Ion chromatography (IC) is a subset of liquid chromatography methods: ion exchange, ion exclusion, ion pair chromatography. IC is a useful tool for determining the presence and concentration of ions in samples and is utilized in numerous industrial and research settings including a test for authentic tequila and for environmental analyzes such as the determination of anions ($$PO_4^{3-}$$, $$Cl^-$$, $$NO_3^-$$, etc) in surface waters. Ion-exchange is the basic principle behind the removal of cations and anions from drinking water using most commercial, such as Brita, water filters. Ion-exchange is also a natural process that occurs with clay substrates, resulting in the mobility of cations in soils.