Analytical and Bioanalytical Chemistry (v.399, #9)
Analytical chemistry for cultural heritage: a key discipline in conservation research by Rocco Mazzeo; Aldo Roda; Silvia Prati (2885-2887).
is Professor of Chemistry for Cultural Heritage at Bologna University, where he is actively involved in formal education in science for conservation and performs research in micro-FTIR mapping and imaging spectroscopic techniques applied to the study of painted works of art. is Professor of Analytical Chemistry at Bologna University. His main research interests include the development of ultrasensitive bio-chemiluminescence imaging techniques for the localization of target molecules (proteins, nucleic acids) in biological samples, such as cells and tissues. is Researcher of Chemistry for Cultural Heritage at Bologna University, where she is actively involved in formal education in science for conservation and performs research in micro-FTIR mapping and imaging spectroscopic techniques applied to the study of painted works of art.
Development of a multiplexed chemiluminescent immunochemical imaging technique for the simultaneous localization of different proteins in painting micro cross-sections by Giorgia Sciutto; Luisa Stella Dolci; Angela Buragina; Silvia Prati; Massimo Guardigli; Rocco Mazzeo; Aldo Roda (2889-2897).
The identification and localization of organic components in the complex stratigraphy of paintings play a crucial role in studies of painting techniques and authentication, restoration, and conservation of artworks. Much scientific effort has been expended for the development of analytical approaches suitable for the investigation and characterization of organic substances, allowing high sensitivity, specificity, and spatial resolution. Proteins (e.g., ovalbumin, casein, and collagen from different animal sources) are one of the classes of organic substances most widely used as painting materials. The analytical techniques commonly used for their analysis (micro Fourier transform infrared spectroscopy, chromatographic techniques, and proteomic approaches) have limits related to the lack of specificity or to the absence of information concerning the stratigraphic localization of the detected proteins. Immunological techniques are a promising alternative approach for the characterization of proteins in artworks. Thanks to the high specificity of antigen–antibody reactions, these techniques are widely used for the analysis of proteins in bioanalytical and clinical chemistry and recently they have been successfully applied in the field of science for conservation of cultural heritage. The present research aimed to develop an ultrasensitive chemiluminescent immunochemical procedure for the simultaneous localization of ovalbumin and bovine casein (two common proteins found in binding media or varnishes of artistic and archaeological samples) in resin-embedded painting micro cross-sections. The possibility of performing the simultaneous identification of different proteins in painting cross-sections is of particular relevance in the field of cultural heritage because samples are often small and available in a limited number; therefore, the maximum amount of information must be obtained from each of them. Figure Left: image of a cross section of a painting standard sample with layers of milk and egg tempera with smalt pigment (blue grains). Right: localization of bovine casein and ovalbumin in the cross section as assessed by the multiplexed chemiluminescence immunochemical imaging technique (the signals corresponding to bovine casein and ovalbumin are displayed in shades of red and blue, respectively).
Keywords: Chemiluminescence; Cultural heritage; Imaging; Immunoassay; Painting cross-section; Protein binders
Development of an analytical procedure for evaluation of the protective behaviour of innovative fungal patinas on archaeological and artistic metal artefacts by Edith Joseph; Anaële Simon; Silvia Prati; Marie Wörle; Daniel Job; Rocco Mazzeo (2899-2907).
In the literature, the ability to transform metal compounds into metal oxalates has been reported for different species of fungi. This could be an innovative conservation method for archaeological and artistic metal artefacts. In fact, with a high degree of insolubility and chemical stability even in acid atmospheres (pH 3), metal oxalates provide the surface with good protection. Within the framework of the EU-ARTECH project, different fungal strains have been used to transform existing corrosion patinas on outdoor bronze monuments into copper oxalates, while preserving the physical appearance of these artefacts. Given the promising results obtained with this first attempt, the same approach is now applied within the BAHAMAS (Marie Curie Intra European Fellowship action) project, but extended to other metal substrates, for example iron and silver, which are frequently found in cultural heritage artworks and also encounter several problems of active corrosion. The research is investigating the formation mechanisms and adhesion properties of the newly formed metal oxalates by means of complementary analytical techniques (X-ray diffraction (XRD), FTIR microscopy, Raman microscopy, scanning electron microscopy (SEM-EDS), electrochemical impedance spectroscopy (EIS), colorimetry). For each metal substrate, the most appropriate fungal strain is going to be identified and applied to corroded sheets and the novel fungal treatment compared with those used so far. Treated metal sheets will be monitored during 1-year exposure to different cycles of artificial ageing, to evaluate the corrosion resistance of the fungal patinas obtained. The objective of this contribution is to present the first results achieved so far on naturally corroded bronze sheets during the EU-ARTECH project and the analytical procedure used for the testing of the proposed treatment performances during the BAHAMAS project.
Keywords: Corrosion; Metal artefacts; Protective treatments; Metal immobilization; Oxalates; Metal stabilisation
Electron energy loss spectroscopy elucidates the elusive darkening of zinc potassium chromate in Georges Seurat’s A Sunday on La Grande Jatte—1884 by F. Casadio; S. Xie; S. C. Rukes; B. Myers; K. A. Gray; R. Warta; I. Fiedler (2909-2920).
The color darkening of selected brushstrokes of Georges Seurat’s A Sunday on La Grande Jatte—1884 was noted as early as 1892. Artificial aging of model systems containing zinc yellow (K2O·4ZnCrO4·3H2O) mixed with linseed oil successfully replicated the phenomena observed on La Grande Jatte. Electron energy loss spectroscopy measurements performed on the uppermost few microns of thin sections of the paint layers (obtained with focused ion beam milling) determined that samples which turned olive green (aged at 90% RH, with SO2 and light) contain mostly the altered species Cr(III) and that the ochre-yellow coloration of specimens aged at 50% RH with SO2 and light is due to the presence of dichromate ions (Cr (VI)). The altered species are only present in the first few microns of paint and are likely poorly crystalline, so that they eluded other types of bulk and surface measurements, but they create a substantial color alteration at the surface of the paint films. A similar phenomenon was confirmed on a sample from La Grande Jatte, where Cr(III) and Cr(VI) dichromate ions were detected in the ochre-colored, altered brushstrokes of zinc yellow. Laboratory simulations demonstrated that the equilibrium between chromate and dichromate ions is reversible within the paint film and that the orange dichromate ions can be transformed back into bright yellow chromates by exposure to highly alkaline gases. Figure Georges Seurat, A Sunday on La Grande Jatte—1884, The Art Institute of Chicago. In the inset: Electron Energy Loss spectra of Cr rich pigment particles on a sample of paint from a darkened dot of La Grande Jatte, documenting Cr (III) and Cr(VI) dichromate alteration species
Keywords: Zinc potassium chromate; Chromate paint; Electron energy loss spectroscopy (EELS); Artificial aging; Cultural heritage; Alteration
Study of behaviour on simulated daylight ageing of artists’ acrylic and poly(vinyl acetate) paint films by María Teresa Doménech-Carbó; Miguel F. Silva; Elvira Aura-Castro; Laura Fuster-López; Stephan Kröner; María Luisa Martínez-Bazán; Xavier Más-Barberá; Marion F. Mecklenburg; Laura Osete-Cortina; Antonio Doménech; José Vicente Gimeno-Adelantado; Dolores Julia Yusá-Marco (2921-2937).
