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The aim of the present study was to establish a mild extraction and universal method to characterize madder lakes of Rubia tinctorum by liquid chromatography coupled with a photodiode array detector. To analyze the lakes, anthraquinone molecules must be decomplexed of metal links. To this end, two processes, one ultrasound and the other microwave, were improved in association with two solutions, an oxalic acid solution (0.5 M in MeOH/H 2 O 50/50) and an acetic acid buffer solution (1 M). First, the decomplexation of an alizarin experimental lake was optimized in comparison with a reference method using a strong acid. The microwave process used oxalic acid and increased the decomplexation yield of alizarin (71%) compared with the reference method (31%). Second, different madder experimental lakes, which were prepared using different metal salts, were decomplexed. The obtained results suggest that the use of microwave associated with oxalic acid solution is the most universal method providing a decomplexation of anthraquinones from lakes without hydrolysis of glycosidic compounds occurring. • Synthesis of madder lakes using five different metallic cations. • Decomplexation of metal-complex dyes by two separate processes: ultrasound and microwave. • Development of a universal, efficient, and nondenaturing method for the study of madder lakes. [ABSTRACT FROM AUTHOR]

Six objects of Beninese cultural heritage provided by African and Confluences museums of Lyon (France) were the focus of this study. The characterization of colored compounds was achieved using: microchemical tests, Fourier transform infrared spectroscopy and liquid chromatography coupled to a photodiode array detector. The main results reflect the presence of organic compounds like indigotin, 2‐hydroxynaphthoquinone, and mineral ions such as Al3+, S2−, Na+, and Fe3+. Dyes were identified from Philenoptera cyanescens (Yoruba indigo) and Lawsonia inermis L. (henna); pigments were identified as laundry blue, Prussian blue, and iron oxides. All of these data therefore make possible the conservation and the restoration of these objects while maintaining their visual and functional integrity. [ABSTRACT FROM AUTHOR]

Abstract: Flavonol compounds present in green fruits of Rhamnus species (Rhamnus saxatilis, Rhamnus alaternus and Rhamnus catharticus) were studied. The objective is to compare the chemical composition of the three Rhamnus species in order to distinguish them. Liquid chromatography was employed for the separation of the analytes and the detector is an ion trap mass spectrometer in positive ESI mode. The aglycones part was constituted by usual flavonols as quercetin, kaempferol, isorhamnetin, rhamnetin, rhamnocitrin and rhamnazin while heterosidic part was an O-rhamninoside or O-acetyl-rhamninoside linked in position 3 or 4′ on flavonol skeleton. The UV/Visible spectroscopy has permitted to determine the glycosylation site on the flavonol, and liquid chromatography was used to confirm the glycoside sequence and aglycone part. Each Rhamnus species was characterized by leading compounds as O-acetyl-rhamninoside derivatives for R. saxatilis, 4′-O-rhamninoside for R. alaternus and R. catharticus. Quercetin-4′-O-rhamninoside is only present in R. alaternus species permitting to discriminate it. [Copyright &y& Elsevier]

A chromatographic method using fluorescing derivatization was developed for the analysis of triterpenoids in natural resins. The separation was performed using a Luna-C18 column, an acetonitrile-water eluant mixture, a flow-rate of 1 mL · min−1. The fluorescent compounds were detected at 530 nm (excitation at 347 nm). A derivatization reaction of hydroxyl groups of triterpenoids using dansyl chloride is described; this process appeared unusual and provided some novelty. The detection limits were obtained in the range of 0.15–0.45 ng/mL (S/N = 3) for dansylated standard compounds. The described procedure allowed the simultaneous determination of twelve triterpenoids present in frankincense species (Boswellia carteri and B. frereana) and was successfully applied to an archaeological sample coming from an Egyptian mummy. Two other resinous materials, dammar and mastic resins employed in Cultural Heritage, were also studied, in which nine and seven triterpenoids are respectively characterized. [ABSTRACT FROM PUBLISHER]

Abstract: A reverse phase liquid chromatography-photodiode array detection method is developed for the characterization of ancient samples of madder. In the past, modifications of the madder chemical composition were carried out by hydrolysing the plant dye precursors in order to increase its red power, the aim of this transformation being to concentrate the red colour of the matter. After extraction of madder dyes in a water-methanol mixture, different anthraquinonic compounds were identified through the chemical constituents present in a garancine sample and in the two madder species growing in the Mediterranean area: Rubia tinctorum and R. peregrina. These two species comprise alizarin, purpurin, lucidin, rubiadin and pseudopurpurin for aglycones and, lucidin primeveroside, ruberythric acid, galiosin and rubiadin primeveroside for heterosidic precursors. These compounds were identified through retention times and UV spectra in comparison with pure standards. Six ancient materials belonging to the collection of the Roure Museum in Avignon (France) and dating from the nineteenth century are characterized as hydrolysed madder (garancine), synthetic alizarin and R. tinctorum roots. A colorimetric study is performed to compare the colour of each sample according to its chemical composition. [Copyright &y& Elsevier]

Abstract: An extraction method of madder (Rubia tinctorum) roots dyes is established and optimized to obtain the original chemical composition. A central composite design (CCD) was developed to specify the importance of the three major factors studied (time, temperature and solvent composition) affecting the ultrasound-assisted extraction of this matrix. A preliminary granulometric study of madder roots is realized in the aim to determine the optimal particles size corresponding to the best ultrasound effects. A comparison with the classical extraction method of madder dyes by reflux is described. The identification of the constituents of R. tinctorum is carried out by liquid chromatography coupled with a photodiode array detector (LC–PDA). Anthraquinonic aglycone and heterosidic dyes compounds are characterized by retention time and UV spectrum: alizarin (1,2-dihydroxyanthraquinone), purpurin (1,2,4-trihydroxyanthraquinone), lucidin (1,3-dihydroxy-2-hydroxymethylanthraquinone), rubiadin (1,3-dihydroxy-2-methylanthraquinone), xanthopurpurin (1,3-dihydroxyanthraquinone), pseudopurpurin (1,2,4-trihydroxy-3-carboxyanthraquinone), lucidin primeveroside, ruberythric acid (alizarin primeveroside), galiosin (pseudopurpurin primeveroside) and rubiadin primeveroside. The optimal experimental conditions are 18min, 36°C and 37/63 MeOH/H2O (v/v). [Copyright &y& Elsevier]

Abstract: Contribution of analytical chemistry to the study of styrax and benzoin botanical exudates. For several resins, gaps in botanical classification and ambiguities in their designation induce difficulties to correlate with precision botanical species and chemical composition. It is the case of balsamic resins called styrax and benzoins, for which there are important linguistic, botanical and chemical confusions. This study by Fourier Transform Infrared (FTIR) spectroscopy and High-Performance Liquid Chromatography (HPLC) of several resinous samples made it possible to specify the chemical and botanical membership of these substances at the origin of many interrogations. It also provided interesting information about the ways to obtain or to transform the resinous matters while evoking the possibility of adulterations or confusions with dammar resin issued from geographically close vegetable species. To cite this article: M. Hovaneissian et al., C. R. Chimie 9 (2006) . [Copyright &y& Elsevier]