Quantitative Compositional Data Research Articles

On, under and beneath the patina: Evaluation of micro energy dispersive X-ray fluorescence quantitative data on the classification of archaeological copper alloys

A series of quantitative micro X-ray fluorescence (μ-XRF) analyses was performed on a) corroded surface, b) stripped-patina area and c) polished cross section of twenty-five archaeological copper alloys from Iran in order to check the viability of quantitative XRF data for the classification of ancient copper alloys. The limits of detection and quantification and, also, the precision and accuracy of the analytical data were measured using twelve certified reference materials (CRM). The compositional data obtained through these three approaches were statistically evaluated comparing with the compositional data on the same samples obtained by the inductively coupled plasma – optical emission spectroscopy (ICP-OES). We demonstrated that the corroded surfaces are depleted in Ni and Zn and enriched in Pb, Sn and As. Also, we suggest that although μ-XRF quantitative compositional data collected from the corroded surfaces may result in misleading information, the areas with the lowest Sn concentration may represent the closest compositional data to the absolute quantity of Cu, Zn, As and Pb in ancient copper alloys. Moreover, it is shown that the quantitative μ-XRF data obtained from the stripped-patina surface and those from the polished cross sections are comparable with the ICP-OES compositional data and can be confidently used for determining the diversity and technology of ancient copper alloys.

Chemical and physical heterogeneity within native gold: implications for the design of gold particle studies

Studies of populations of gold particles are becoming increasingly common; however, interpretation of compositional data may not be straightforward. Natural gold is rarely homogenous. Alloy heterogeneity is present as microfabrics formed either during primary mineralization or by modification of pre-existing alloys by chemical and physical drivers during subsequent residence in either hypogene or surficial environments. In electron-probe-microanalysis (EPMA)-based studies, the combination of Cu, Hg, and Pd values and mineral inclusion suites may be diagnostic for source style of mineralization, but Ag alone is rarely sufficient. Gold characterization studies by laser-ablation-ICP mass spectrometry linked to both quadrupole and Time-of-Flight (ToF-MS) systems show that only Ag, Cu, and Hg form homogenous alloys with Au sufficiently often to act as generic discriminants. Where present, other elements are commonly distributed highly heterogeneously at the micron or submicron scale, either as mineral inclusions or in highly localized, but low concentrations. Drawing upon our own data derived from individual inspection and analyses of approximately 40,000 gold particles from 526 placer and in situ localities worldwide, we show that adequate characterization of gold from a specific locality normally requires study of a minimum of 150 particles via a two-stage approach comprising spatial characterization of compositional heterogeneity, plus crystallographic orientation mapping, that informs subsequent targeted acquisition of quantitative compositional data by EPMA and/or laser-ablation ICP-MS methods. Such data provide the platform to review current understanding of the genesis of gold particle characteristics, elevating future compositional studies from empirical descriptions to process-focused interpretations.

The influence of temperature and pressure on macro- and micro-mixing in compressed fluid flows; mixing of carbon dioxide and ethanol above their mixture critical pressure

We report quantitative composition data on continuous jet-mixing of ethanol with ambient carbon-dioxide (CO2) at temperatures (T=[313 K–333 K]) and pressures (p=[9 MPa to 11 MPa]) in the vicinity of the mixture critical pressure of the binary system. Progress of mixing is quantified simultaneously on the macro- and on the micro-scale. The lag between mixing on both scales is quantified spatially resolved and in the jet-mixing region. We found that surprisingly mixing below the mixture critical pressure in the two-phase mixing regime can be more efficient than mixing above the mixture critical pressure in the single-phase mixing regime. Density was the key parameter influencing the mixing efficiency.

Use of gas cluster ion source depth profiling to study the oxidation of fullerene thin films by XPS

The analysis of organic materials such as phenyl-C61-butyric acid methyl ester (PC61BM) by depth profiling is typically fraught with difficulty due to the fragile nature of the sample. In this work we utilise a gas cluster ion source for the controlled depth profiling of organic materials that would historically have been too fragile to analyse and obtain quantitative compositional data through the whole thickness of the film. In particular we examine the oxygen diffusion and photo-oxidation kinetics of one of the most commonly used electron acceptor materials for many organic optoelectronic applications, namely PC61BM, in both neat films and in blends with polystyrene. Exposure to AM1.5G light and air under ambient conditions, results in a higher level of surface oxidation of blended PC61BM:polystyrene than is observed for either pure control film. Gas cluster ion source depth profiling further confirms that this oxidation is strongest at the extreme surface, but that over time elevated oxygen levels associated with oxidised organic species are observed to penetrate through the whole blended film. The results presented herein provide further insights on the environmental stability of fullerene based organic optoelectronic devices.