This work proposes a multi-method approach that combines advanced microscopy (SEM/EDX, AFM) and spectroscopy (UV-vis and FTIR) techniques. This approach not only characterises the behaviour of the additives of two commercial poly(vinyl acetate) (PVAc) and acrylic emulsion paints but also simultaneously characterises the changes in chemical composition and morphology observed in the paint films as a result of ageing due to the paints being exposed to an intense source of simulated daylight. In parallel, a series of mechanical tests were performed that correlate the chemical changes in composition and the changes observed in the films’ mechanical properties. This work was a comparative study between both types of acrylic and PVAc paints. The results obtained are of great interest for the modern paint conservation field as they provide valuable information on the mid- and long-term behaviours of these synthetic paints. Figure Tensile test of phthalocianyne blue Liquitex® paint film
Keywords: Surfactant; Acrylic artists’ paint; PVAc paint; FTIR spectroscopy; AFM; Tensile tests
Plastic matters: an analytical procedure to evaluate the degradability of contemporary works of art by Massimo Lazzari; Ana Ledo-Suárez; Thaïs López; Dominique Scalarone; M. Arturo López-Quintela (2939-2948).
The most significant results concerning a chemical study to evaluate the degradability of polymeric components in four contemporary works of art, partially or completely realized in plastics, are presented and discussed in this paper. The procedure applied is mainly based on the use of Fourier transform IR and UV–vis spectroscopies and pyrolysis–gas chromatography/mass spectrometry, and consists of the following steps: (1) compositional analysis of the artworks, with particular attention to components which may have a negative effect on the overall ageing; (2) evaluation of the actual state of conservation; (3) investigation of the accelerated ageing of reference polymer samples; and (4) monitoring of the natural ageing of the artworks. On such a basis, the following could be concluded. Stage Evidence by Loris Cecchini is made of poly(ether urethane) elastomer which contains a high amount of phthalates. Their exudation gives a sticky appearance to the artwork and their removal during ageing is the main cause of the loss of flexibility. The latex used by Andrés Pinal for tailoring Traxe de Home is a natural polyisoprene, whose oxidative degradation accounts for the extensive deterioration and yellowing of the artwork. The plaster sculptures of 3D Bodyscans 1:9 by Karin Sander are coated with an aliphatic epoxy resin. Its oxidation with formation of amides is the cause of the surface yellowing. The adhesive used by Dario Villalba for Tierra, Ladrillo y Agua is a commercial poly(vinyl acetate). Simulated photoageing suggests a fast deterioration due to deacetylation and cross-linking, which possibly is the main reason for the actual detachment of debris from the support. Figure Investigated artworks from the Contemporary Art Museum of Santiago de Compostela (Spain), partially or completely realized in plastics
Keywords: Polymers; Attenuated total reflectance Fourier transform IR spectroscopy; Cultural heritage; Accelerated ageing tests
Spectroscopic evaluation of the environmental impact on black crusted modern mortars in urban–industrial areas by N. Prieto-Taboada; M. Maguregui; I. Martinez-Arkarazo; M. A. Olazabal; G. Arana; J. M. Madariaga (2949-2959).
A multianalytical characterisation of black crusted modern construction materials from buildings located in the Bilbao Metropolitan area (North Spain) was carried out. According to the mineral composition determined by Raman spectroscopy, calcite and hematite were the major compounds found while aragonite, limonite, rutile, quartz and some aluminosilicates such as obsidian or amazonite (KAlSi3O8) were also present in minor percentages. As deterioration products, gypsum and anhydrite were widely found not only in the surface but also in the inner part of strongly deteriorated samples. Coquimbite (Fe2(SO4)3·9H2O) was identified as well in the most protected facade where high amounts of Fe, having probably an anthropogenic origin, were measured by micro X-ray fluorescence (μ-XRF). Zn was found to be in high amounts while Cu, Pb, Ti, Mn, Sr and K were identified as minor elements. Considering the non-expected concentrations found for some anthropogenic elements, a sequential extraction was carried out in order to determine their chemical form by means of ion chromatography and inductively coupled plasma mass spectrometry. The orientation of the facades, which had a different influence from rain washing and industrial and traffic impact, was shown to affect the accumulation of different compounds in the black crust. Finally, the MEDUSA software was used to simulate the reactions among the original compounds, deposited pollutants and the atmospheric acid gases in order to explain the presence of the decaying species found. Figure Multianalytical Speciation protocol applied on the analysis of modern mortars
Keywords: Acid gases; Black crust; Coquimbite; Modern mortars; Raman spectroscopy; Sequential extraction
Characterization and identification of acrylic binding media: influence of UV light on the ageing process by Valentina Pintus; Manfred Schreiner (2961-2976).
This study characterizes and identifies two different acrylic binding media such as Plextol® D498 and Primal® AC33, which are widely used in modern and contemporary art. In order to investigate their fast photooxidative deterioration when exposed to ultraviolet (UV) light, ageing studies on these materials were carried out. For this purpose, pure synthetic materials but also mixed with different inorganic pigments were identified and characterized before and after UV exposure by means of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Particular attention was paid to the comparison of two different analytical methods: (1) single-shot method based on a pyrolysis for the analysis of polymers and (2) double-shot method, which allows a unique combination of thermal desorption for the analysis of volatile compounds and pyrolysis of the polymers themselves. These analyses have been complemented by Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) studies. The comparison of the results obtained from unaged samples and UV-aged clearly showed material alterations as well as the formation of new products, which were recorded by FTIR-ATR. Generally, these changes were more pronounced when the acrylic binding media were mixed with pigments. The double-shot technique of Py-GC/MS additionally allowed the detection of the phenolic antioxidant in unaged Plextol® D498, but no oxidation products could be identified by Py-GC/MS in all samples.
Keywords: Py-GC/MS; FTIR-ATR; Double-shot technique; Acrylic polymer; Paint materials; UV ageing
Fluorescence and Fourier-transform infrared spectroscopy for the analysis of iconic Italian design lamps made of polymeric materials by Francesca Toja; Austin Nevin; Daniela Comelli; Marinella Levi; Rinaldo Cubeddu; Lucia Toniolo (2977-2986).
The preservation of design object collections requires an understanding of their constituent materials which are often polymeric blends. Challenges associated with aging of complex polymers from objects with an unknown physical history may compromise the interpretation of data from analytical techniques, and therefore complicate the assessment of the condition of polymers in indoor museum environments. This study focuses on the analysis of polymeric materials from three well-known Italian design lamps from the 1960s. To assess the degree of chemical modifications in the polymers, non-destructive molecular spectroscopic techniques, Fourier-transform infrared (FTIR) and fluorescence spectroscopy, have been applied directly on the object surfaces using an optical fiber probe and through examination of micro samples. FTIR spectra of the different polymers, polyvinylacetate (PVAc) for the lamps Taraxacum and Fantasma, and both acrylonitrile–butadiene–styrene polymer (ABS) and cellulose acetate (CA) for the lamp Nesso, allowed the detection of ongoing deterioration processes. Fluorescence spectroscopy proved particularly sensitive for the detection of molecular changes in the polymeric objects, as the spectra obtained from the examined lamps differ significantly from those of the unaged reference materials. Differences in fluorescence spectra are also detected between different points on the same object further indicating the presence of different chemical species on the surfaces. With the aid of complementary data from FTIR spectroscopy, an interpretation of the emission spectra of the studied polymeric objects is here proposed, further suggesting that fluorescence spectroscopy may be useful for following the degradation of historical polymeric objects.
