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Analytical and Bioanalytical Chemistry (v.402, #4)

An overview on education of analytical chemistry in Japan by Hitoshi Watarai (pp. 1399-1404).

is Professor Emeritus of Osaka University and received a PhD in Science (1978) from Tohoku University. From 1993 to 2010 he was a Professor in the Department of Chemistry at Osaka University. He retired in 2010 and is now an Invited Professor at the Institute for NanoScience Design at Osaka University. He received the Divisional Award of the Chemical Society of Japan in 2000, and the Analytical Chemistry Award from The Japan Society for Analytical Chemistry on 2003.

CE in the Biotechnology & Pharmaceutical Industries—CE Pharm 2011 by Carolin Huhn (pp. 1405-1406).

Eirelec 2011: electrochemistry–the future? by Stefan Bergner (pp. 1407-1408).

Ajit Sadana and Neeti Sadana: Handbook of biosensors and biosensor kinetics by Anne W. Kusterbeck (pp. 1409-1410).

Analytical techniques in art, archaeology and conservation science by Oliver Hahn (pp. 1411-1411).

is head of the research group “Analysis of Cultural Assets” at the BAM Bundesanstalt für Materialforschung und –prüfung in Berlin, Germany. His special fields of interest include the non-destructive investigation of art objects with different analytical techniques (XRF, X-ray absorption near-edge structure, Fourier transform IR and visible spectroscopy) as well as the characterization of environmental conditions in museums and archives.

Studying pigments on painted plaster in Minoan, Roman and Early Byzantine Crete. A multi-analytical technique approach by Polly Westlake; Panayiotis Siozos; Aggelos Philippidis; Chryssa Apostolaki; Brendan Derham; Agni Terlixi; Vasilios Perdikatsis; Richard Jones; Demetrios Anglos (pp. 1413-1432).

Wall paintings spanning two millennia of Cretan painting history and technology were analysed in an effort to determine similarities and evolutions of painting materials and technology. A multi-technique approach was employed that combined the use of (a) laser-induced breakdown spectroscopy (LIBS) and Raman microspectroscopy, based on mobile instrumentation, appropriate for rapid, routine-level object characterization, and (b) non-destructive X-ray diffractometry (XRD), performed directly on the wall painting fragment, which provides detailed information on the minerals constituting the paint. Elemental analysis data obtained through LIBS were compared with molecular and crystal structure information from Raman spectroscopy and XRD. Cross-sections from selected samples were also investigated by means of optical microscopy and scanning electron microscopy coupled to micro-probe analysis and X-ray mapping that enabled identification of several mineral components of the paint confirming the results of the XRD analysis. In parallel, replica wall paintings, created with known pigments and binding media for reference purposes, were examined with optical microscopy and stain tested for organic materials. The overall study shows that the LIBS and Raman techniques offer key advantages, such as instrument mobility and speed of data collection and interpretation that are particularly important when dealing with on-site investigations. Thus, they are capable of providing important compositional information in an effective manner that enables quick surveying of wall paintings and permit targeted sample selection for further analysis by advanced laboratory techniques. Figure Optical microscopy image of painted plaster from the Minoan Palace of Knossos, Crete, showing blue paint composed of Egyptian Blue (Cuprorivaite) and Mg-riebeckite. Clockwise are shown a LIBS spectrum showing the presence of Cu along with Ca, Al and Fe, in the blue paint; b Fluorescence emission spectrum with the characteristic emission of Egyptian Blue at around 900 nm and c X-ray diffractogram confirming the presence of Cuprorivaite and Mg-riebeckite

Keywords: Archaeological pigments; Wall paintings; Analysis; LIBS; Raman; XRD; SEM-EDX

Laser-induced fluorescence and FT-Raman spectroscopy for characterizing patinas on stone substrates by M. Oujja; C. Vázquez-Calvo; M. Sanz; M. Álvarez de Buergo; R. Fort; M. Castillejo (pp. 1433-1441).

This article reports on a compositional investigation of stone patinas: thin colored layers applied for protective and/or aesthetic purposes on architectural or sculptural substrates of cultural heritage. The analysis and classification of patinas provide important information of historic and artistic interest, as their composition reflects local practices, the availabilities of different materials, and the development of technological knowledge during specific historical periods. Model patinas fabricated according to traditional procedures and applied onto limestone, and a historic patina sample from the main façade of the San Blas Monastery in Lerma (a village in the province of Burgos, Spain), were analyzed by laser-induced fluorescence and Fourier transform Raman spectroscopy. The results obtained demonstrate the ability of these two analytical techniques to identify the key components of each formulation and those of the reaction products which result from the chemical and mineralogical transformations that occur during aging, as well as to provide information that can aid the classification of different types of patinas. Figure Cross section of model patina (left) and FT-Raman spectrum of historic patina from the façade of San Blas Monastery, Lerma, Burgos, Spain (right).

Keywords: Laser-induced fluorescence; FT-Raman spectroscopy; Patinas; Stone substrates

Multivariate classification of pigments and inks using combined Raman spectroscopy and LIBS by Marek Hoehse; Andrea Paul; Igor Gornushkin; Ulrich Panne (pp. 1443-1450).

The authenticity of objects and artifacts is often the focus of forensic analytic chemistry. In document fraud cases, the most important objective is to determine the origin of a particular ink. Here, we introduce a new approach which utilizes the combination of two analytical methods, namely Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS). The methods provide complementary information on both molecular and elemental composition of samples. The potential of this hyphenation of spectroscopic methods is demonstrated for ten blue and black ink samples on white paper. LIBS and Raman spectra from different inks were fused into a single data matrix, and the number of different groups of inks was determined through multivariate analysis, i.e., principal component analysis, soft independent modelling of class analogy, partial least-squares discriminant analysis, and support vector machine. In all cases, the results obtained with the combined LIBS and Raman spectra were found to be superior to those obtained with the individual Raman or LIBS data sets. Figure Combination of Raman spectroscopy and LIBS for improved classification of inks: score plot from PCA and experimental set-up

Keywords: Pigments; Raman; LIBS; Chemometrics

Micro-Raman study of copper hydroxychlorides and other corrosion products of bronze samples mimicking archaeological coins by Giulia Bertolotti; Danilo Bersani; Pier Paolo Lottici; Marcella Alesiani; Thomas Malcherek; Jochen Schlüter (pp. 1451-1457).

