Historical organic dyes: a surface‐enhanced Raman scattering (SERS) spectral database on Ag Lee–Meisel colloids aggregated by NaClO₄

Abstract

Abstract In the present study, several natural organic dyes used in antiquity, especially in textile dyeing, were analysed by surface‐enhanced Raman scattering (SERS) spectroscopy, in order to build a wide database that could integrate the data previously published in the literature. In particular, we reported for the first time the SERS spectra of 11 dyes: dragon's blood, sandalwood, annatto, safflower yellow and red, old fustic, gamboge, catechu, kamala, aloe and sap green. Silver colloids (Ag colloids) prepared according to the Lee–Meisel procedure, i.e. by reduction of a silver nitrate (AgNO 3 ) aqueous solution with trisodium citrate dihydrate, were used as substrate. As its efficiency had been tested in a previous work, sodium perchlorate (NaClO 4 ) 1.8 M was again employed as aggregating agent, giving the best results when added to the silver nanoparticles after the analyte. Copyright © 2011 John Wiley & Sons, Ltd.