A simple and sensitive resonance Rayleigh scattering-energy transfer method for amino acids coupling its Ruhemann's purple and graphene oxide probe

In pH 7.2 KH2PO4-NaOH buffer solution, graphene oxide (GO) has strong resonance Rayleigh scattering (RRS) effect at 400 nm, and amino acid reacted with ninhydrin to form blue-violet complex Ruhemann's purple (RP) with a absorption peak at 400 nm. RPs can strongly adsorbed on the surface of GO, and the RRS donor of GO probes coupled with the receptor of RP that reduced the RRS intensity at 400 nm due to the RRS-energy transfer (RRS-ET) from the GO to RP. With the increase of amino acid concentration, the RRS intensity quenched linearly at 400 nm due to the RRS-ET enhancing. The quenched intensity responds linearly with glutamic acid concentration in the range of 0.2-200 μmol L−1, with a detection limit of 0.08 µmol L−1. This simple and sensitive RRS-ET method was used to detect the content of amino acid in oral liquid, with satisfactory results.