Quantitative allochem compositional analysis of Lochkovian-Pragian boundary sections in the Prague Basin (Czech Republic)

Quantitative allochem compositional trends across the Lochkovian-Pragian boundary Event were examined at three sections recording the proximal to more distal carbonate ramp environment of the Prague Basin. Multivariate statistical methods (principal component analysis, correspondence analysis, cluster analysis) of point-counted thin section data were used to reconstruct facies stacking patterns and sea-level history. Both the closed-nature allochem percentages and their centred log-ratio (clr) coordinates were used. Both these approaches allow for distinguishing of lowstand, transgressive and highstand system tracts within the Praha Formation, which show gradual transition from crinoid-dominated facies deposited above the storm wave base to dacryoconarid-dominated facies of deep-water environment below the storm wave base. Quantitative compositional data also indicate progradative-retrogradative trends in the macrolithologically monotonous shallow-water succession and enable its stratigraphic correlation with successions from deeper-water environments. Generally, the stratigraphic trends of the clr data are more sensitive to subtle changes in allochem composition in comparison to the results based on raw data. A heterozoan-dominated allochem association in shallow-water environments of the Praha Formation supports the carbonate ramp environment assumed by previous authors.

Discerning differences: Ion beam analysis of ancient faience from Naukratis and Rhodes

Faience technology was known in Egypt since the Predynastic Period and practiced for a period also in Bronze Age Greece, but, having been lost, was reintroduced to the Greek world only in the first half of the first millennium BC. The Greek island of Rhodes and the Greek-Egyptian trade harbour of Naukratis in the Nile Delta are suspected to be key centres of early Greek-style faience production, exporting amulets and vessels across the Mediterranean region. Yet the nature and scale of their production and their role in technology transfer, vis-à-vis Egyptian and Levantine/Phoenician production, remain little understood. The main aim of this study was to discover whether it is possible to define chemical characteristics for the faience produced and found at Naukratis, and to use this data to differentiate between artefacts produced here and elsewhere.A programme of ion beam (PIXE and PIGE) analysis was conducted under the CHARISMA transnational access scheme, known to be a suitable tool for studying ancient vitreous artefacts as it provides a non-destructive means of obtaining precise and accurate quantitative compositional data. Both the internal body of damaged objects as well as the outer glaze layer were analysed, of which only the latter are discussed here. The results of this study indicate that the faience found at both Naukratis and on Rhodes is compositionally similar. However, some small differences were found in the raw materials used in its production which may help us to better characterise the production of different faience manufacturing centres.

Structures and Analysis of Carotenoid Molecules.

Modifications of the usual C40 linear and symmetrical carotenoid skeleton give rise to a wide array of structures of carotenes and xanthophylls in plant tissues. These include acyclic, monocyclic and dicyclic carotenoids, along with hydroxy and epoxy xanthophylls and apocarotenoids. Carotenols can be unesterified or esterified (monoester) in one or two (diester) hydroxyl groups with fatty acids. E-Z isomerization increases the array of possible plant carotenoids even further. Screening and especially quantitative analysis are being carried out worldwide. Visible absorption spectrometry and near infrared reflectance spectroscopy have been used for the initial estimation of the total carotenoid content or the principal carotenoid content when large numbers of samples needed to be analyzed within a short time, as would be the case in breeding programs. Although inherently difficult, quantitative analysis of the individual carotenoids is essential. Knowledge of the sources of errors and means to avoid them has led to a large body of reliable quantitative compositional data on carotenoids. Reverse-phase HPLC with a photodiode array detector has been the preferred analytical technique, but UHPLC is increasingly employed. HPLC-MS has been used mainly for identification and NMR has been useful in unequivocally identifying geometric isomers.