Three bronze samples created by CNR-ISMN (National Research Council—Institute of Nanostructured Materials) to be similar to Punic and Roman coins found in Tharros (OR, Sardinia, Italy) were studied to identify the corrosion products on their surfaces and to evaluate the reliability of the reproduction process. Micro-Raman spectroscopy was chosen to investigate the corroded surfaces because it is a non-destructive technique, it has high spatial resolution, and it gives the opportunity to discriminate between polymorphs and to correlate colour and chemical composition. A significant amount of green copper hydroxychlorides (Cu₂(OH)₃Cl) was detected on all the coins. Their discrimination by Raman spectroscopy was challenging because the literature on the topic is currently confusing. Thus, it was necessary to determine the characteristic peaks of atacamite, clinoatacamite, and the recently discovered anatacamite by acquiring Raman spectra of comparable natural mineral samples. Clinoatacamite, with different degrees of order in its structure, was the major component identified on the three coins. The most widespread corrosion product, besides hydroxychlorides, was the red copper oxide cuprite (Cu₂O). Other corrosion products of the elements of the alloy (laurionite, plumbonacrite, zinc carbonate) and those resulting from burial in the soil (anatase, calcite, hematite) were also found. This study shows that identification of corrosion products, including discrimination of copper hydroxychlorides, could be accomplished by micro-Raman on valuable objects, for example archaeological findings or works of art, avoiding any damage because of extraction of samples or the use of a destructive analytical technique.

Keywords: Raman spectroscopy; Copper hydroxychlorides; Coins; Bronze; Corrosion products; Archaeological metals

Non-destructive dating of fiber-based gelatin silver prints using near-infrared spectroscopy and multivariate analysis by Ana Martins; Lee Ann Daffner; Ann Fenech; Christopher McGlinchey; Matija Strlič (pp. 1459-1469).

An innovative approach to date fiber-based gelatin silver prints using near-infrared spectroscopy (NIR) and multivariate analysis is presented. NIR spectra were acquired for 152 film stills printed in the USA between 1914 and 1986, and partial least square (PLS) analysis was used to correlate the spectra with the year the photographs were printed. Principal component analysis and spectral interpretation helped clarify the underlying correlation between the print date and the composition and ageing of the photographic papers. The method was successfully validated with an independent set of 66 film stills printed in the USA, and a prediction error (root mean square error of prediction) of 6 years was achieved. The method was also tested on films stills printed in Germany and Russia, as well as amateur prints and photographs in the collection of the Museum of Modern Art. The prediction error was significantly larger, with the exception of the amateur prints, due to differences in the composition and/or properties of the papers depending on their geographical origin and purpose as confirmed by discriminant analysis. Figure PLS-NIR model to predict the print date of fiber based gelatin silver photographs

Keywords: Photographic paper; Cultural heritage; Dating method; Near infrared spectroscopy; Multivariate analysis

Possibilities of energy-resolved X-ray radiography for the investigation of paintings by Ana E. Cabal Rodríguez; Diana Leyva Pernía; Olivier Schalm; Pierre J. M. Van Espen (pp. 1471-1480).

X-ray radiographic images of paintings often show little or no contrast. In order to increase the contrast in radiographic images we measured the X-ray spectrum of a low power X-ray tube, after passing through the painting, with a high energy-resolution SDD detector. To obtain images, the detector is collimated with a 400 μm diameter pinhole and the painting was moved through the beam in the x and y-direction using a dwell time of a few seconds per pixel. The data obtained consists of a data cube of, typically, 200 × 200 pixels and a 512-channel X-ray spectrum for each pixel, spanning the energy range from 0 to 40 keV. Having the absorbance spectrum available for each pixel, we are able, a posteriori, to produce images by edge subtraction for any given element. In this way high contrast, element-specific, images can be obtained. Because of the high energy-resolution a much simpler edge subtraction algorithm can be applied. We also used principal-component imaging to obtain, in a more automated way, images with high contrast. Some of these images can easily be attributed to specific elements. It turns out that preprocessing of the spectral data is crucial for the success of the multivariate image processing.

Keywords: Energy-resolved X-ray radiography; Multivariate imaging; Edge-subtraction imaging; Cultural heritage

Characterization of “oil on copper” paintings by energy dispersive X-ray fluorescence spectrometry by A. Pitarch; A. Ramón; A. Álvarez-Pérez; I. Queralt (pp. 1481-1492).

Energy dispersive X-ray fluorescence is a common analytical tool for layer thickness measurements in quality control processes in the coating industry, but there are scarce microanalytical applications in order to ascertain semi-quantitative or quantitative information of painted layers. “Oil on copper” painting becomes a suitable material to be analysed by means of X-ray fluorescence spectrometry, due to the metallic nature of substrate and the possibility of applying layered models as used in coating industry. The aim of this work is to study the suitability of a quantitative energy dispersive X-ray fluorescence methodology for the assessment of the areal distribution of pigments and the characterization of painting methods on such kind of pictorial artworks. The method was calibrated using standard reference materials: dried droplets of monoelemental standard solutions laid on a metallic plate of copper. As an example of application, we estimated pigment mass distribution of two “oil on copper” paintings from the sixteenth and eighteenth centuries. Pictorial layers have been complementarily analysed by X-ray diffraction. Apart of the supporting media made of copper or brass, we could identify two different superimposed layers: (a) a preparation layer mainly composed by white lead and (b) the pictorial layer of variable composition depending on the pigments used by the artist on small areas of the painting surface. The areal mass distribution of the different elements identified in the painting pigments (Ca, Cr, Mn, Fe, Zn, Cd, Hg and Pb) have been determined by elemental mapping of some parts of the artworks.

