Ion Chromatography

Abstract Ion chromatography (IC), which is an important technique within high‐performance liquid chromatography (HPLC), is a chromatographic separation/detection strategy that is applied to the determination of inorganic and organic analyte anions and cations. The methodology consists of three main components: (i) an ion‐exchange column of varying capacity, where the separation occurs; (ii) a suppressor system, which reduces conductivity due to the mobile phase electrolyte; and (iii) a conductivity detector, which is used to detect the analyte ions. Anionic analytes are separated on an anion‐exchange column and analyte cations are separated on a cation‐exchange column. IC, which is routinely applied in water, environmental, health, and food analysis, is a rapid, sensitive, and accurate method for the trace determination of complex mixtures of analyte ions, particularly analyte anions, where no other method offers similar advantages and scope of application, especially when suppressed conductivity detection is employed. Modern IC is characterized by the use of electrolytic eluent generation, electrolytic eluent purification and suppression, and eluent recycling options. Today, the term IC defines a broader group of methodologies applicable to the separation of analyte ions and now also defines the following strategies. Nonsuppressed IC of analyte anions and cations is also possible. In addition, analyte ions can be separated with an ion interaction reagent (ion pair reagent) as a mobile phase additive and a reversed stationary‐phase column rather than an ion‐exchange column; this is often called ion interaction chromatography ( IIC ). Ion exclusion chromatography (IEC), which is a separation of weakly dissociated acid and base analytes on an anion exchanger, is also an important methodology within the field of IC. Modern IC can also be employed for the separation of ionogenic organic molecules from simple low molecular weight carboxylic acids and amines to large organic molecules such as DNA.