**2.1. Immunoaffinity chromatography**

Immunoaffinity chromatography is one of the most popular techniques of affinity derivatived method and it enables to produce ligands in case the ligand required is not available [7]. In this technique, stationary phase comprises of an antibody or antibody-related agent [1]. It is possible to isolate variable subtances using this technique due to high specifity of antibodies [1]. It is reported that immunoaffinity chromatography may be used for natural food contam‐ inants such as aflatoxins, fumonisins and ochratoxins [11].

On the purpose of purification using antibodies as ligands, antibodies initially are immobilized on a support. In order to,bind the ligand on the surface of the support properly, protein A and G are usually used as a bridge which provides enough space for the ligand-protein binding. Columns, dialysis membranes, capillaries or beads may be used in immunoaffinity application which is a non-covalent, irreversible purification process based on highly specific interactions between analyte and antibody [11].

Initially, the antibodies should be purified prior to prepare the immunoaffinity column. Precipitation with ammonium sulfate, ion-exchange chromatography, gel filtration chraoma‐ tography or affinity chromatography may be employed with the aim of antibody purification. Activated beads which are coated with bacterial proteins A or G may be used as the support material. Some parameters may be changed for the elution of the sample solution for example the ionic conditions of mobile phase may be changed or chaotropic buffers may be used [11].

Both small and large analytes can be determined using direct detection in IAC. Additionally it is possible to use this technique either separately or in combination with other chromato‐ graphic techniques [1]. If this technique is performed as part of HPLC system the method can be referred as high performance immunoaffinity chromatography.

Immunoaffinity chromatography is probably the most highly specific of all forms of bioaffinity chromatography. However this technique has some disadvantages such as: this technique relatively high cost, leakage of ligands may accur from the column and sometimes the desorption procedure results in partial denaturation of the bound protein [24].
