Modified Ninhydrin reagent for the detection of amino acids on TLC plates

Abstract

Ninhydrin is the most well known spray reagent for identification of amino acids due to its high sensitivity. But, it produces same purple/violet color with all amino acids, except proline and hydroxy proline. A new spray reagent, para bromobenzoic acid has been introduced here which produces distinguishable colors with the amino acids with moderately high sensitivity (0.01-1.0) ?g. A probable mechanism for such color formation has also been proposed.