Get access

Surface-enhanced Raman spectroscopy (SERS) on silver colloids for the identification of ancient textile dyes. Part II: pomegranate and sumac

Authors

  • Silvia Bruni,

    Corresponding author
    1. Dipartimento di Chimica Inorganica, Metallorganica e Analitica ‘Lamberto Malatesta’, Università degli Studi di Milano, 20133 Milan, Italy
    • Dipartimento di Chimica Inorganica, Metallorganica e Analitica “Lamberto Malatesta”, Università degli Studi di Milano, via G. Venezian 21, 20133 Milano, Italy.
    Search for more papers by this author
  • Vittoria Guglielmi,

    1. Dipartimento di Chimica Inorganica, Metallorganica e Analitica ‘Lamberto Malatesta’, Università degli Studi di Milano, 20133 Milan, Italy
    Search for more papers by this author
  • Federica Pozzi,

    1. Dipartimento di Chimica Inorganica, Metallorganica e Analitica ‘Lamberto Malatesta’, Università degli Studi di Milano, 20133 Milan, Italy
    Search for more papers by this author
  • Anna Maria Mercuri

    1. Laboratorio di Palinologia e Paleobotanica, Dipartimento di Biologia, Università di Modena e Reggio Emilia, 41121 Modena, Italy
    Search for more papers by this author

Abstract

The effectiveness of surface-enhanced Raman spectroscopy (SERS) spectrocsopy on Ag colloids has been successfully demonstrated for the identification of a yellow dye in two ancient wool threads found in the Royal Tumulus of In Aghelachem, Libyan Sahara, belonging to the Garamantian period (2nd–3rd century A.D.). High-performance liquid chromatography (HPLC) highlighted the presence of ellagic acid in the extracts from the threads, excluding other chromophores. This result, together with the abundance of malic acid detected by gas chromatography-mass spectrometry (GC-MS), suggested the possible use of pomegranate rind or sumac berries as source of the yellow dye, both plants being documented in the Fezzan area during the Garamantian period. HPLC analyses and SERS spectra acquired on the extracts of the ancient threads were therefore compared with those obtained from pomegranate and sumac extracts of the corresponding fruits and reference dyed wool samples, allowing us to identify the yellow dye as deriving from pomegranate (Punica granatum L.). SERS spectra of ellagic acid and dyes extracted from pomegranate rind and sumac berries are reported here for the first time. A methodological improvement is also presented, based on the use of NaClO4 as aggregating agent, that leads to a significant increase of the signal-to-noise ratio in the SERS spectra. Copyright © 2010 John Wiley & Sons, Ltd.

Ancillary