Hrdlickova Kuckova S.,Institute of Chemical Technology Prague |
Hrdlickova Kuckova S.,Charles University |
Crhova Krizkova M.,Institute of Chemical Technology Prague |
Pereira C.L.C.,Hercules Laboratory |
And 5 more authors.
Microscopy Research and Technique
This article proposes an innovative methodology which employs nondestructive techniques to assess the effectiveness of new formulations based on ionic liquids, as alternative solvents for enzymes (proteases), for the removal of proteinaceous materials from painted surfaces during restoration treatments. Ionic liquids (ILs), also known as "designer" solvents, because of their peculiar properties which can be adjusted by selecting different cation-anion combinations, are potentially green solvents due totheir low vapour pressure. In this study, two ionic liquids were selected: IL1 (1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4])) and IL2 (1-ethyl-3-methylimidazolium ethylsulphate ([EMIM][EtSO4])). New formulations were prepared with these ILs and two different proteases (E): one acid (E1-pepsin) and one alkaline (E2-obtained from Aspergillus sojae). These formulations were tested on tempera and oil mock-up samples, prepared in accordance with historically documented recipes, and covered with two different types of protein-based varnishes (egg white and isinglass-fish glue). A noninvasive multiscale imaging methodology was applied before and after the treatment to evaluate the cleaning's effectiveness. Different microscopic techniques-optical microscopy (OM) with visible and fluorescent light, scanning electron microscopy (SEM) and atomic force microscopy (AFM)-together with Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) were applied on areas cleaned with the new formulations (IL+E) and reference areas cleaned only with the commercial enzyme formulations (gels). MALDI-TOF proved particularly very useful for comparing the diversity and abundance of peptides released by using different enzymatic systems. © 2014 Wiley Periodicals, Inc. Source
Barata C.,University of Aveiro |
Barata C.,Catholic University of Portugal |
Rocha F.,University of Aveiro |
Cruz A.J.,Polytechnic Institute of Tomar |
And 3 more authors.
Applied Clay Science
Studies based on a scientific approach to materials and techniques used in Portuguese gilded retables from the Baroque are very scarce and focus particularly on works with erudite features and on the characterization of the superficial gold leaf. The conservation and appearance of gilded surfaces, however, depended on the qualities of the clayey ground layer underneath, which is the bole. Colour and texture are closely related to its mineralogical composition.Boles were healing clays. Red to orange varieties could also be used for gilding, usually agglutinated with animal glue when the gold surface was meant to be burnished. Armenian was the name used to identify the best quality material.Microsamples collected from erudite and popular gilded retables, respectively belonging to the city of Oporto and its rural surroundings, were selected for elemental and mineralogical characterization. It was intended to shed light on the characteristics of boles used in Portuguese retables and to understand if there are any differences between materials used in works of distinct artistic quality.Elemental analysis was performed through SEM-EDS. SR-XRD was used for phase identification, performed with a six-circle diffractometer at the DIFFABS beamline of SOLEIL Synchrotron. Portuguese clay standards of identifiable composition and provenance were also analysed.The results suggest that boles are mainly kaolinitic, with variable amounts of illite and smectite. Gypsum was used as an extender. Although the proportions of the main clay minerals are similar in erudite and popular works, in Oporto homogeneity is clearly higher. © 2015 Elsevier B.V. Source
Barrocas Dias C.,Hercules Laboratory |
Barrocas Dias C.,Evora Chemistry Center |
Barrocas Dias C.,University of Evora |
Miranda M.,University of Evora |
And 13 more authors.
Journal of Chemical Education
Onion skins (Allium cepa L.) and hydrated potassium aluminum sulfate were used to dye wool samples. The main chromophores associated with this natural dye source, quercetin and quercetin-4′-O-glucoside, were identified in the dye bath and in wool extracts by high-pressure liquid chromatography (HPLC) equipped with a diode array detector (DAD) with the help of standards. Two procedures were used to extract dye molecules from dyed wool prior to HPLC-DAD qualitative analysis and the analytical methodology used was discussed in terms of the analysis of historical textile pieces dyed with natural sources. © 2013 The American Chemical Society and Division of Chemical Education, Inc. Source
Manhita A.,Hercules Laboratory |
Manhita A.,Evora Chemistry Center |
Ferreira V.,University of Evora |
Vargas H.,Institute of Museums and Conservation |
And 10 more authors.
Wool samples were dyed with madder and alum, copper, and iron salts at different concentration by pre-mordanting (MD) and simultaneous mordanting (M + D) procedures. Samples were artificially aged to identify the influence of the mordant on the madder chromophores photodegradation. A set of analytical techniques was used for complete characterisation of the dyed fibres before and after light exposure, which included colour and chromophore analysis (colourimetry and LC-ESI-MS/MS analysis), determination of mordant ions amounts in the fibres (FAAS and ICP-OES analysis), morphological characterisation of the fibres and punctual chemical analysis (SEM-EDS studies).Fibre colour hue was found to be dependent on the mordant ion nature, mordant bath concentration and dyeing procedure. Mordant ion quantification showed that the uptake of metal ion by the fibres is relatively small, with the Cu ion presenting the highest affinity for the fibre. MD method yields fibres with higher amounts of metal ions and larger chromophore chromatographic peak areas corresponding, in general, to stronger colour hues. Photodegradation was more severe in alum mordant samples and in the first 480. h of light exposure. Chromophore degradation rates are unequal and dependent on the mordant nature, contributing for colour changes observed after light exposure. © 2010 Elsevier B.V. Source
Manhita A.,University of Evora |
Manhita A.,Hercules Laboratory |
Ferreira T.,University of Evora |
Ferreira T.,Hercules Laboratory |
And 5 more authors.
Analytical and Bioanalytical Chemistry
The efficiency of eight different procedures used for the extraction of natural dyes was evaluated using contemporary wool samples dyed with cochineal, madder, woad, weld, brazilwood and logwood. Comparison was made based on the LC-DAD peak areas of the natural dye's main components which had been extracted from the wool samples. Among the tested methods, an extraction procedure with Na2EDTA in water/DMF (1:1, v/v) proved to be the most suitable for the extraction of the studied dyes, which presented a wide range of chemical structures. The identification of the natural dyes used in the making of an eighteenth century Arraiolos carpet was possible using the Na 2EDTA/DMF extraction of the wool embroidery samples and an LC-DAD-MS methodology. The effectiveness of the Na2EDTA/DMF extraction method was particularly observed in the extraction of weld dye components. Nine flavone derivatives previously identified in weld extracts could be identified in a single historical sample, confirming the use of this natural dye in the making of Arraiolos carpets. Indigo and brazilwood were also identified in the samples, and despite the fact that these natural dyes were referred in the historical recipes of Arraiolos dyeing, it is the first time that the use of brazilwood is confirmed. Mordant analysis by ICP-MS identified the widespread use of alum in the dyeing process, but in some samples with darker hues, high amounts of iron were found instead. © 2011 Springer-Verlag. Source