Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Spectrometry

  • UV-vi spectrometry
  • absorption spectrometry
  • accelerator mass spectrometry
  • atmospheric pressure chemical ionization mass spectrometry
  • atmospheric pressure chemical ionization tandem mass spectrometry
  • atmospheric pressure photoionization mass spectrometry
  • atom bombardment mass spectrometry
  • atomic absorption spectrometry
  • atomic emission spectrometry
  • backscattering spectrometry
  • bombardment mass spectrometry
  • chemical ionization mass spectrometry
  • chemical ionization tandem mass spectrometry
  • chromatography electrospray ionization mass spectrometry
  • chromatography electrospray ionization tandem mass spectrometry
  • chromatography ion trap mass spectrometry
  • chromatography ionisation mass spectrometry
  • chromatography ionization mass spectrometry
  • chromatography ionization tandem mass spectrometry
  • chromatography mass spectrometry
  • chromatography ratio mass spectrometry
  • chromatography tandem mass spectrometry
  • chromatography time-of-flight mass spectrometry
  • chromatography-combustion-isotope ratio mass spectrometry
  • chromatography-mass spectrometry
  • chromatography-tandem mass spectrometry
  • cyclotron resonance mass spectrometry
  • desorption electrospray ionization mass spectrometry
  • desorption ionization time-of-flight mass spectrometry
  • desorption mass spectrometry
  • desorption spectrometry
  • desorption time-of-flight mass spectrometry
  • dilution mass spectrometry
  • dispersive x-ray spectrometry
  • dissociation tandem mass spectrometry
  • electron ionization mass spectrometry
  • electrospray ion trap mass spectrometry
  • electrospray ionisation mass spectrometry
  • electrospray ionisation tandem mass spectrometry
  • electrospray ionization fourier transform ion cyclotron resonance mass spectrometry
  • electrospray ionization mass spectrometry
  • electrospray ionization tandem mass spectrometry
  • electrospray ionization time-of-flight mass spectrometry
  • electrospray ionization-mass spectrometry
  • electrospray mass spectrometry
  • electrospray tandem mass spectrometry
  • electrospray-ionization mass spectrometry
  • emission spectrometry
  • energy dispersive x-ray spectrometry
  • esi mass spectrometry
  • fab mass spectrometry
  • fast atom bombardment mass spectrometry
  • flame atomic absorption spectrometry
  • flight mass spectrometry
  • flight-mass spectrometry
  • flow tube mass spectrometry
  • fluorescence spectrometry
  • fourier transform infrared spectrometry
  • fourier transform ion cyclotron resonance mass spectrometry
  • fourier transform mass spectrometry
  • fourier-transform ion cyclotron resonance mass spectrometry
  • ftir spectrometry
  • gas chromatography mass spectrometry
  • gas chromatography ratio mass spectrometry
  • gas chromatography-combustion-isotope ratio mass spectrometry
  • gas chromatography-mass spectrometry
  • gas mass spectrometry
  • high-performance liquid chromatography ionization mass spectrometry
  • high-performance liquid chromatography ionization tandem mass spectrometry
  • high-performance liquid mass spectrometry
  • high-performance liquid tandem mass spectrometry
  • high-resolution mass spectrometry
  • imaging mass spectrometry
  • infrared spectrometry
  • inlet mass spectrometry
  • introduction mass spectrometry
  • ion cyclotron resonance mass spectrometry
  • ion flow tube mass spectrometry
  • ion mass spectrometry
  • ion mobility mass spectrometry
  • ion mobility spectrometry
  • ion trap mass spectrometry
  • ion trap tandem mass spectrometry
  • ion-trap mass spectrometry
  • ion-trap tandem mass spectrometry
  • ionisation mass spectrometry
  • ionisation tandem mass spectrometry
  • ionization fourier transform ion cyclotron resonance mass spectrometry
  • ionization fourier transform mass spectrometry
  • ionization imaging mass spectrometry
  • ionization ion trap mass spectrometry
  • ionization mass spectrometry
  • ionization quadrupole time-of-flight tandem mass spectrometry
  • ionization tandem mass spectrometry
  • ionization time-of-flight mass spectrometry
  • ionization-mass spectrometry
  • ionization-tandem mass spectrometry
  • isotope dilution mass spectrometry
  • isotope ratio mass spectrometry
  • laser desorption ionization time-of-flight mass spectrometry
  • laser desorption mass spectrometry
  • laser desorption spectrometry
  • laser desorption time-of-flight mass spectrometry
  • laser ionization mass spectrometry
  • laser ionization time-of-flight mass spectrometry
  • liquid chromatography electrospray ionization mass spectrometry
  • liquid chromatography electrospray ionization tandem mass spectrometry
  • liquid chromatography ion trap mass spectrometry
  • liquid chromatography ionisation mass spectrometry
  • liquid chromatography ionization mass spectrometry
  • liquid chromatography ionization tandem mass spectrometry
  • liquid chromatography mass spectrometry
  • liquid chromatography tandem mass spectrometry
  • liquid chromatography time-of-flight mass spectrometry
  • liquid chromatography-mass spectrometry
  • liquid chromatography-tandem mass spectrometry
  • liquid ion trap mass spectrometry
  • liquid mass spectrometry
  • liquid secondary ion mass spectrometry
  • liquid tandem mass spectrometry
  • magnetic resonance spectrometry
  • maldi mass spectrometry
  • maldi-tof mass spectrometry
  • mass spectrometry
  • matrix-assisted laser desorption ionization time-of-flight mass spectrometry
  • matrix-assisted laser desorption time-of-flight mass spectrometry
  • matrix-assisted laser ionization mass spectrometry
  • matrix-assisted laser ionization time-of-flight mass spectrometry
  • membrane inlet mass spectrometry
  • membrane introduction mass spectrometry
  • mobility mass spectrometry
  • mobility spectrometry
  • multiple-stage mass spectrometry
  • nano-electrospray ionization mass spectrometry
  • negative electrospray ionization tandem mass spectrometry
  • negative ion mass spectrometry
  • nuclear magnetic resonance spectrometry
  • optical emission spectrometry
  • photoionization mass spectrometry
  • plasma atomic emission spectrometry
  • plasma mass spectrometry
  • plasma optical emission spectrometry
  • plasma-mass spectrometry
  • pressure chemical ionization mass spectrometry
  • pressure chemical ionization tandem mass spectrometry
  • pressure photoionization mass spectrometry
  • probe mass spectrometry
  • quadrupole ion trap mass spectrometry
  • quadrupole mass spectrometry
  • quadrupole time-of-flight mass spectrometry
  • quadrupole time-of-flight tandem mass spectrometry
  • quantitative mass spectrometry
  • radical probe mass spectrometry
  • raman spectrometry
  • ratio mass spectrometry
  • reflectance spectrometry
  • resolution mass spectrometry
  • resonance mass spectrometry
  • resonance spectrometry
  • rutherford backscattering spectrometry
  • secondary ion mass spectrometry
  • selected ion flow tube mass spectrometry
  • sensitive liquid tandem mass spectrometry
  • silicon mass spectrometry
  • tandem mass spectrometry
  • time-of-flight mass spectrometry
  • time-of-flight secondary ion mass spectrometry
  • time-of-flight tandem mass spectrometry
  • tof mass spectrometry
  • transform infrared spectrometry
  • transform ion cyclotron resonance mass spectrometry
  • transform mass spectrometry
  • trap mass spectrometry
  • trap tandem mass spectrometry
  • trap-mass spectrometry
  • triple quadrupole mass spectrometry
  • tube mass spectrometry
  • x-ray fluorescence spectrometry
  • x-ray spectrometry