Keywords: Polyvinylacetate; Acrylonitrile–butadiene–styrene polymer; Cellulose acetate; FTIR spectroscopy; Fluorescence spectroscopy; Design objects; Cultural heritage
Tracing the biological origin of animal glues used in paintings through mitochondrial DNA analysis by Emidio Albertini; Lorenzo Raggi; Manuela Vagnini; Alessandro Sassolini; Alessandro Achilli; Gianpiero Marconi; Laura Cartechini; Fabio Veronesi; Mario Falcinelli; Brunetto Giovanni Brunetti; Costanza Miliani (2987-2995).
We report the development of a suitable protocol for the identification of the biological origin of binding media on tiny samples from ancient paintings, by exploitation of the high specificity and high sensitivity offered by the state-of-the art DNA analysis. In particular, our aim was to molecularly characterize mitochondrial regions of the animal species traditionally employed for obtaining glues. The model has been developed using aged painting models and then tested to analyze the organic components in samples from the polychrome terracotta Madonna of Citerna by Donatello (1415–1420), where, by GC–MS and FTIR spectroscopy, animal glues and siccative oils were identified. The results obtained are good in terms of both sensibility and specificity of the method. First of all, it was possible to confirm that Donatello used animal glue for the preparation of the painted layers of the Madonna of Citerna and, specifically, glue derived from Bos taurus. Data obtained from sequencing confirm that each sample contains animal glue, revealing that it was mostly prepared from two common European taurine lineages called T2 and T3. There is one remarkable exception represented by one sample which falls into a surviving lineage of the now extinct European aurochs. Figure One of the four microscale samples of the “Madonna of Citerna” collected during restoration (upper) and amplicons obtained using primers specific for cattle, swine, rabbit and sheep on DNA isolated from the 4 microscale samples (S1, S2, S3 and S4)
Keywords: Nucleic acids; PCR; Mitochondrial DNA; Proteinaceous binding media; Taurine phylogenesis
An improved method of protein localization in artworks through SERS nanotag-complexed antibodies by Julie Arslanoglu; Stephanie Zaleski; John Loike (2997-3010).
There are several analytical techniques currently in use in conservation science to identify proteins in artworks. However, as is often the case, the determination of the exact location of a protein in a complex layer structure is challenging due to difficulty in separating layers. Localization of the protein in a cross-section has been demonstrated through attenuated total reflectance-Fourier transform infrared mapping and imaging as well as chemiluminescent and fluorescent-labeled antibodies; however, these techniques either require expensive instrumental setups or produce results that can be challenging to interpret. This paper will present research using surface-enhanced Raman scattering (SERS) nanotags complexed to secondary antibodies in conjunction with primary antibodies for the localization of ovalbumin, collagen, and casein in cross-sections from replicas and artworks containing avian egg, animal glue, or casein binders. The advantages of this technique over the others are (1) the detection method is a Raman microscope, equipment found in several museum laboratories; (2) the distinctive SERS signal from the nanotag increases the detection limit of the protein and decreases the interference from other colorants present in the cross-section layers; and finally, (3) the large (120 nm) SERS-labeled antibodies do not appear to penetrate into the cross-section, eliminating the risk of spurious signal and misidentification. Any agglomerations due to surface texture are clearly visible under normal illumination and can be avoided easily during analysis or removed with a light polish. This technique not only allows protein localization in multilayered samples while preserving the stratigraphic information but also retains the protein specificity of the antibody approach. Figure
Keywords: ELISA; SERS; Antibody; Nanotag; Localization; Protein; Paint cross-section
Development of an analytical protocol for a fast, sensitive and specific protein recognition in paintings by enzyme-linked immunosorbent assay (ELISA) by M. Palmieri; Manuela Vagnini; L. Pitzurra; P. Rocchi; B. G. Brunetti; A. Sgamellotti; L. Cartechini (3011-3023).
Enzyme-linked immunosorbent assay (ELISA) analysis of proteins offers a particularly promising approach for investigations in cultural heritage on account of its appreciated properties of being highly specific, sensitive, relatively fast, and cost-affordable with respect to other conventional techniques. In spite of that, it has never been fully exploited for routine analyses of painting materials in consideration of several analytical issues that inhibited its diffusion in conservation science: limited sample dimensions, decrease of binder solubility and reduced availability of antibody bonding sites occurring with protein degradation. In this study, an ELISA analytical protocol suited for the identification of aged denatured proteins in ancient painting micro-samples has been developed. We focused on the detection of bovine β-casein and chicken ovalbumin as markers of bovine milk (or casein) and chicken albumen, respectively. A systematic experimentation of the ELISA protocol has been carried out on mock-ups of mural and easel painting prepared with 13 different pigments to assess limits and strengths of the method when applied for the identification of proteins in presence of a predominant inorganic matrix. The analytical procedure has been optimized with respect to protein extraction, antibodies’ concentrations, incubation time and temperature; it allows the detection of the investigated proteins with sensitivity down to nanograms. The optimized protocol was then tested on artificially aged painting models. Analytical results were very encouraging and demonstrated that ELISA allows for protein analysis also in degraded painting samples. To address the feasibility of the developed ELISA methodology, we positively investigated real painting samples and results have been cross-validated by gas chromatography–mass spectrometry.
Keywords: Immunoessays/ELISA; Painting binders; Casein; Ovalbumin
Identification of the finishing technique of an early eighteenth century musical instrument using FTIR spectromicroscopy by Loïc Bertrand; Laurianne Robinet; Serge X. Cohen; Christophe Sandt; Anne-Solenn Le Hô; Balthazar Soulier; Agnès Lattuati-Derieux; Jean-Philippe Echard (3025-3032).
The study of varnishes from musical instruments presents the difficulty of analysing very thin layers of heterogeneous materials on samples most of which are generally brittle and difficult to prepare. Such study is crucial to the understanding of historical musical instrument varnishing practices since written sources before 1800 are very rare and not precise. Fourier-transform infrared (FTIR) spectroscopy and imaging methods were applied to identify the major chemical components within the build-up of the varnish layers on a cello made by one of the most prominent French violin-makers of the eighteenth century (Jacques Boquay, ca. 1680–1730). Two types of FTIR imaging methods were used: scanning with a synchrotron-based microscope and full-field imaging using a 2D imager with a conventional source. An interpretation of the results obtained from these studies on the Boquay cello is that the maker first applied a proteinaceous layer, probably gelatine-based animal glue. He later applied a second layer based on a mixture of a drying oil and diterpenic resin from Pinaceae sp. From an historical perspective, the results complement previous studies by describing a second technique used for musical instrument finishes at the beginning of the eighteenth century in Europe. Figure FTIR spectromicroscopy study of a cello made by the luthier Jacques Boquay (Paris, ca. 1680-1729) shows that the maker first applied a proteinaceous layer, probably gelatine-based animal glue.
Keywords: Fourier transform infrared (FTIR) imaging; Historical materials; Musical instruments; Varnish
XAS study on copper red in ancient glass beads from Thailand by Wantana Klysubun; Yatima Thongkam; Sorapong Pongkrapan; Krit Won-in; Jiraroj T-Thienprasert; Pisutti Dararutana (3033-3040).