Infrared Fiber Optic Probe Evaluation of Degenerative Cartilage Correlates to Histological Grading

Background: Osteoarthritis (OA), a degenerative cartilage disease, results in alterations of the chemical and structural properties of tissue. Arthroscopic evaluation of full-depth tissue composition is limited and would require tissue harvesting, which is inappropriate in daily routine. Fourier transform infrared (FT-IR) spectroscopy is a modality based on molecular vibrations of matrix components that can be used in conjunction with fiber optics to acquire quantitative compositional data from the cartilage matrix. Purpose: To develop a model based on infrared spectra of articular cartilage to predict the histological Mankin score as an indicator of tissue quality. Study Design: Comparative laboratory study. Methods: Infrared fiber optic probe (IFOP) spectra were collected from nearly normal and more degraded regions of tibial plateau articular cartilage harvested during knee arthroplasty (N = 61). Each region was graded using a modified Mankin score. A multivariate partial least squares algorithm using second-derivative spectra was developed to predict the histological modified Mankin score. Results: The partial least squares model derived from IFOP spectra predicted the modified Mankin score with a prediction error of approximately 1.4, which resulted in approximately 72% of the Mankin-scored tissues being predicted correctly and 96% being predicted within 1 grade of their true score. Conclusion: These data demonstrate that IFOP spectral parameters correlate with histological tissue grade and can be used to provide information on tissue composition. Clinical Relevance: Infrared fiber optic probe studies have significant potential for the evaluation of cartilage tissue quality without the need for tissue harvest. Combined with arthroscopy, IFOP analysis could facilitate the definition of tissue margins in debridement procedures.

Clustering and Local Magnification Effects in Atom Probe Tomography: A Statistical Approach

Local magnification effects and trajectory overlaps related to the presence of a second phase (clusters) are key problems and still open issues in the assessment of quantitative composition data in three-dimensional atom probe tomography (APT) particularly for tiny solute-enriched clusters. A model based on the distribution of distance of first nearest neighbor atoms has been developed to exhibit the variations in the apparent atomic density in reconstructed volumes and to correct compositions that are biased by local magnification effects. This model was applied to both simulated APT reconstructions and real experimental data and shows an excellent agreement with the expected composition of clusters.

Abandoned mine slags analysis by EPMA WDS X-ray mapping

Mining activity on the Iberian Pyritic Belt (Portugal and Spain) started before Phoenician times, became particularly intense during the Roman occupation of the Iberian Peninsula (for gold), and after the industrial revolution (for gold, copper, zinc, lead and sulphur).The commonest ore of this region is a massive polymetalic sulphide accumulation, where pyrite (FeS2) is the main mineral, with variable concentrations of chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), arsenopyrite (FeAsS2), other sulphides and sulfosalts which include minor elements like Mn, Co, Ni, Se, Cd, Sb, Te, Hg and Bi. Some of the main and minor elements of these ores are hazardous and the drainage basins of pollutant source areas often induce health concerns in the resident population. Electron probe microanalysis study followed previous optical and XRD analysis of the slags. The study focused on the identification of phases how sulphide and metallic phases are distributed within the material and infer about leachable elements during weathering. Electron probe X-ray maps show evidences of different behaviour between the elements: Ca and Zn are completely leached; iron is retained in oxyhydroxides, lead and arsenic precipitate as sulphates.Electron probe microanalysis studies are essential to understand complex materials as earth materials. Nevertheless, care is required to a correct interpretation of data and most quantitative compositional data are not trustworthy.

Towards biomolecular aided agriculture: metabolic fingerprint of wild and cultivated Sicilian medicinal plants belonging to the folk tradition

For chemotaxonomic and agro-technological purposes, extracts of wild thyme (Thymus vulgaris L., 30 samples), oregano (Origanum vulgare L., 61 samples) and rosemary (Rosmarinus officinalis L., 57 samples) collected in different areas of the Sicilian region, as well as cultivated sage (Salvia officinalis L., 7 samples), were screened for their phenolic compound content. All these plants belong to Sicilian culinary tradition and folk remedies. In order to have as many details as possible on the composition of these plants and their variation, extracts of different polarity (lipidic and alcoholic) for each cultivar were obtained and analysed. Several groups of selected molecules, typical of the different species and a part of their secondary metabolism (chemotaxonomical markers), were chosen, containing flavonoids, terpenoids, and organic acids as more representative chemical classes. The markers were firstly identified in the extracts through exhaustive analyses using the LC/UV-DAD/MS technique and then processed with high-throughput HPLC to obtain qualitative and quantitative compositional data. These data, together with the yield of extractions from the vegetable material, provided enough information to build up an analytical matrix from which the best extract in terms of presence and percentage of polyphenols could be selected.

