Ninhydrin

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Most amino acids do not have useful UV absorbance or fluorescence emission. This complicates detection of the amino acids. Derivatization of the amino acids is required to permit detection by conventional methods.

Derivatization formation can be done before or after separation (pre- or post-column), depending on the separation method used. A frequently used method is derivatization with Ninhydrin reacting with the N-terminal of amino acids and forming a purple color which can be detected using spectroscopic methods. Also many other derivatization reagents are used.

The third step is: Detection of amino acids