Glass has been used in ornaments and decorations in Thailand for thousands of years, being discovered in several archeological sites and preserved in museums throughout the country. To date only a few of them have been examined by conventional methods for their compositions and colorations. In this work we report for the first time an advanced structural analysis of Thai ancient glass beads using synchrotron X-ray absorption spectroscopy (XAS) and energy-dispersive X-ray (EDX) spectrometry. Four samples of ancient glass beads were selected from four different archeological sites in three southern provinces (Ranong, Krabi and Pang-nga) of Thailand. Archaeological dating indicated that they were made more than 1,300 years ago. A historically known method for obtaining a red color is to add compounds containing transition elements such as gold, copper, and chromium. For our samples, EDX spectrometry data revealed existing fractions of iron, copper, zinc, and chromium in ascending order. Thus, copper was selectively studied by XAS as being potentially responsible for the red color in the glass beads. K-shell X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) of copper were recorded in fluorescence mode using an advanced 13-element germanium detector. Comparisons with XANES spectra of reference compounds identified two major forms of copper, monovalent copper and a metallic cluster, dispersed in the glass matrix. The cluster dimension was approximated on the basis of structural modeling and a theoretical XANES calculation. As a complement, EXAFS spectra were analyzed to determine the first-shell coordination around copper. XAS was proven to be an outstanding, advanced technique that can be applied to study nondestructively archaeological objects to understand their characteristics and how they were produced in ancient times.
Keywords: Copper red; Ancient Thai glass bead; X-ray absorption near-edge structure; Extended X-ray absorption fine structure
SR-XRD and SR-FTIR study of the alteration of silver foils in medieval paintings by Nati Salvadó; Salvador Butí; Ana Labrador; Gianfelice Cinque; Hermann Emerich; Trinitat Pradell (3041-3052).
Altarpieces and polychrome carved wood from the fifteenth century AD usually exhibit golden and silvery areas by the application of a very thin foil of metal. The metal foils were normally protected from the atmosphere by a varnish or resin which maybe either preserved or absent. Moreover, they were glued to the background surface by adhesive substances (egg yolk, drying oil or animal glue). The high proportion of the glueing substances often renders the development of reaction compounds. With time, silver alters blacken or simply disappear completely. In this paper, we study the alterations to metal foils from a selection of fifteenth century artworks showing different glueing agents, organic coatings and several degrees of conservation of the organic coatings and metal leafs. The submillimetric layered structure and the high variability and low amount of most of the compounds present in the different layers, as well as their differing nature (organic and inorganic) make the use of micron-sensitive high-resolution techniques essential for their study. In particular, the high resolution, high brilliance and small footprint renders synchrotron radiation most adequate for their study. SR-XRD was performed to identify the reaction compounds formed in the different layers; μFTIR was used at to identify the silver protecting organic coatings, the metal foil glueing layers and the corresponding reaction compounds. The results obtained suggest that atmospheric corrosion is the dominant mechanism, and therefore that the degree of corrosion of the metal foils is mainly related to the conservation state of the protecting coatings. Figure Sampling point, MO image from surface of the sample and SEM image from polish cross-section of the sample
Keywords: Silver foil; Silver chloride; Silver sulphide; Cultural heritage; XRD; FTIR
Dealing with the identification of protein species in ancient amphorae by Sophie Dallongeville; Nicolas Garnier; Dario Bernal Casasola; Michel Bonifay; Christian Rolando; Caroline Tokarski (3053-3063).
This manuscript deals with the identification of protein residues in amphorae, including particularly identification of protein species. The work described was performed on fishes, the anchovy (Engraulis encrasicolus) and bonito (Sarda sarda) species frequently found in the Mediterranean area. Based on proteomic techniques, the analytical strategy was adapted to analysis of protein residues from tiny ceramic fragments. The major difficulty was to extract proteins and limit their hydrolysis during the sample preparation; consequently, multiple soft extraction techniques were evaluated. The most valuable results were obtained using a solution containing high amounts of denaturing agents, urea and thiourea, reducing agent, dithiothreitol, and detergent, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. The analysis using nano liquid chromatography–nano electrospray ionization double quadrupole time-of-flight mass spectrometry resulted in the identification of up to 200 proteins for the anchovy and bonito species, among which 73 peptides were found to be fish-specific. Because bonito and anchovy species are not documented and fully sequenced in genomic databases, the preliminary protein identification was realized via sequence homology to other fish sequenced species. Amino acid substitutions of peptides were assigned on the basis of the interpretation of tandem mass spectrometry spectra using de novo sequencing; these peptides, not reported up to now in databases, constitute species-specific markers. The method developed was finally applied to an archaeological sample replica impregnated with a mixture of fish tissue from both species; this experiment successfully led to the identification of 17 fish proteins, including 33 fish-specific peptides. This work shows that the analytical method developed has great potential for the identification of protein species in complex archaeological samples.
Keywords: Protein species; Archaeological ceramics; Proteomics; Tandem mass spectrometry; Amino acid substitution
HPLC–DAD–MS analysis of dyes identified in textiles from Mount Athos by Dimitrios Mantzouris; Ioannis Karapanagiotis; Lemonia Valianou; Costas Panayiotou (3065-3079).
Organic colorants contained in 30 textiles (16th to early 20th century) from the monastery of Simonos Petra (Mount Athos) have been investigated using high-performance liquid chromatography equipped with diode-array detection and mass spectrometry (HPLC–DAD–MS). The components of natural dyes identified in samples treated by the standard HCl dyestuff extraction method were: alizarin, apigenin, butein, carminic acid, chrysoeriol, dcII, dcIV, dcVII, ellagic acid, emodin, fisetin, flavokermesic acid, fustin, genistein, haematein derivative (Hae′), indigotin, indirubin, isoliquiritigenin, isorhamnetin, kaempferide, kaempferol, kermesic acid, luteolin, naringenin, purpurin, quercetin, rhamnazin, rhamnetin, sulfuretin, and type B and type C compounds (last two are markers for Caesalpinia trees). Early, semi-synthetic dyes, for example indigo carmine, fuchsin components, and rhodamine B were identified in objects dated late 19th to early 20th century. A dyestuff extraction method which involves use of TFA, instead of HCl, was applied to selected historical samples, showing that the mild method enables efficient extraction of weld (Reseda luteola L.) and dyer’s broom (Genista tinctoria L.) glycosides. The marker compound (Hae′) for logwood (Haematoxylum campechianum L.) identification after treatment with HCl was investigated by liquid chromatography coupled to mass spectrometry (LC–MS) in negative electrospray ionization (LC–MS-ESI−) mode. LC–MS in negative atmospheric pressure chemical ionization (LC–MS-APCI−) mode was used, probably for the first time, to investigate cochineal (Dactylopius coccus Costa) samples. Positive electrospray ionization (LC–MS-ESI+) mode was used for identification of fuchsin components. Detailed HPLC–DAD studies were performed on young fustic (Cotinus coggygria Scop.) and Persian berries (Rhamnus trees).
Keywords: Archeometry; Fine arts; HPLC; Natural products
Application of ATR-far-infrared spectroscopy to the analysis of natural resins by Silvia Prati; Giorgia Sciutto; Rocco Mazzeo; Cristian Torri; Daniele Fabbri (3081-3091).