Use of QEMSCAN ® for the characterization of Ni-rich and Ni-poor goethite in laterite ores

Nickel laterites are mineralogically complex, yet increasingly important sources of nickel and cobalt. To be successfully exploited they require accurate characterization of the mineralogy, texture and grade. As spatially resolved mineralogical techniques, automated scanning electron microscopy-based analysis systems (such as QEMSCAN ®) offer significant advantages over traditional bulk compositional and mineralogical methods. This project tests how QEMSCAN ® can be employed to characterize goethite and potentially interfering mineral compounds in nickel laterites. This involves the development and testing of a Species Identification Protocol (SIP) that discriminates goethite on the basis of nickel, chromium, and manganese content. The SIP is calibrated to quantitative compositional data obtained by electron-probe microanalysis (EPMA). The SIP is tested on ore specimens from Çaldağ (Turkey), Acoje (the Philippines) and Devolli (Albania). The project demonstrates the advantages of increased X-ray acquisition rate for the characterization of low-Ni concentrations and the significance of EPMA analysis for the quantitative validation of mineral identifications in the SIP.

Determination of the composition of Ultra‐thin Ni‐Si films on Si: constrained modeling of electron probe microanalysis and x‐ray reflectivity data

AbstractThe homogeneous bulk assumption used in traditional electron probe microanalysis (EPMA) can be applied for thin‐layered systems with individual layers as thick as 50 nm provided the penetration depth of the lowest accelerating voltage exceeds the total film thickness. Analysis of an NIST Ni‐Cr thin film standard on Si using the homogeneous model yielded certified compositions and application of the same model to ultra‐thin Ni‐Si layers on GaAs yielded their expected compositions. In cases where the same element is present in multiple layers or in the substrate as well as the film, the homogeneous assumption in EPMA alone is not sufficient to determine composition. By combining x‐ray reflectivity (XRR) thickness and critical angle data and using an iterative approach, quantitative compositional data in EPMA can be achieved. This technique was utilized to determine the composition of Ni‐Si ultra‐thin films grown on silicon. The Ni‐Si composition determined using this multi‐instrumental technique matched that of Ni‐Si films simultaneously deposited on GaAs. Copyright © 2008 John Wiley & Sons, Ltd.

Carbonic fluids in ultrahigh-temperature metamorphism: evidence from Raman spectroscopic study of fluid inclusions in granulites from the Napier Complex, East Antarctica

Abstract We report the first quantitative compositional data on fluid inclusions in ultrahigh-temperature (UHT) granulites from the Napier Complex of Enderby Land, East Antarctica. Fluid inclusions in various high-grade minerals such as garnet, orthopyroxene and sapphirine from three UHT localities in the Amundsen Bay area were studied in terms of petrography and microthermometry as well as laser Raman spectroscopy. Measured melting temperatures of inclusions from all the three localities indicate that the trapped fluid phase is dominantly carbonic. Raman analyses confirmed a near pure CO 2 composition with only minor dilutants such as N 2 (<6.0 mol%), CH 4 (<0.3 mol%), and H 2 O (<0.1 mol%). CH 4 -bearing fluid associated with sapphirine granulites suggests low oxygen fugacity ( f O 2 ) conditions for the rocks, whereas CH 4 was not detected from fluid inclusions in magnetite-bearing high- f O 2 garnet granulite. The range of CO 2 isochores computed from density measurements in fluid inclusions from the granulites pass through the peak P – T conditions of the Napier metamorphism ( T = 1050–1150 °C, P =9–11 kbar) indicating synmetamorphic nature of the fluids. Inclusions in garnet from Bunt Island coexist with carbonate minerals (magnesite) and graphite along with dense CO 2 -rich fluid, indicating probable derivation from deep-seated primary magmatic sources. The ubiquitous association of carbonic fluids in the UHT mineral assemblages suggests CO 2 influx during extreme crustal metamorphism of the Napier Complex. The carbonic fluid probably played an important role in transporting heat from mantle or mantle-derived magmas and in stabilizing the dry mineral assemblages.

