Use of ninhydrin for detection of silylated amino acids

Protein structure elucidation is very dependent on the detection of its constituent amino acids, because these are the structural units of proteins. They are also found in the free state in a different natural products. Several specific and non-specific reagents have been reported for detection of amino acids [1–6]; of these, ninhydrin is a widely accepted non-specific reagent with high sensitivity. The formation of an identical color (purple/violet) with all amino acids except proline and hydroxy proline is, however, a problem if specific detection of the amino acids is required.