This study proposes FTIR spectroscopy in the far-infrared region (FarIR) as an alternative method for the characterisation of natural resins. To this purpose, standards of natural resins belonging to four different categories (sesquiterpenic, i.e. elemi, shellac; diterpenic, i.e. colophony, Venice turpentine; diterpenic with polymerised components, i.e. copal, sandarac; triterpenic, i.e. mastic and dammar) used as paint varnishes have been analysed by FarIR spectroscopy in ATR mode. Discrimination between spectral data and repeatability of measurements have been magnified and verified using principal component analysis, in order to verify the effectiveness of the method in distinguishing the four resin categories. The same samples were analysed in the MidIR range, but the spectral differences between the different categories were not evident. Moreover, the method has been tested on historical samples from the painting “La Battaglia di Cialdiran” (sixteenth century) and from a gilded leather (seventeenth century). In the first case, FarIR spectroscopy allowed confirmation of the results obtained by analytical pyrolysis. In the latter, FarIR spectroscopy proved successfully, effective in the identification of the superficial resin layer that could not be detected with the bulk chromatographic analyses.
Keywords: Cultural heritage; ATR FIR spectroscopy; Natural resins; PCA
A multi-analytical approach for the identification of aloe as a colorant in oil–resin varnishes by Adriana Rizzo; Nobuko Shibayama; Daniel P. Kirby (3093-3107).
Aloe plants have been widely documented in artists’ treatises dating from the sixteenth to the nineteenth century as a source of colorant to achieve lustrous golden glazes on tin- and silver-foiled objects and warm-toned finishes on musical instruments, such as violins. Aloe extracts contain characteristic anthraquinone and phenolic components which impart a distinctive orange tone and fluorescence to mixtures containing them. Because of the low concentration of colorant in the coatings and its probable degradation by high temperature during manufacture, the identification of aloe in heated oil–resin mixtures represents an analytical challenge. For this reason, the possible presence of aloe in glazes and coatings has been largely overlooked. This paper describes various analytical approaches to the identification of aloe in historic samples, from comparison with results obtained from reference standards and mock-up samples. Complementary analytical techniques including thermally assisted hydrolysis and methylation–gas chromatography–mass spectrometry, high-performance liquid chromatography, laser desorption–mass spectrometry, matrix-assisted laser desorption-ionization-mass spectrometry and surface-enhanced Raman scattering were used. Different chemical markers were identified by the individual methods and the advantages and limitations of each technique for the identification of aloe in oil–resin varnishes are discussed.
Keywords: Aloe; Varnish; THM-GCMS; HPLC; SERS; LDMS; MALDI
Elemental 2D imaging of paintings with a mobile EDXRF system by François-Philippe Hocquet; Helena Calvo del Castillo; Ariadna Cervera Xicotencatl; Catherine Bourgeois; Cécile Oger; André Marchal; Mathieu Clar; Saïd Rakkaa; Edith Micha; David Strivay (3109-3116).
Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied. X-ray radiography and infrared reflectography as well as UV photography are some of the most applied techniques. The study of works of art usually requires these techniques to be non-invasive. Furthermore, they are frequently required to perform in situ analysis. A few years ago, our laboratory developed a mobile energy-dispersive X-ray fluorescence and UV–vis–NIR coupled spectrometer, especially designed for fieldwork studies, where all three techniques can be applied strictly at the same site of analysis. Recent developments on a new positioning system have now allowed us to perform 2D elemental mappings with our equipment, which is especially well adapted to painting analysis. The system control is carried out entirely through a laptop computer running a dedicated homemade software. The positioning is achieved by means of a CCD camera embedded in the system and controlled via a Wi-Fi connection through the computer. The data acquisition system, which is made through a homemade multichannel pulse height analyzer, being also managed via the software mentioned above, goes through an Ethernet connection. We will present here the new developments of the system and an example of in situ 2D elemental mapping applied on an anonymous oil painting on wood panel. The discovery of a hidden painting under this oil painting makes it a good choice for a first example of 2D large scan with a mobile instrument. Figure Portable X-Ray Fluorescence system developed by the Centre Européen d'Archéométrie for elemental 2D mapping
Keywords: X-ray spectroscopy; Archeometry/fine arts; Spectroscopy/instrumentation; Paintings
Unilateral NMR, 13C CPMAS NMR spectroscopy and micro-analytical techniques for studying the materials and state of conservation of an ancient Egyptian wooden sarcophagus by Noemi Proietti; Federica Presciutti; Valeria Di Tullio; Brenda Doherty; Anna Maria Marinelli; Barbara Provinciali; Nicola Macchioni; Donatella Capitani; Costanza Miliani (3117-3131).
A multi-technique approach was employed to study a decorated Egyptian wooden sarcophagus (XXV–XXVI dynasty, Third Intermediate Period), belonging to the Museo del Vicino Oriente of the Sapienza University of Rome. Portable non-invasive unilateral NMR was applied to evaluate the conservation state of the sarcophagus. Moreover, using unilateral NMR, a non-invasive analytical protocol was established to detect the presence of organic substances on the surface and/or embedded in the wooden matrix. This protocol allowed for an educated sampling campaign aimed at further investigating the state of degradation of the wood and the presence of organic substances by 13C cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The composition of the painted layer was analysed by optical microscopy (OM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), Raman and surface enhanced (resonance) Raman spectroscopy (SERS/SERRS), infrared and GC–MS techniques, evidencing original components such as clay minerals, Egyptian green, indigo, natural gums, and also highlighting restoration pigments and alteration compounds. The identification of the wood, of great value for the reconstruction of the history of the artwork, was achieved by means of optical microscopy.
Keywords: Unilateral NMR; 13C CPMAS spectroscopy; SERS; Wooden sarcophagus; Egyptian green
Multivariate chemical mapping of pigments and binders in easel painting cross-sections by micro IR reflection spectroscopy by Francesca Rosi; Arianna Federici; Brunetto G. Brunetti; Antonio Sgamellotti; Sergio Clementi; Costanza Miliani (3133-3145).
Paintings are composed of superimposed layers of inorganic and organic materials (pigments and binders). Knowledge of the stratigraphic sequence of these heterogeneous layers is fundamental for understanding the artist’s painting technique and for conservation issues. In this study, micro-IR mapping experiments in reflection mode have been carried out on cross-sections taken from simulations of ancient easel paintings. The objective was to locate both organic binders and inorganic pigments. Chemical maps have been re-constructed using the common approach based on the integration of specific infrared bands. However, owing to the complexity of painting materials, this approach is not always applicable when dealing with broad and superimposed spectral features and with reststrahlen or derivative-like bands resulting from acquisition in reflection mode. To overcome these limitations, principal-component analysis has been successfully used for the re-construction of the image, extracting the relevant information from the complex full spectral data sets and obtaining reliable chemical distributions of the stratigraphy materials. Different pigment–binder combinations have been evaluated in order to understand limitations and strengths of the approach. Finally, the method has been applied for stratigraphic characterization of a cross-section from a 17th century wooden sculpture identifying both the original paint layer and the several overpaintings constituting the complex stratigraphy. Figure a) OM image of an easel painting cross-section with the grid indicating the IR mapped area; b) t1 vs. t2 score plot including the color bar referred to the score values along each components; c) t2-score map; d) p1 and p2 profiles from PCA (labels: Gy-gypsum, L-lipid, I-amide I, II-amide II, U-ultramarine blue)
Keywords: IR reflection; Stratigraphy; PCA; Score-map; Painting material distribution
Combined non-destructive XRF and SR-XAS study of archaeological artefacts by Fabrizio Bardelli; Germana Barone; Vincenza Crupi; Francesca Longo; Domenico Majolino; Paolo Mazzoleni; Valentina Venuti (3147-3153).