Keywords: Non destructive analysis; EDXRF; Pigment mass distribution; “Oil on copper”

Provenance studies on Dead Sea scrolls parchment by means of quantitative micro-XRF by Timo Wolff; Ira Rabin; Ioanna Mantouvalou; Birgit Kanngießer; Wolfgang Malzer; Emanuel Kindzorra; Oliver Hahn (pp. 1493-1503).

In this study, we address the question of the provenance and origin of the Dead Sea Scrolls manuscripts. A characteristic low ratio of chlorine to bromine, corresponding to that of the Dead Sea water, may serve as an indicator for local production. For this aim we developed a non-destructive procedure to determine the Cl/Br ratio in the parchment of these manuscripts. Micro-X-ray fluorescence (μ-XRF) measurements of a large number of parchment and leather fragments from the Dead Sea Scrolls were analyzed with a routine we developed based on fundamental parameter quantification. This routine takes into account the absorption of the collagen matrix and the influence of the different sample thicknesses. To calculate the representative Cl/Br ratio for each fragment, we investigated the lateral homogeneity and determined the total mass deposition using the intensity of the inelastically scattered, characteristic tube radiation. The distribution of the Cl/Br ratios thus obtained from the μ-XRF measurements make it possible to distinguish fragments whose origin lies within the Dead Sea region from those produced in other locations. Figure Quantitative mikro-XRF permits the determination of the Cl/Br-ratio in ancient Dead Sea scrolls parchment. The picture shows a fragment from the Genesis Apocryphon Scroll 1Q GenAp.(courtesy of Israel Museum)

Keywords: Fundamental parameter quantification; Samples of intermediated thickness; Chlorine to bromine ratio; Scatter peak evaluation; Dark matrix; Inorganic traces

The Egmont Master phenomenon: X-ray fluorescence spectrometric and paper studies for art history research by Georg Dietz; Thomas Ketelsen; Manfred Hoss; Olaf Simon; Carsten Wintermann; Timo Wolff; Ira Rabin; Oliver Hahn (pp. 1505-1515).

The aim of the research project “Typology of Dutch Drawing” was to establish an interdisciplinary approach for investigating heterogeneous drawing collections. To define a type common to a group of drawings, we determine elements that are common to them based on style and the use of identical materials. To that end, we investigated about 750 Dutch drawings from the sixteenth century at the Dresden Kupferstich-Kabinett using art historical and scientific methods. In this work, we present a detailed analysis of 30 drawings ascribed to the Egmont Master.

Keywords: Archeometry; Fine arts; Nondestructive testing; Paper analysis; X-ray fluorescence spectrometry (XRF); Reference materials

The Indian drawings of the poet Cesare Pascarella: non-destructive analyses and conservation treatments by Marina Bicchieri; Michela Monti; Giovanna Piantanida; Flavia Pinzari; Simonetta Iannuccelli; Silvia Sotgiu; Lorena Tireni (pp. 1517-1528).

The Italian dialect poet Cesare Pascarella travelled all around the world, noting down in notebooks his keen and caustic observations, and drawing sketches that are a visual reportage of his journeys. The sketches were mounted as a random collage over acidic cardboards that were exposed to direct sunlight in his studio. Their poor state of conservation is related to the use of modern paper: chemical instability of raw materials caused acidification and strong oxidation of the support, with intense yellowing of the surfaces and brittleness of the paper. To ensure future preservation of the drawings, chemical stabilisation with simultaneous alcoholic treatment by deacidification (calcium propionate) and reduction (borane tert-butylamine complex) appeared necessary. To verify its applicability, it was indispensible to characterise the support and identify the nature of all the graphic media. The use of Raman, Infrared, X-ray fluorescence spectroscopies and scanning electron microscopy coupled with X-ray microanalysis allowed us to clear the problems related to the different penetration depth of each analytical technique and the different responses of pigments/dyes to each spectroscopy. The palette, how it varied along the journeys, the different supports used and preparations were completely identified showing a choice of colours compatible with the reduction treatment. Figure Top: Drawing A12. Left: before chemical stabilisation and conservation treatment. Right: after chemical deacidification/reduction and the final conservation intervention. Bottom Left: SEM image of the paper composition of drawing A19. Bottom right: Raman spectra of the paper support of drawing B6 before and after the reduction treatment. On the top, the spectra without baseline correction; on the bottom, the spectrum after reduction is compared with a standard spectrum of pure cellulose paper that shows a perfect recovery of the original structure of the paper after the chemical treatment.

Keywords: Paper; Micro-Raman; ATR-FTIR; SEM-EDS; XRF; Reduction

Use of in situ and confocal Raman spectroscopy to study the nature and distribution of carotenoids in brown patinas from a deteriorated wall painting in Marcus Lucretius House (Pompeii) by M. Maguregui; U. Knuutinen; J. Trebolazabala; H. Morillas; K. Castro; I. Martinez-Arkarazo; J. M. Madariaga (pp. 1529-1539).

Colonisation of wall paintings by microorganisms and other organisms is a well-known problematic phenomenon. Besides taxonomic identification of the biodeteriogen, it is essential to evaluate the consequences of the colonisation, e.g., unsightly coloured patinas. This work proposes new methodology for characterisation of the nature of the main carotenoids and their distribution in brown stains or patinas of a deteriorated wall painting on the north wall of the atrium of Marcus Lucretius House (Pompeii, Italy). Characterisation of the brown patinas and surrounding areas (plaster and polychromy) from the wall painting started with in situ screening using, mainly, a portable Raman instrument with a handheld FTIR (DRIFTS sampling interface) in order to select the sampling areas suitable for further analysis in the laboratory. Two wall painting fragments were then analysed in the laboratory in two steps. First, microscopic observations (SEM and phase-contrast microscopy) were used to determine whether biodeteriogens were present in the samples. In a second step, confocal Raman microscopy (785 and 514 nm excitation lasers) was used to characterise the main biogenic compounds of the brown stains. Because of the resonance Raman effect (514 nm excitation laser), it was possible to obtain reliable Raman features to assign not only the nature of the main biogenic pigments (carotenoids) present in the stains, but also their spatial conformation. Moreover, Raman confocal applications, for example, Raman imaging and depth profiling were also used in a first attempt to determine the distribution of biosynthesised carotenoids in the stains, and to determine the thickness of the brown patinas.

