Mise en évidence de la présence de matière organique dans un ciment d'aragonite botryoidale par spectrométrie infrarouge à transformée de Fourier (FTIR)

Abstract : The FTIR method has been tested on two kinds of aragonite: the first of biological origin from a Recent Acropora and the second of diagenetic origin from a marine botryoidal cement from reefal limestone of Mururoa atoll. The FTIR spectra of bulk powders revealed the presence of an organic phase in the cement. The infrared spectrometry of soluble and insoluble decalcified phases showed the presence of proteinaceous and sugar compounds. In the spectra of the insoluble phase of botryoidal cement, the band of A amide is less intense than in Acropora, the one of the I amide is missing and one of the II amide is insignificant. The chromatography of the soluble phase shows that the peaks of the cement correspond to lighter masses than those of Acropora. In both cases, the peak of lighter masses is the most important and the wavelengths of higher absorption are lower than 230nm, this indicating peptide linkages.