We report on a non-destructive study of Sicilian ceramic fragments of cultural heritage interest, classified as “proto-majolica” pottery and dating back to the twelfth to thirteen centuries AD. The analytical approach used is based on the employment of two totally non-invasive spectroscopic techniques: X-ray fluorescence (XRF), using a portable energy-dispersive XRF analyser, and X-ray absorption spectroscopy, using synchrotron radiation as a probe (SR-XAS). XRF measurements allowed us to collect elemental and spatially resolved information on major and minor constituents of the decorated coating of archaeological pottery fragments, so providing preliminary results on the main components characterizing the surface. In particular, we assigned to Fe and Mn the role of key elements of the colouring agent. With the aim of obtaining more detailed information, we performed SR-XAS measurements at the Fe and Mn K-edges at the Italian BM08 beamline at the European Synchrotron Radiation Facility (Grenoble, France). The experimental data were analysed by applying principal component analysis and least-squares fitting to the near-edge part of the spectra (X-ray absorption near-edge structure) to determine the samples’ speciation. From the overall results, umber, a class of brownish pigments characterized by a mixture of hydrated iron and manganese oxides, has been ascribed as a pigmenting agent. Figure Fe K-edge XANES spectra of selected proto-majolica samples and reference compounds (FeO, Fe3O4, Fe2O3, Fe+SiO2). D pigmented, L not pigmented.
Keywords: X-ray fluorescence; X-ray absorption spectroscopy; Non-destructive methods; Pigments
Eighth Polish Conference on Analytical Chemistry by Paweł Kościelniak (3155-3156).
is a professor at both Jagiellonian University and the Institute of Forensic Research, Kraków, Poland. He is the head of the Department of Analytical Chemistry and the Laboratory of Forensic Chemistry (Jagiellonian University). His research interest is in development of new analytical methods and procedures in flow analysis and forensic chemistry with special attention to fundamental analytical issues such as calibration, interference effects, digestion, preconcentration, and separation. He is involved in designing original flow devices dedicated to various analytical purposes. He is also focused on miniaturization of flow systems and their adaptation to clinical and forensic analysis. Paweł Kościelniak has authored about 170 publications related to analytical chemistry and is a member of the Polish Committee of Analytical Chemistry of the Polish Academy of Sciences.
Nucleic acid-based fluorescent probes and their analytical potential by Bernard Juskowiak (3157-3176).
It is well known that nucleic acids play an essential role in living organisms because they store and transmit genetic information and use that information to direct the synthesis of proteins. However, less is known about the ability of nucleic acids to bind specific ligands and the application of oligonucleotides as molecular probes or biosensors. Oligonucleotide probes are single-stranded nucleic acid fragments that can be tailored to have high specificity and affinity for different targets including nucleic acids, proteins, small molecules, and ions. One can divide oligonucleotide-based probes into two main categories: hybridization probes that are based on the formation of complementary base-pairs, and aptamer probes that exploit selective recognition of nonnucleic acid analytes and may be compared with immunosensors. Design and construction of hybridization and aptamer probes are similar. Typically, oligonucleotide (DNA, RNA) with predefined base sequence and length is modified by covalent attachment of reporter groups (one or more fluorophores in fluorescence-based probes). The fluorescent labels act as transducers that transform biorecognition (hybridization, ligand binding) into a fluorescence signal. Fluorescent labels have several advantages, for example high sensitivity and multiple transduction approaches (fluorescence quenching or enhancement, fluorescence anisotropy, fluorescence lifetime, fluorescence resonance energy transfer (FRET), and excimer-monomer light switching). These multiple signaling options combined with the design flexibility of the recognition element (DNA, RNA, PNA, LNA) and various labeling strategies contribute to development of numerous selective and sensitive bioassays. This review covers fundamentals of the design and engineering of oligonucleotide probes, describes typical construction approaches, and discusses examples of probes used both in hybridization studies and in aptamer-based assays. Figure Hybridization with a nucleic acid target or affinity interactions with a nonnucleic acid target generate changes in the fluorescence characteristics of a nucleic acid-based fluorescent probe
Keywords: Bioanalytical methods; Bioassays; Biosensors; Chemical sensors; Fluorescence/luminescence; Nucleic acids (DNA, RNA)
Cuticular lipids of insects as potential biofungicides: methods of lipid composition analysis by Marek Gołębiowski; Mieczysława I. Boguś; Monika Paszkiewicz; Piotr Stepnowski (3177-3191).
The main function of cuticular lipids in insects is the restriction of water transpiration through the surface. Lipids are involved in various types of chemical communication between species and reduce the penetration of insecticides, chemicals, and toxins and they also provide protection from attack by microorganisms, parasitic insects, and predators. Hydrocarbons, which include straight-chain saturated, unsaturated, and methyl-branched hydrocarbons, predominate in the cuticular lipids of most insect species; fatty acids, alcohols, esters, ketones, aldehydes, as well as trace amounts of epoxides, ethers, oxoaldehydes, diols, and triacylglycerols have also been identified. Analyses of cuticular lipids are chemically relatively straightforward, and methods for their extraction should be simple. Classically, extraction has relied mainly on application of apolar solvents to the entire insect body. Recently, several alternative methods have been employed to overcome some of the shortcomings of solvent extraction. These include the use of solid-phase microextraction (SPME) fibers to extract hydrocarbons from the headspace of heated samples, SPME to sample live individuals, and a less expensive method (utilized for social wasps), which consists of the collection of cuticular lipids by means of small pieces of cotton rubbed on the body of the insect. Both classical and recently developed extraction methods are reviewed in this work. The separation and analysis of the insect cuticular lipids were performed by column chromatography, thin-layer chromatography (TLC), high performance liquid chromatography with a laser light scattering detector (HPLC-LLSD), gas chromatography (GC), and GC–mass spectrometry (MS). The strategy of lipid analysis with the use of chromatographic techniques was as follows: extraction of analytes from biological material, lipid class separation by TLC, column chromatography, HPLC-LLSD, derivatization, and final determination by GC, GC-MS, matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) MS, and liquid chromatography–mass spectrometry (LC-MS).
Keywords: Cuticular lipids of insects; High-performance liquid chromatography with a laser light scattering detector; Gas chromatography; Gas chromatography–mass spectrometry
Chromatographic methods and techniques used in studies of coals, their progenitors and coal-derived materials by Valentina Zubkova (3193-3209).
The use of chromatography in studies of coals, their progenitors and coal-related products was reviewed. The specificity of the coal structure was discussed. The use of extraction in preparing study samples was discussed paying special attention to the occurrence of undesirable phenomena such as aggregation of coal derivate molecules, resulting from the formation of their dimers and trimers, and degradation of polar solvents at temperatures above 350 °C. The following ways of fractionating samples of coal materials were considered: thermal, solvent, column with the use of preparative size exclusive chromatography and preparative thin layer chromatography as well as membrane separation. The use of chromatography coupled with experimental techniques such as mass spectrometry, infrared spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and pyrolysis was analysed. Figure Extraction scheme of bituminous coal with macromolecular network structure
Keywords: Coal structure; Extraction; Fractionation; Gas chromatography; Liquid chromatography
Analysis of isoflavones and flavonoids in human urine by UHPLC by Irena Baranowska; Sylwia Magiera (3211-3219).