Keywords: Bioimpacts; Bryopsida moss; Carotenoids; Resonance Raman spectroscopy; Raman chemical imaging; Raman depth profiling

Fungal bioleaching of mineral components in a twentieth-century illuminated parchment by F. Pinzari; P. Colaizzi; O. Maggi; A. M. Persiani; R. Schütz; I. Rabin (pp. 1541-1550).

In this work, we applied scanning electron microscopy (SEM), microanalysis and Raman spectroscopy to study the fungi inhabiting a richly illuminated parchment document and the damage induced by their activity. To that aim, we collected samples of fungal mycelium from the deteriorated areas on a removable adhesive tape specifically intended for lifting fungi without damaging the support. SEM analysis of the adhesive tape samples showed the co-occurrence of several species of fungi. One strain closely resembling Acremonium species was observed only in the tape micrographs but no agar cultures were obtained. Its fungal structures showed the production of abundant oxalates with an outstanding leaching of the calcium-based materials of parchment (typically manufactured with gypsum and lime). Needle-like crystals of calcium oxalate produced by the fungus forming a uniform and quite regular grid around conidial slimy heads were documented. As a result, the areas affected by moulds were weakened, stained and characterised by a powdery patina rich in calcium. Confocal μ-Raman confirmed the presence of oxalates while EDS showed the presence of calcium in crystals. We conclude that the defacement of the parchment was due to both collagenolytic activity, and to the biotransformation of calcium-based minerals by fungi.

Keywords: Parchment; Biodeterioration; SEM-EDS; Raman; Oxalates; Fungi

Solid-state and unilateral NMR study of deterioration of a Dead Sea Scroll fragment by A. Masic; M. R. Chierotti; R. Gobetto; G. Martra; I. Rabin; S. Coluccia (pp. 1551-1557).

Unilateral and solid-state nuclear magnetic resonance (NMR) analyses were performed on a parchment fragment of the Dead Sea Scroll (DSS). The analyzed sample belongs to the collection of non-inscribed and nontreated fragments of known archaeological provenance from the John Rylands University Library in Manchester. Therefore, it can be considered as original DSS material free from any contamination related to the post-discovery period. Considering the paramount significance of the DSS, noninvasive approaches and portable in situ nondestructive methods are of fundamental importance for the determination of composition, structure, and chemical–physical properties of the materials under study. NMR studies reveal low amounts of water content associated with very short proton relaxation times, T ₁, indicating a high level of deterioration of collagen molecules within scroll fragments. In addition, ¹³C cross-polarization magic-angle-spinning (CPMAS) NMR spectroscopy shows characteristic peaks of lipids whose presence we attribute to the production technology that did not involve liming. Extraction with chloroform led to the reduction of both lipid and protein signals in the ¹³C CPMAS spectrum indicating probable involvement of lipids in parchment degradation processes. NMR absorption and relaxation measurements provide nondestructive, discriminative, and sensitive tools for studying the deterioration effects on the organization and properties of water and collagen within ancient manuscripts. Fig The state of deterioration of a Dead Sea scroll fragment was studied by means of ¹H and ¹³C solid state NMR and proton T ₁ relaxation measurements

Keywords: Dead Sea Scrolls; Collagen deterioration; Solid-state NMR; Unilateral NMR

A study of degradation of historic parchment using small-angle X-ray scattering, synchrotron-IR and multivariate data analysis by Alenka Možir; Lee Gonzalez; Irena Kralj Cigić; Tim J. Wess; Ira Rabin; Oliver Hahn; Matija Strlič (pp. 1559-1566).

Parchment has been in use for thousands of years and has been used as the writing or drawing support for many important historic works. A variety of analytical techniques is currently used for routine assessment of the degree of denaturation of historic parchment; however, because parchment has a heterogeneous nature, analytical methods with high spatial resolution are desirable. In this work, the use of small-angle X-ray scattering (SAXS) and synchrotron-IR (SR-IR) was examined in conjunction with multivariate data analysis to study degradation of an extended set of historic parchment samples, and particularly to investigate the effect of lipids and the presence of iron gall ink on the degradation processes. In the data analysis, shrinkage temperature, lipid content, sample age, presence of ink and accelerated degradation were included. The analysis of loading factors in partial least-squares regression and principal component analyses based on SAXS, SR-IR and other analytical and descriptive data reveals the effect of lipid removal on diffraction patterns, and lipids are found to cause the degradation process in parchment to accelerate. The effect of iron gall ink is also evident, although the mechanism of ageing is different to that of natural ageing in the absence of ink. In addition, a historic parchment score from ca. 1750 is examined, demonstrating the significant effect of iron gall ink, and lipids and inorganic soiling on its increased degradation.

Keywords: Small-angle X-ray scattering; Multivariate data analysis; Degradation; Collagen; Lipids; Iron gall ink

UV ageing studies: evaluation of lightfastness declarations of commercial acrylic paints by Valentina Pintus; Shuya Wei; Manfred Schreiner (pp. 1567-1584).

The lightfastness declarations of several different commercial acrylic paints and different quality series were tested by artificial UV ageing. To evaluate their lightfastness declarations, three acrylic colours (cadmium red, ultramarine blue and chromium oxide green) from six companies (Lascaux, Liquitex, Lukas, Rembrandt, Schmincke, and Winsor & Newton) were analysed before and after UV exposure. Characterisation and identification of these materials were carried out with Py–GC/MS, FTIR–ATR analyses, and colour measurements. Particular attention was focused on the Py–GC/MS measurements and on comparison of the single-shot method for pyrolysis of polymers and the double-shot mode which enables a unique combination of pyrolysis methods for analysis of polymers and thermal desorption for documentation of the volatile compounds. Depending on the particular company and the specific value of the lightfastness declaration, different binding media (i.e. poly(EA/MMA), poly(nBA/MMA), and poly(2-EHA/MMA)), and fillers (i.e. kaolinite, calcium carbonate, barite, and talc) were characterised and identified by Py–GC/MS and FTIR–ATR analyses. After UV exposure, several alteration processes with consequent formation of volatile compounds or new products were observed by both techniques, especially for the blue paints. In particular, the double-shot mode of Py–GC/MS enabled the detection of oxidation products, which could not be detected with the single-shot mode. Comparison of the lightfastness declarations for each of the blue, green, and red paints and the noted alterations broadly agreed for most of the paints.