Fluid characteristics of high- to ultrahigh-temperature metamorphism in southern India: A quantitative Raman spectroscopic study

We report the first quantitative compositional data on fluid inclusions in Late Neoproterozoic to Cambrian ultrahigh-temperature (UHT) granulites from major crustal blocks and shear zones in southern India. Fluid inclusions in various high-grade minerals such as garnet, orthopyroxene, plagioclase, cordierite, and quartz from these rocks were studied in terms of petrography, microthermometry and laser Raman spectroscopy. Measured melting temperatures of the inclusions indicate that the trapped fluid phase is dominantly carbonic. Raman analyses confirmed a CO 2-rich composition with only minor dilutants such as N 2 (≤5.0 mol%), H 2O (≤0.50 mol%), and CH 4 (≤0.47 mol%). The range of most CO 2 isochores computed from density measurements in fluid inclusions from the UHT granulites pass below the peak pressure–temperature conditions of metamorphism indicating considerable resetting of fluid densities during decompression. In contrast, garnetiferous granulites from the Salem area along the Palghat-Cauvery Shear Zone System, which underwent high-pressure prograde metamorphism, contain very high-density syn-metamorphic pure CO 2 inclusions. Such dense carbonic fluid inclusions in garnet and plagioclase coexist with carbonate minerals (calcite or dolomite), indicating probable derivation from deep-seated primary magmatic sources. Although models on the origin of CO 2 are debatable, the ubiquitous association of carbonic fluids in the UHT mineral assemblages is in favour of large-scale infiltration of CO 2-rich fluids during extreme crustal metamorphism associated with collisional orogeny and subsequent extensional collapse at the final stage of amalgamation of the Gondwana supercontinent.

Regiospecific determination of short‐chain triacylglycerols in butterfat by normal‐phase HPLC with on‐line electrospray‐tandem mass spectrometry

This study uses normal-phase HPLC with on-line positive ion electrospray mass spectrometry (ESI-MS) to obtain quantitative compositional data on both synthetic and butterfat short-chain TAG. The product ion tandem MS of standards averaged 11.1 times lower in abundance of the ion formed by cleavage of FA from the sn-2-position for the pairs of regioisomers in the TAG classes: L/L/S-L/S/L and L/S/S-S/L/S, where L denotes long and S short acyl chain (C2-C6). The molar correction factors, determined for 42 regioisomeric pairs of short-chain TAG of 20 randomized mixture of standards, differed by 1.4-80% as the ratios varied between 0.217 and 5.847. Butterfat TAG were resolved into four fractions on short flash chromatography grade silica gel columns. Pairs of regioisomers in the TAG classes L/S/S-S/L/S with predominance of L/S/S isomers and the sole regioisomers in the TAG classes L/L(M)/S were identified by tandem MS, where M denotes either 8:0 or 10:0 acyl chain. The total proportion of L/L(M)/S isomers was estimated at 34.7 and that of L/S/S-S/L/S at 1.0 mol%, including a small proportion of S/S/S. In contrast to previous work, the present data indicate the presence of a small proportion of butyric and caproic acids in the sn-1-position. The overall distribution of the FA in the short-chain TAG of butterfat, calculated from direct MS measurements, was consistent with the results of indirect determinations based on stereospecific analyses of total butterfat.

Quantitative determination of phospholipid compositions by ESI-MS: effects of acyl chain length, unsaturation, and lipid concentration on instrument response