A rapid, ultra high-performance liquid chromatographic (UHPLC) method has been developed and validated for simultaneous identification and analysis of the isoflavones genistein, daidzein, glycitin, puerarin, and biochanin A, and the flavonoids (±)-catechin, (−)-epicatechin, rutin, hesperidin, neohesperidin, quercitrin, and hesperetin in human urine. Urine samples were incubated with β-glucuronidase/sulfatase. UHPLC was performed with a Hypersil Gold (50 × 2.1 mm, 1.9 μm) analytical column. Elution was with a gradient prepared from aqueous trifluoroacetic acid (0.05%) and acetonitrile. UV detection was performed at 254 and 280 nm. The calibration curves were indicative of good linearity (r 2 ≥ 0.9992) in the range of interest for each analyte. LODs ranged between 15.4 and 107.0 ng mL−1 and 3.9 and 20.4 ng mL−1 for flavonoids and isoflavones, respectively. Intra-day and inter-day precision (C.V., %) was less than 3.9% and 3.8%, respectively, and accuracy was between 0.03% and 5.0%. Recovery was 70.35–96.58%. The method is very rapid, simple, and reliable, and suitable for pharmacokinetic analysis. It can be routinely used for simultaneous determination of these five isoflavones and seven flavonoids in human urine. The method can also be applied to studies after administration of pharmaceutical preparations containing isoflavones and flavonoids to humans.
Keywords: Isoflavones; Flavonoids; UHPLC; Pharmacokinetics
Application of spectroscopic techniques: ICP-OES, LA-ICP-MS and chemometric methods for studying the relationships between trace elements in clinical samples from patients with atherosclerosis obliterans by A. Hanć; I. Komorowicz; M. Iskra; W. Majewski; D. Barałkiewicz (3221-3231).
The study was aimed to evaluate the influence of the vascular disease, atherosclerotic obliterans (AO), on the location and concentration of elements in the arterial wall and serum. Use of a modern method for studying element’s concentration and distribution in samples of clinical material, i.e. laser ablation inductively coupled plasma mass spectrometry, is presented. Elements are not equally distributed between the inner (intima) and the outer (media + adventitia) layer of the arterial wall. Among the studied elements, calcium was found to have an unquestionable role in the calcification of the wall. Increased concentration of calcium found in the inner part of the atherosclerotic arterial wall and in the plaque, as compared to the control arterial wall samples, demonstrates the unquestionable role of this element in the calcification of the wall observed in AO. Applied chemometric methods were useful for demonstrating the differences in the element’s concentration in blood serum and the arterial wall samples between AO and the control group. Figure Image of the ruptured atherosclerotic plaque done while surgery
Keywords: Trace element detection; ICP-OES; LA-ICP-MS; Chemometric methods; Clinical samples; Atherosclerosis obliterans (AO)
Microwave-assisted hydrolysis and extraction of tricyclic antidepressants from human hair by Renata Wietecha-Posłuszny; Aneta Garbacik; Michał Woźniakiewicz; Paweł Kościelniak (3233-3240).
The objective of this research was to develop, optimize, and validate a modern, rapid method of preparation of human hair samples, using microwave irradiation, for analysis of eight tricyclic antidepressants (TCADs): nordoxepin, nortriptyline, imipramine, amitriptyline, doxepin, desipramine, clomipramine, and norclomipramine. It was based on simultaneous alkaline hair microwave-assisted hydrolysis and microwave-assisted extraction (MAH–MAE). Extracts were analyzed by high-performance liquid chromatography with diode-array detection (HPLC–DAD). A mixture of n-hexane and isoamyl alcohol (99:1, v/v) was used as extraction solvent and the process was performed at 60°C. Application of 1.0 mol L−1 NaOH and microwave irradiation for 40 min were found to be optimum for hair samples. Limits of detection ranged from 0.3 to 1.2 μg g−1 and LOQ from 0.9 to 4.0 μg g−1 for the different drugs. This enabled us to quantify them in hair samples within average therapeutic concentration ranges.
Keywords: Tricyclic antidepressants; Hair analysis; Microwave-assisted hydrolysis; Microwave-assisted extraction
Novel methodology for the extraction and identification of natural dyestuffs in historical textiles by HPLC–UV–Vis–ESI MS. Case study: chasubles from the Wawel Cathedral collection by Katarzyna Lech; Maciej Jarosz (3241-3251).
High-performance liquid chromatography coupled with spectrophotometric and electrospray mass spectrometric detection (HPLC–UV–Vis–ESI MS) was used for characterization of natural dyes present in historical art works. The gradient program was developed for identification of 29 colorants of various polarities. Dual detection system (UV–Vis and ESI MS) allowed differentiation of all compounds, even if they were not completely separated. This enabled examination of more color compounds over a substantially shorter time in comparison with previously recommended methods. Moreover, for extraction of colorants from historical textiles a two-step sequential procedure was proposed, excluding evaporation used in earlier procedures. The developed method was successfully applied to identification of indigotin, carminic, kermesic, flavokermesic, dcII, dcIV, dcVII, and ellagic acids as well as luteolin, apigenin, and genistein in red, violet, and green fibers taken from three selected historical chasubles which belong to the collection of the Wawel Cathedral treasury (Cracow, Poland). Italian textiles from the fifteenth and sixteenth centuries, of which chasubles were made, were dyed with a limited number of dyestuffs, consistently used for all batches of fabrics. The obtained results also allowed confirmation of the structure of the so-called “dcII” component of cochineal as a C-glucose derivative of flavokermesic acid.
Keywords: Archaeometry; dcII; Extraction; HPLC–UV–Vis–ESI MS; Natural dyestuffs; Polish cochineal
A new procedure for the determination of distillation temperature distribution of high-boiling petroleum products and fractions by Grzegorz Boczkaj; Andrzej Przyjazny; Marian Kamiński (3253-3260).
The distribution of distillation temperatures of liquid and semi-fluid products, including petroleum fractions and products, is an important process and practical parameter. It provides information on properties of crude oil and content of particular fractions, classified on the basis of their boiling points, as well as the optimum conditions of atmospheric or vacuum distillation. At present, the distribution of distillation temperatures is often investigated by simulated distillation (SIMDIS) using capillary gas chromatography (CGC) with a short capillary column with polydimethylsiloxane as the stationary phase. This paper presents the results of investigations on the possibility of replacing currently used CGC columns for SIMDIS with a deactivated fused silica capillary tube without any stationary phase. The SIMDIS technique making use of such an empty fused silica column allows a considerable lowering of elution temperature of the analytes, which results in a decrease of the final oven temperature while ensuring a complete separation of the mixture. This eliminates the possibility of decomposition of less thermally stable mixture components and bleeding of the stationary phase which would result in an increase of the detector signal. It also improves the stability of the baseline, which is especially important in the determination of the end point of elution, which is the basis for finding the final temperature of distillation. This is the key parameter for the safety process of hydrocracking, where an excessively high final temperature of distillation of a batch can result in serious damage to an expensive catalyst bed. This paper compares the distribution of distillation temperatures of the fraction from vacuum distillation of petroleum obtained using SIMDIS with that obtained by the proposed procedure. A good agreement between the two procedures was observed. In addition, typical values of elution temperatures of n-paraffin standards obtained by the two procedures were compared. Finally, the agreement between boiling points of polar compounds determined from their retention times and actual boiling points was investigated. Figure SIMDIS and EC-GC distillation curves of fractions B, C, and D
Keywords: SIMDIS; Gas chromatography; GC; Simulated distillation; Distillation temperature distribution; Analytics of petroleum products
Oil refinery dusts: morphological and size analysis by TEM by Przemysław Sielicki; Helena Janik; Agnieszka Guzman; Mieczysław Broniszewski; Jacek Namieśnik (3261-3270).