Keywords: Py–GC/MS; FTIR–ATR; Double-shot technique; Acrylic modern paints; Lightfastness index; UV ageing

Novel approach to the microscopic inspection during laser cleaning treatments of artworks by I. Cacciari; D. Ciofini; M. Mascalchi; A. Mencaglia; S. Siano (pp. 1585-1591).

The present work focuses on the potential of 3D digital microscopy for assessing micro-morphological features during laser cleaning treatments of artworks. This application requires preliminary optimization studies aimed at defining operative irradiation parameters and practicable degree of cleaning, as well as in situ diagnostic assessments during the restoration work. To this goal, we developed and tested a dedicated 3D digital microscope by implementing the “shape-from-focus” technique. The significant potential of this instrument, which provides textural and chromatic information, was proven for the phenomenological characterization of black crust removal from stones, earthy concretion from bronzes and dark varnish from easel paintings. Comparative measurements using 3D digital microscopy and contact microprofilometry were performed after laser cleaning tests of prepared samples, genuine archaeological bronze artefacts and a stone sculptural element from Florence’s Dome. The results achieved demonstrate the effectiveness and reliability of the novel approach and the advantages it provides with respect to alternative techniques, which will allow the methods to be used in the wider restoration community.

Keywords: Laser cleaning; 3D microscopy; Surface roughness

Evaluation of a novel ELISA for serotonin: urinary serotonin as a potential biomarker for depression by Mikaela I. Nichkova; Han Huisman; Paul M. Wynveen; David T. Marc; Kelly L. Olson; Gottfried H. Kellermann (pp. 1593-1600).

Depression is a common disorder with physical and psychological manifestations often associated with low serotonin. Since noninvasive diagnostic tools for depression are sparse, we evaluated the clinical utility of a novel ELISA for the measurement of serotonin in urine from depressed subjects and from subjects under antidepressant therapy. We developed a competitive ELISA for direct measurement of serotonin in derivatized urine samples. Assay performance was evaluated and applied to clinical samples. The analytical range of the assay was from 6.7 to 425 μg serotonin/g creatinine (Cr). The limit of quantification was 4.7 μg/g Cr. The average recovery for spiked urine samples was 104.4%. Average intra-assay variation was 4.4%, and inter-assay variation was <20%. The serotonin analysis was very specific. No significant interferences were observed for 44 structurally and nonstructurally related urinary substances. Very good correlation was observed between urinary serotonin levels measured by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS; ELISA = 1.16 × LC-MS/MS − 53.8; r = 0.965; mean % bias = 11%; n = 18). Serotonin was stable in acidified urine for 30 days at room temperature and at −20 °C. The established reference range for serotonin was 54–366 μg/g Cr (n = 64). Serotonin levels detected in depressed patients (87.53 ± 4.89 μg/g Cr; n = 60) were significantly lower (p < 0.001) than in nondepressed subjects (153.38 ± 7.99 μg/g Cr). Urinary excretion of serotonin in depressed individuals significantly increased after antidepressant treatment by 5-hydroxy-tryptophane and/or selective serotonin re-uptake inhibitor (p < 0.01). The present ELISA provides a convenient and robust method for monitoring urinary serotonin. It is suitable to monitor serotonin imbalances and may be particularly helpful in evaluating antidepressant therapies. Figure Monitoring urinary serotonin by ELISA in depressed patients under antidepressant therapy by 5-HTP, SSRIs and a combination of both

Keywords: Immunoassay; ELISA; Urine; 5-Hydroxytryptamine; Depression; Antidepressants

Convenient formation of nanoparticle aggregates on microfluidic chips for highly sensitive SERS detection of biomolecules by Jianhua Zhou; Kangning Ren; Yihua Zhao; Wen Dai; Hongkai Wu (pp. 1601-1609).

Microfluidic chips combined with surface-enhanced Raman spectroscopy (SERS) offer an outstanding platform for rapid and high-sensitivity chemical analysis. However, it is nontrivial to conveniently form nanoparticle aggregrates (as SERS-active spots for SERS detection) in microchannels in a well-controlled manner. Here, we present a rapid, highly sensitive and label-free analytical technique for determining bovine serum albumin (BSA) on a poly(dimethylsiloxane) (PDMS) microfluidic chip using SERS. A modified PDMS pneumatic valve and nanopost arrays at the bottom of the fluidic microchannel are used for reversibly trapping gold nanoparticles to form gold aggregates, creating SERS-active spots for Raman detection. We fabricated a chip that consisted of a T-shaped fluidic channel and two modified pneumatic valves, which was suitable for fast loading of samples. Quantitative analysis of BSA is demonstrated with the measured peak intensity at 1,615 cm⁻¹ in the surface-enhanced Raman spectra. With our microfluidic chip, the detection limit of Raman can reach as low as the picomolar level, comparable to that of normal mass spectrometry. Figure A convenient strategy for rapid formation of gold nanoparticle aggregates on microfluidic chips was developed. A modified poly(dimethylsiloxane) pneumatic valve and nanopost arrays at the bottom of the fluidic microchannel were used for reversibly trapping gold nanoparticles to form gold aggregates, creating SERS-active spots for sensitive surface-enhanced Raman spectroscopy detection. The detection limit of Raman can reach as low as the picomolar level with our microfluidic chip.

Keywords: Microfluidics; Gold nanoparticles; Aggregates; Surface-enhanced Raman spectroscopy; Highly sensitive detection

Quantitative trace analysis of a broad range of antiviral drugs in poultry muscle using column-switch liquid chromatography coupled to tandem mass spectrometry by Bjorn J. A. Berendsen; Robin S. Wegh; Martien L. Essers; Alida A. M. Stolker; Stefan Weigel (pp. 1611-1623).

