Detection of amino acids on TLC plates with modified ninhydrin reagent

Natural Product Laboratory, Department of Chemistry, The University of Burdwan, Burdwan-713 104, West Bengal, India E-mail : sinhababu04@yahoo.co.in Fax : 91-342-2530452/2634200 Manuscript received online 28 January 2013, revised 04 February 2013, accepted 09 February 2013 Thin layer chromatography is an important tool for detecting amino acids by several spray reagents. 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 modified ninhydrin reagent, para-chlorobenzaldehyde has been introduced here which produces distinguishable colors with the amino acids with moderately high sensitivity (0.03–1.0 µg). A probable mechanism for such color formation and the color pictures of the chromatograms by digital camera are also included here