Ion Chromatography:

It is being routinely used for the separation of inorganic anions such as Cl^-, Br^-, F^-, SO₄^{2 -} , NO₃^- , NO₂^- , and PO^3-₄ at ppm levels in surface waters, industrial effluents, food products, pharmaceuticals and clinical samples. Typical ion chromatograms in Figure show the analysis of various anions and cations using two column flow method.  Thus, inorganic cations such as Na⁺, K⁺ and NH₄⁺ can be monitored in foods such as dietetic foods low in sodium, and urine samples where the efficiency of the separation is markedly influenced by the use of complexing agent in the eluent. However, separation of organic acids and bases, alkali, alkaline earth and transition metal cations are also being achieved. Ion-exchange resins having a proportion of the ionic sites replaced with hydrophobic reversed phase groups commonly used in HPLC columns, typically octadecylsilane, enable separation of both non-ionic and ionic species in a mixture. It has become a widely used technique in a pathological and environmental analysis laboratory where commercial instruments are used.