A liquid chromatography–tandem mass spectrometry method for the analysis of seven antiviral drugs, zanamivir, ribavirin, oseltamivir, oseltamivir carboxylate, amantadine, rimantadine and arbidol, in poultry muscle is reported. The antiviral drugs were extracted from the homogenized poultry muscle sample using methanol. The extract was purified using tandem solid-phase extraction combining a cation exchange cartridge and a phenylboronic acid cartridge. To prevent excessive matrix effects, the analytes were separated from the matrix constituents using a column-switch liquid chromatography system combining a reversed-phase and a Hypercarb analytical column. Detection was carried out using tandem mass spectrometry. The method was fully validated according to 2002/657/EC [1] and proved to be adequate for quantification and confirmation of zanamivir and ribavirin at 10 μg kg⁻¹, oseltamivir, oseltamivir carboxylate, amantadine and rimantadine at levels below 1.0 μg kg⁻¹ and for qualitative confirmatory analysis of arbidol at levels below 1 μg kg⁻¹.

Keywords: Antiviral drugs; Mass spectrometry; Poultry muscle; Residue analysis

Species-specific identification of ruminant components contaminating industrial crude porcine heparin using real-time fluorescent qualitative and quantitative PCR by Qing Huang; Ting Xu; Gui-Yu Wang; Jun-Fu Huang; Han Xia; Richard Yin; Angie Tang; Wei-Ling Fu (pp. 1625-1634).

Ever since the emergence of bovine spongiform encephalopathy, the source of pharmaceutical heparin has been restricted to porcine intestinal mucosa. In this project, two real-time fluorescent PCR methods were developed to assist with quality control analysis. The first is a qualitative method which relies on SYBR Green I chemistry to confirm the porcine origin of industrial crude porcine heparin (ICPH), identify any ruminant contaminants, and generally control purity. The second is based on TaqMan chemistry and is able to quantitatively identify porcine, bovine, caprine, and ovine components and contaminants in ICPH. By targeting mitochondrial DNA, both PCR systems showed a detection limit of 1 pg DNA and amplification efficiencies ranging between 96% and 102%. Moreover, quantitative PCR showed a detection limit of 0.02 ppm in samples comprising porcine, bovine, caprine, and ovine DNA. The results of qualitative PCR over 27 ICPH samples showed that all samples were porcine in origin and that 17 had ruminant contaminants. The results of quantitative PCR further showed that out of all 17 samples with ruminant contaminants, seven samples had bovine, ovine, and caprine contaminants, two samples had bovine and ovine contaminants, and eight samples had only ovine contaminants. In conclusion, the qualitative PCR system was found to be a relatively inexpensive, rapid, and flexible method of identifying the porcine origin of and ruminant contaminants in ICPH, while the quantitative PCR was found suitable to accurately analyze the components and contaminants in detail. Both methods are suitable for routine control assays for the evaluation of ICPH purity and origins of contaminants.

Keywords: Industrial crude porcine heparin; Ruminant; Detection; Species-specific identification; Real-time fluorescent PCR

Quantification of plasma homocitrulline using hydrophilic interaction liquid chromatography (HILIC) coupled to tandem mass spectrometry by Stéphane Jaisson; Laëtitia Gorisse; Christine Pietrement; Philippe Gillery (pp. 1635-1641).

Homocitrulline (HCit), an amino acid formed by the carbamylation of ε-amino groups of lysine residues, is considered a promising biomarker for monitoring diseases such as chronic renal failure and atherosclerosis. This paper describes a tandem mass spectrometric method for total, protein-bound and free HCit measurement in plasma samples. HCit was separated from other plasma components by hydrophilic interaction liquid chromatography. Detection was achieved by monitoring transitions of 190.1 > 127.1 and 190.1 > 173.1 for HCit, and 183.1 > 120.2 for d₇-citrulline used as internal standard. This method allowed HCit quantification within 5.2 min and was precise (inter-assay CV < 5.85%), accurate (mean recoveries ranging from 97% to 106%), and exhibited a good linearity from 10 nmol/L to 1.6 μmol/L. Plasma samples from control and uremic mice (n = 10) were analyzed. In control mice, mean total plasma HCit concentration was 0.78 ± 0.12 μmol/mol amino acids, whereas it was increased 2.7-fold in uremic mice plasma, reaching 2.10 ± 0.50 μmol/mol amino acids (p < 0.001). In conclusion, this method exhibits good analytical performances and meets the criteria of sensitivity suitable for HCit concentration assessment in plasma samples.

Keywords: Homocitrulline; Carbamylation; Plasma; LC-MS/MS

A high-resolution phosphorus-31 nuclear magnetic resonance (NMR) spectroscopic method for the non-phosphorus markers of chemical warfare agents by Avik Mazumder; Ajeet Kumar; Ajay K. Purohit; Devendra K. Dubey (pp. 1643-1652).

A high-resolution phosphorus-31 nuclear magnetic resonance (NMR) spectroscopic method has been developed for detection, identification and quantification of non-phosphorus markers of toxic nerve agents (soman and V-class), vesicants (HD, HN-2, HN-3), and incapacitating agent (Bz). These analytes were converted to phosphorus-containing derivatives via phosphitylation reaction of their hydroxyl and sulfhydryl functions (using 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane). This was followed by ³¹P{¹H} and ³¹P NMR analysis of these derivatives. The chemical shifts (δ) and coupling constants (³ J _P–H) of derivatives were used for their specific detection and identification. The method allowed clear distinction between the alcohols and thiols. The lower limits of detection of these analytes were found to be between 12 and 28 μg obtained from 128 transients of ³¹P{¹H} quantitative NMR experiments. Utility of the method was ensured by the detection and identification of triethanolamine present (at an original concentration of 5 μg/mL) in an aqueous sample from 28th OPCW Official Proficiency Tests. Figure A conclusive method for identification of non-phosphorus markers of Chemical Warfare Agents

Keywords: Nuclear magnetic resonance; Nerve agents; Vesicants; Chemical warfare agents; Phosphitylation

Solution-state NMR spectroscopy of famotidine revisited: spectral assignment, protonation sites, and their structural consequences by Attila Marosi; Zsófia Szalay; Szabolcs Béni; Zoltán Szakács; Tamás Gáti; Ákos Rácz; Béla Noszál; Ádám Demeter (pp. 1653-1666).

