IEC
Ion chromatography is a liquid chromatography method that separates ions and polar molecules based on their relative affinity for the ion exchange resin in the column. Developed by Hamish Small in 1975, it combines ion-exchange separation with conductivity detection, enabling rapid, sensitive, and simultaneous determination of multiple ions in a single analysis. Ion chromatography has become an indispensable tool for monitoring environmental pollutants, analyzing food and pharmaceutical products, and studying complex ionic mixtures.
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When to use it
Ion chromatography is the method of choice for determining multiple inorganic ions (nitrate, phosphate, sulfate, chloride, etc.) simultaneously in environmental, pharmaceutical, and food samples. Use IC when high selectivity and sensitivity for ionic analytes are required, when non-destructive detection is preferred, or when a wide range of ions need to be analyzed in one run. It excels in applications where traditional titrimetry is slow or where matrix interference is problematic.
Strengths & limitations
- Simultaneous determination of multiple ions in a single analysis
- High selectivity and sensitivity, especially with conductivity suppression
- Non-destructive detection allows downstream analysis or collection of separated ions
- Rapid analysis time compared to traditional wet chemical methods
- Compatible with a wide variety of detectors (conductivity, UV, amperometric, mass spectrometry)
- Requires properly buffered, ion-free water and high-purity chemicals for eluent preparation
- Background conductivity of the eluent can limit sensitivity for very low analyte concentrations
- Some organic molecules and non-ionic species are not easily detected by standard conductivity detectors
- Column conditioning and suppressor regeneration add to maintenance burden
Frequently asked
What is the role of the suppressor in ion chromatography?
The suppressor is a post-column reactor that chemically converts the excess eluent salt (background ions) into a weakly ionized compound, dramatically reducing the background conductivity. This suppression allows the detector to measure small ion peaks with high sensitivity and contrast against a very low baseline, improving both detection limits and peak resolution.
How do I choose between anion and cation exchange columns?
Use an anion-exchange column (negatively charged resin) to separate negatively charged ions (anions such as chloride, nitrate, phosphate, sulfate). Use a cation-exchange column (positively charged resin) to separate positively charged ions (cations such as sodium, potassium, calcium, magnesium). Some laboratories run both methods to obtain a complete ionic profile of a sample.
Why is peak tailing sometimes observed in ion chromatography?
Peak tailing (asymmetrical peak shape) often results from secondary interactions between the analyte and residual silanol groups on the column packing, especially when the sample contains ions at high concentration or when the column is not properly buffered. Using buffered eluents and properly conditioned columns minimizes this effect.
Can ion chromatography separate organic ions?
Yes. Ion chromatography can separate organic anions (acetate, citrate, oxalate) and organic cations (ammonium, tetramethylammonium) using appropriately selected columns and eluents. However, organic molecules without ionic groups are typically not retained and will not be separated or detected.
What is gradient elution in ion chromatography?
Gradient elution involves progressively increasing the concentration of the eluent salt during the run, causing ions with weak column affinity to elute early and ions with strong affinity to elute later. This improves separation of analytes with diverse ion-exchange affinities and reduces overall analysis time compared to isocratic (constant eluent concentration) methods.
Sources
- Small, H., Stevens, T. S., & Bauman, W. C. (1989). Novel ion exchange chromatographic method using conductometric detection. Analytical Chemistry, 47(11), 1801–1809. DOI: 10.1007/978-1-4899-2542-8_7 ↗
- Weiss, J. (2004). Handbook of Ion Chromatography (3rd ed.). Wiley-VCH. ISBN: 978-3527289721
- Jackson, P. E., Haddad, P. R., & Alexander, P. W. (1997). Advances in ion chromatography. Journal of Chromatography A, 789(1-2), 17–33. link ↗
How to cite this page
ScholarGate. (2026, June 3). Ion Chromatography. ScholarGate. https://scholargate.app/en/analytical-chemistry/ion-chromatography
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
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