Electrospray ionization-mass spectrometry (ESI-MS) is a very promising tool for the analysis of phospholipid compositions, but is hampered by the fact that not all molecular species are detected with equal efficiency. We studied this and other issues that need to be taken into account to obtain truly quantitative compositional data. The key findings were as follows: First, the instrument response for both saturated and unsaturated phospholipid species decreased with increasing acyl chain length. This effect became increasingly prominent with increasing overall lipid concentration. Second, the degree of acyl chain unsaturation also had a significant effect on instrument response. At the highest concentration studied (10 pmol/microl), polyunsaturated species gave 40% higher intensity than the fully saturated ones. The effect of unsaturation diminished and nearly disappeared with progressive dilution. Third, the instrument response for the different head group classes varied markedly depending on the infusion solvent used. Notably, inclusion of ammonia in the infusion solvent eliminated sodium adduct formation in the positive ion mode, thus greatly simplifying the interpretation of the spectra. The fact that instrument response is dependent on many structural features, overall lipid concentration, solvent composition, and instrument settings makes it necessary to include several internal standards for each phospholipid class to obtain accurate data. Preferably, both unsaturated and saturated standards should be used. Finally, we quantified the major phospholipid classes of BHK cells using ESI-MS. The data agreed closely with those obtained with thin-layer chromatography and phosphorus analysis. This study indicates that quantitative compositional data can be obtained with ESI-MS, provided that proper attention is paid to experimental details, particularly the choice of internal standards.

H.p.l.c. quantitation of hydrocarbon class types in cracked products

H.p.l.c. was optimized to obtain quantitative compositional data on hydrocarbon class type (saturates, olefins, aromatics plus polars) in cracked products from vacuum gas oil (370–500°C) feed over REY zeolite catalyst in a micro-activity test unit. H.p.l.c. separation was achieved using an amino column, a backflush device and nC 6 as mobile phase. An RI detector was used to obtain total saturates and aromatics and a 200 nm u.v. detector to estimate olefins and aromatic hydrocarbons by ring number. Quantitation was achieved using external standard procedure and standards were prepared from the identical petroleum products to obtain response factors. A considerable variation in the liquid product yield during cracking reactions was noticed, from 40 to 70 wt%. Cracking reactions were also favoured through hydrogen transfer, increasing substantially the aromatic content in the range 50–70 wt%. Olefins were also formed during cracking, ranging from 5 to 10 wt%.

Sedimentary record of Late Paleozoic rift and break-up in Northern Gondwana: a case history from the Thini Chu Group and Tamba-Kurkur Formation (Dolpo Tethys Himalaya, Nepal)

Quantitative compositional data from selected sandstone samples in the Upper Paleozoic to lowermost Triassic succession of the central Dolpo Tethys Himalaya (Thini Chu Group and base of the Tamba-Kurkur Formation) are relevant to understand the tectonic and climatic evolution of the northern margin of Gondwana from continental rift to break-up and spreading in the Neotethys Ocean.In central Dolpo, where the Upper Permian is thicker than in other sections of the Northern India and Nepal Tethys Himalaya, and sandstones occur both just below and above the Permian/Triassic boundary, the Thini Chu Group rests discon- formably over Lower Carboniferous carbonates. A terra rossa paleosoil documents a major hiatus that possibly spans the Visean to Early Bashkirian (“rift unconformity”). Another major unconformity overlain by the Murgabian-Midian? “Costiferina arenites” is interpreted as indicating final break-up and initial spreading in Neotethys (“break-up unconformity”). In fact, arenite lenses mantling the unconformity yielded euhe- dral grains of Cr-rich chromian spinel, indicating enhanced partial melting of the asthenosphere rising beneath the Northern India-Nepal “upper plate” margin. Regional correlations indicate a late Early Permian age for this event.LithoZones recognized within the Thini Chu Group are here correlated with formations recently established to the east in Manang (Nepal), largely according to their petrofacies. The Atali Quartzarenite (Petrofacies 1; “white quartzarenites”) best corresponds with the Bangba Fm. of Manang, whereas the “Costiferina arenites” (Petrofacies 2a), the “ochre pelites” and “estuarine quartzarenites” (Petrofacies 2b), and the “black shales and glauco-phosphorites” (Petrofacies 3, 4 and 5) are broadly coeval with Member C of the Puchenpra Formation.Detritai feldspars appear in the middle part of the Thini Chu Group (Petrofacies 2) and sharply and progressively increase upwards (Petrofacies 3), until they peak around the Permian/Triassic boundary (Petrofacies 4 to 5). This trend may be explained with continued uplift of rift shoulders after breakup, or rather with rapidly increasing aridity towards the close of the Permian, while Gondwana was shifting northwards toward the Southern Tropic. Arkosic composition around the Permian/Triassic boundary may be also consistent with an arid episode at global scale.