Multinuclear one (1D-) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopic investigations of famotidine, the most potent and widely used histamine H₂-receptor antagonist, were carried out in dimethyl sulfoxide-d₆ (DMSO-d₆) and water. Previous NMR assignments were either incomplete or full assignment was based only on 1D spectra and quantum-chemical calculations. Our work revealed several literature misassignments of the ¹H, ¹³C, and ¹⁵N NMR signals and clarified the acid–base properties of the compound at the site-specific level. The erroneous assignment of Baranska et al. (J. Mol. Struct. 2001, 563) probably originates from an incorrect hypothesis about the major conformation of famotidine in DMSO-d₆. A folded conformation similar to that observed in the solid-state was also assumed in solution, stabilized by an intramolecular hydrogen bond involving one of the sulphonamide NH₂ protons and the thiazole nitrogen. Our detailed 1D and 2D NMR experiments enabled complete ab initio ¹H, ¹³C, and ¹⁵N assignments and disproved the existence of the sulphonamide NH hydrogen bond in the major conformer. Rather, the molecule is predominantly present in an extended conformation in DMSO-d₆. The aqueous acid–base properties of famotidine were studied by 1D ¹H- and 2D ¹H/¹³C heteronuclear multiple-bond correlation (HMBC) NMR-pH titrations. The experiments identified its basic centers including a new protonation step at highly acidic conditions, which was also confirmed by titrations and quantum-chemical calculations on a model compound, 2-[4-(sulfanylmethyl)-1,3-thiazol-2-yl]guanidine. Famotidine is now proved to have four protonation steps in the following basicity order: the sulfonamidate anion protonates at pH = 11.3, followed by the protonation of the guanidine group at pH = 6.8, whereas, in strong acidic solutions, two overlapping protonation processes occur involving the amidine and thiazole moieties. Figure Correct amidine assignments and protonation sites of famotidine

Keywords: Famotidine; Famotidone; NMR assignment; NMR titration; pK _a ; Conformation

Critical assessment of the elemental composition of Corning archeological reference glasses by LA-ICP-MS by B. Wagner; A. Nowak; E. Bulska; K. Hametner; D. Günther (pp. 1667-1677).

Corning archeological reference glasses A, B, C, and D have been made to simulate different historic technologies of glass production and are used as standards in historic glass investigations. In this work, nanoseconds (193, 266 nm) and femtosecond (800 nm) laser ablation were used to study the elemental composition of Corning glasses using laser ablation inductively coupled plasma mass spectrometry. The determined concentrations of 26 oxides (Li₂O, B₂O₃, Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, V₂O₅, Cr₂O₃, MnO, Fe₂O₃, CoO, NiO, CuO, ZnO, Rb₂O, SrO, ZrO₂, SnO₂, Sb₂O₅, BaO, PbO, Bi₂O₃) are compared with values reported in the literature. Results show variable discrepancies between the data, with the largest differences found for Cr₂O₃ in Corning A; Li₂O, B₂O₃, and Cr₂O₃ in Corning B; and MnO, Sb₂O₅, Cr₂O₃, and Bi₂O₃ in Corning C. The best agreement between the measured and literature values was found for Corning D. However, even for this reference, glass re-evaluation of the data was necessary and new values for PbO, BaO, and Bi₂O₃ are proposed. Figure The results of Corning glasses obtained by LA-ICP-MS after ablation by different laser wavelenghts presented as the ratios of the measured to the recommended values

Keywords: Glass; Standards; Archeometry; LA-ICP-MS

Optimization of a dispersive liquid–liquid microextraction method for the analysis of benzotriazoles and benzothiazoles in water samples by Ma. Teresa Pena; X. Vecino-Bello; Ma. Carmen Casais; Ma. Carmen Mejuto; Rafael Cela (pp. 1679-1695).

A simple and rapid dispersive liquid–liquid microextraction method has been developed for the determination of 11 benzotriazoles and benzothiazoles in water samples. Tri-n-butylphosphate (TBP) was used as extractant, thus avoiding the use of toxic water-immiscible chlorinated solvents. The influence of several variables (e.g., type and volume of dispersant and extraction solvents, sample pH, ionic strength, etc.) on the performance of the sample preparation step was systematically evaluated. Analytical determinations were carried out by high-performance liquid chromatography with fluorescence and UV detection and liquid chromatography–electrospray ionization-tandem mass spectrometry. The optimized method exhibited a good precision level with relative standard deviation values between 3.7% and 8.4%. Extraction yields ranging from 67% to 97% were obtained for all of these considered compounds. Finally, the proposed method was successfully applied to the analysis of benzotriazoles and benzothiazoles in real water samples (tap, river, industrial waters, and treated and raw wastewaters).

Keywords: Benzotriazoles; Benzothiazoles; Dispersive liquid–liquid microextraction; Water analysis; Liquid chromatography

Selective accurate-mass-based analysis of 11 oxy-PAHs on atmospheric particulate matter by pressurized liquid extraction followed by high-performance liquid chromatography and magnetic sector mass spectrometry by C. Walgraeve; K. Demeestere; P. De Wispelaere; J. Dewulf; J. Lintelmann; K. Fischer; H. Van Langenhove (pp. 1697-1711).

