Thin-layer chromatography, known affectionately as TLC, can detect primary amines with electron donors using cinnamaldehyde as a reagent on a TLC plate.

Nanomolar detection of aromatic primary amines, used in drug, pesticide, and polymer synthesis, is possible using a TLC plate coated with inexpensive and non-toxic cinnamaldehyde. Colorless amines produce an almost instantaneous yellow spot with a detection limit between 0.02 and 0.28 µg. The test distinguishes between primary amines with an electron donor and those with an electron acceptor which do not cause a color change. Secondary and tertiary amines also give a negative result. The test is a viable alternative to mass spectrometry and chromatography for these important compounds.

• Simple and rapid detection of aromatic amines using a thin layer chromatography plate
  K. Guo, Y. Chen,
  Anal. Methods, 2010, 2.
  DOI: 10.1039/c0ay00316f