The objectives of this work were to develop a means of sampling atmospheric dusts on the premises of an oil refinery for electron microscopic study to carry out preliminary morphological analyses and to compare these dusts with those collected at sites beyond the refinery limits. Carbon and collodion membranes were used as a support for collection of dust particles straight on transmission electron microscopy (TEM) grids. Micrographs of the dust particles were taken at magnifications from ×4,000 to ×80,000 with a Tesla BS500 transmission electron microscope. Four parameters were defined on the basis of the micrographs: surface area, Feret diameter, circumference, and shape coefficient. The micrographs and literature data were used to classify the atmospheric dusts into six groups: particles with an irregular shape and rounded edges; particles with an irregular shape and sharp edges; soot and its aggregates; spherical particles; singly occurring, ultrafine dust particles; and particles not allocated to any of the previous five groups. The types of dusts found in all the samples were similar, although differences did exist between the various morphological parameters. Dust particles with the largest Feret diameter were present in sample 3 (mean, 0.739 μm)—these were collected near the refinery's effluent treatment plant. The particles with the smallest diameter were found in the sample that had been intended to be a reference sample for the remaining results (mean, 0.326 μm). The dust particles collected in the refinery had larger mean Feret diameters, even 100% larger, than those collected beyond it. Particles with diameters from 0.1 to 0.2 μm made up the most numerous group in all the samples collected in the refinery.
Keywords: Aerosols/particulates; Electron/ion microprobe; Software; Air/gases; Industrial hygiene; Sampling
Vibrational spectroscopy to study degradation of natural dyes. Assessment of oxygen-free cassette for safe exposition of artefacts by Monika Koperska; Tomasz Łojewski; Joanna Łojewska (3271-3283).
An important issue connected with conservation chemistry is how to improve the storage and exposure conditions in order to suppress the fading and degradation of dyes and other components of paintings. Although the oxygen-free exposure cassettes are commonly known in museums, there is still lack of information in the literature about the effect of anoxic conditions on the degradation of dyes. This study is an attempt to start a database formation on the dyes degradation. Five commercial dyes (indigo, dragon’s blood, curcumin, madder, carminic acid) were submitted to accelerated ageing by exposure to intensive light in the visible range in both oxygen-free (anoxia) and -rich conditions. Degradation of the samples was investigated by several analytical techniques (attenuated total reflectance infrared spectroscopy, Raman spectroscopy, reflectance UV–Vis spectroscopy, X-ray fluorescence spectroscopy and optical microscopy). The conclusions are based on the estimators (derived from the determination of colour differences from Vis spectra and from the changes in FTIR and Raman vibrational bands intensity). According to them, only indigo, dragon’s blood and curcumin show greater stability in anoxic conditions in comparison with oxygen-rich ones while madder, carminic acid undergo greater degradation. Figure
Keywords: Vibrational spectroscopy; X-ray fluorescence; Natural dyes; Alizarin; Madder; Indigo; Curcumin; Dragon blood; Degradation; Anoxia
Nondestructive analysis of single crystals of selenide spinels by X-ray spectrometry techniques by E. Malicka; R. Sitko; B. Zawisza; J. Heimann; D. Kajewski; A. Kita (3285-3292).
The paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed by means of X-ray spectrometry techniques: micro-X-ray fluorescence spectrometry (μ-XRF), energy-dispersive electron probe microanalysis (ED-EPMA), and X-ray photoelectron spectroscopy (XPS). The capability of the X-ray spectroscopy techniques in elemental analysis is demonstrated with the single crystals of selenide spinels of the general formula M x N y Cr z Se4 (M+2 and N+3 are, for example, Zn+2, V+3, Ga+3, Cd+2, In+3, and Sb+3). The results of the nondestructive analyses (μ-XRF, ED-EPMA, and XPS) are compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) and wavelength-dispersive X-ray spectrometry (WDXRF) following sample digestion. The present study shows satisfactory agreement between the results of μ-XRF analysis performed using the standardless fundamental parameter method and the results obtained with the WDXRF and ICP-OES analyses. If the measured single crystal is precisely positioned, the difference between μ-XRF and wet analysis (WDXRF and ICP-OES) does not exceed 5% rel. The reliable results of ED-EPMA can be obtained only if the measured area is sufficiently large, i.e., of 200 × 300 μm. Even if this condition is fulfilled, the relative difference between the ED-EPMA and the wet analysis may reach 10% rel. In case of the XPS analysis, the accuracy of results depends on the proper preparation of the sample surface. It should be free of contamination that can be obtained by scraping in situ in ultrahigh vacuum. The ion etching, commonly used for cleaning the surface, leads to preferential sputtering; therefore, the reliable results cannot be obtained. Figure The paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed by means of X-ray spectrometry techniques: micro-XRF, ED-EPMA and XPS.
Keywords: Micro-XRF; EPMA; XPS; Selenide spinel; Nondestructive analysis; Chalcogenide compounds
Hemoglobin determination with paired emitter detector diode by Elżbieta Mieczkowska; Robert Koncki; Łukasz Tymecki (3293-3297).
Two ordinary green light-emitting diodes used as light emitter and detector coupled with simple voltmeter form a complete, cost-effective prototype of a photometric hemoglobinometer. The device has been optimized for cuvette assays of total hemoglobin (Hb) in diluted blood using three different chemical methods recommended for the needs of clinical analysis (namely Drabkin, lauryl sulfate, and dithionite methods). The utility of developed device for real analytics has been validated by the assays of total Hb content in human blood. The results of analysis are fully compatible with those obtained using clinically recommended method and clinical analyzer.
Keywords: Hemoglobin; Blood; Photometry; Paired emitter detector diode
Application of headspace solid-phase microextraction followed by gas chromatography–mass spectrometry to determine short-chain alkane monocarboxylic acids in aqueous samples by Anna Banel; Marta Wasielewska; Bogdan Zygmunt (3299-3303).
In this study, a procedure was developed to determine short-chain alkane monocarboxylic acids (SCMAs) in aqueous samples using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography (GC) coupled with mass spectrometry (MS). A Stabilwax-DA capillary column (30 m × 0.32-mm inner diameter, 0.50-μm film thickness) was used for GC separation and a 60-μm poly(ethylene glycol) fiber was used to isolate SCMAs from water and introduce them into the gas chromatograph. Parameters of HS-SPME, analyte desorption, and GC-MS analysis were selected and an analytical procedure was proposed. Limits of quantitation were on the order of about 0.2 mg L-1. As an example of the application of the procedure, SCAMs were determined in municipal wastewater at different steps of treatment.
Keywords: Short-chain alkane monocarboxylic acids; Headspace; Solid-phase microextraction; Gas chromatography–mass spectrometry; Wastewater