An innovative analytical method based on high-performance liquid chromatography and atmospheric pressure chemical ionization magnetic sector mass spectrometry was developed and optimized to determine trace concentrations of 11 compounds belonging to the group of the seldom-analyzed oxy-PAHs (phenanthrene-9,10-dione, chrysene-5,6-dione, benzo[a]pyrene-4,5-dione, benzo[a]pyrene-1,6-dione, benzo[a]pyrene-3,6-dione, benzo[a]pyrene-6,12-dione, 4-oxa-benzo[def]chrysene-5-one, pyrene-1-carboxaldehyde, benzo[de]anthracene-7-one, benzo[a]anthracene-7,12-dione, and napthacene-5,12-dione) on airborne particulate matter (PM₁₀). The mass spectrometer was operated in multiple ion detection mode, allowing for selective accurate mass detection (mass resolution of 12,000 full width at half maximum) of the oxy-PAHs characteristic ions. Optimization of both the vaporizer (450 °C) and capillary temperature (350 °C) resulted into instrumental detection limits in the range between 7 (benzo[a]pyrene-1,6-dione) and 926 pg (benzo[a]anthracene-7,12-dione). The advanced pressurized liquid extraction (PLE) and the more traditionally used ultrasonic extraction (USE) were compared using ethyl acetate as an extraction solvent. For both techniques, high recoveries from spiked quartz fiber filters (PLE, 82–110%; USE, 67–97%) were obtained. Recoveries obtained from real PM₁₀ samples were also high (76–107%), and no significant matrix effects (ME) on the ionization process (enhancement or suppression) were found (ME, 89–123%). Method limits of quantification (S/N = 10) were in the range between 2 and 336 pg/m³. This method was used to analyze real PM samples collected at several urban and rural locations in the Antwerp area. For the first time, concentrations for Belgium are provided. Concentrations of individual oxy-PAHs are in the lower pictograms per cubic meter to 6 ng/m³ range. High concentration differences between individual compounds are found as exemplified by the 75th percentile of the phenanthrene-9,10-dione and benzo[de]anthracene-7-one concentrations being a factor of 4 to 22 higher compared with the other target oxy-PAHs. Figure Analysis of 11 oxy-PAHs on airborne particulate matter (PM₁₀).

Keywords: Pressurized liquid extraction; Ultrasonic extraction; Oxy-PAHs; Magnetic sector mass spectrometry; HPLC; Flanders

Preparation and certification of Hijiki reference material, NMIJ CRM 7405-a, from the edible marine algae hijiki (Hizikia fusiforme) by Tomohiro Narukawa; Kazumi Inagaki; Yanbei Zhu; Takayoshi Kuroiwa; Izumi Narushima; Koichi Chiba; Akiharu Hioki (pp. 1713-1722).

A certified reference material, NMIJ CRM 7405-a, for the determination of trace elements and As(V) in algae was developed from the edible marine hijiki (Hizikia fusiforme) and certified by the National Metrology Institute of Japan (NMIJ), the National Institute of Advanced Industrial Science and Technology (AIST). Hijiki was collected from the Pacific coast in the Kanto area of Japan, and was washed, dried, powdered, and homogenized. The hijiki powder was placed in 400 bottles (ca. 20 g each). The concentrations of 18 trace elements and As(V) were determined by two to four independent analytical techniques, including (ID)ICP-(HR)MS, ICP-OES, GFAAS, and HPLC-ICP-MS using calibration solutions prepared from the elemental standard solution of Japan calibration service system (JCSS) and the NMIJ CRM As(V) solution, and whose concentrations are certified and SI traceable. The uncertainties of all the measurements and preparation procedures were evaluated. The values of 18 trace elements and As(V) in the CRM were certified with uncertainty (k = 2).

Keywords: Certification; Certified reference material; Trace elements; Hijiki; Arsenic species; Speciation

Determination of synthetic polycyclic musks in aqueous samples by ultrasound-assisted dispersive liquid–liquid microextraction and gas chromatography–mass spectrometry by Ching-Ya Yang; Wang-Hsien Ding (pp. 1723-1730).

A simple and solvent-minimized procedure for the determination of six commonly found synthetic polycyclic musks in aqueous samples using ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) coupled with gas chromatography–mass spectrometry (GC-MS) is described. The parameters affecting the extraction efficiency of analytes from water samples were systematically investigated. The best extraction conditions involved the rapid injection of a mixture of 1.0 mL of isopropyl alcohol (as a dispersant) and 10 μL of carbon tetrachloride (as an extractant) into 10 mL of water containing 0.5 g of sodium chloride in a conical-bottom glass tube. After ultrasonication for 1.0 min and centrifugation at 5,000 rpm (10 min), the sedimented phase 1.0 μL was directly injected into the GC-MS system. The limits of quantitation (LOQs) were less than 0.6 ng/L. The precision for these analytes, as indicated by relative standard deviations (RSDs), was less than 11% for both intra- and interday analysis. Accuracy, expressed as the mean extraction recovery, was between 71 and 104%. Their total concentrations were determined in the range from 8.3 to 63.9 ng/L in various environmental samples by using a standard addition method.

Keywords: Synthetic polycyclic musks; Ultrasound-assisted dispersive liquid–liquid microextraction; GC-MS; Water analysis

Computational analysis of non-covalent polymer–protein interactions governing antibody orientation by Leslie R. Farris; Melisenda J. McDonald (pp. 1731-1736).

The ALYGNSA is an affinity-based antibody orientation system produced through the interaction of the polymer poly(methyl methacrylate) (PMMA) and recombinant protein G (rProG), a streptococcal protein. This improved orientation suggests a specific non-covalent attachment of the rProG to PMMA that leaves the IgG binding region of the rProG more readily available. In this study, a full tertiary structure model of the rProG molecule of 198 amino acid residues containing a signal region, two IgG binding domains, and an anchor region, was computationally generated using the iterative threading assembly refinement (I-Tasser) server. The rProG model having the highest confidence score was subject to docking experiments with varied-length short chains of PMMA polymer via the graphic processing units-based Hex server. A five-residue section of the rProG anchor region, with the sequence TPATP, was identified as a potential interaction site. A complete ternary model (rProG, PMMA, and IgG) was assembled and provides insight into a plausible mechanism for non-covalent antibody orientation by the ALYGNSA system.

Keywords: Protein–polymer interactions; Antibody orientation; ALYGNSA; I-TASSER protein modeling server; Hex protein docking server; Biosensors

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Analytical and Bioanalytical Chemistry (v.402, #4)