  • Terms modified by Spectrometry

  • spectrometry analysis
  • spectrometry approach
  • spectrometry data
  • spectrometry detection
  • spectrometry determination
  • spectrometry experiment
  • spectrometry imaging
  • spectrometry measurement
  • spectrometry method
  • spectrometry methods
  • spectrometry study
  • spectrometry system
  • spectrometry technique
  • spectrometry techniques
  • spectrometry technology

  • Selected Abstracts


    JOURNAL OF PHYCOLOGY, Issue 5 2010
    Kyra B. Hay
    Measuring qualitative traits of plant tissue is important to understand how plants respond to environmental change and biotic interactions. Near infrared reflectance spectrometry (NIRS) is a cost-, time-, and sample-effective method of measuring chemical components in organic samples commonly used in the agricultural and pharmaceutical industries. To assess the applicability of NIRS to measure the ecologically important tissue traits of carbon, nitrogen, and phlorotannins (secondary metabolites) in brown algae, we developed NIRS calibration models for these constituents in dried Sargassum flavicans (F. K. Mertens) C. Agardh tissue. We then tested if the developed NIRS models could detect changes in the tissue composition of S. flavicans induced by experimental manipulation of temperature and nutrient availability. To develop the NIRS models, we used partial least squares regression to determine the statistical relationship between trait values determined in laboratory assays and the NIRS spectral data of S. flavicans calibration samples. Models with high predictive power were developed for all three constituents that successfully detected changes in carbon, nitrogen, and phlorotannin content in the experimentally manipulated S. flavicans tissue. Phlorotannin content in S. flavicans was inversely related to nitrogen availability, and nitrogen, temperature, and tissue age interacted to significantly affect phlorotannin content, demonstrating the importance of studies that investigate these three variables simultaneously. Given the speed of analysis, accuracy, small tissue requirements, and ability to measure multiple traits simultaneously without consuming the sample tissue, NIRS is a valuable alternative to traditional methods for determining algal tissue traits, especially in studies where tissue is limited. [source]


    ARCHAEOMETRY, Issue 6 2009
    F. J. M. RUTTEN
    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used, for the first time, for the characterization of opaque ancient glasses. Isotope-specific chemical imaging with sub-micron resolution enabled the separate analysis of opacifiying inclusions and the surrounding glass matrix. Phase identification has been demonstrated and quantification of the matrix composition has been investigated by use of Corning Glass Standard B as a model. Trace element detection limits are typically in the range 0.5,5.0 ppm atomic,in favourable cases down to 0.01 ppm. For the analysis of inclusions in particular, this has the potential to provide new information of use in establishing provenance and trade routes by ,fingerprinting' as well as the investigation of manufacturing techniques, as demonstrated by comparisons between glasses and with EDX data from the same samples. [source]


    ARCHAEOMETRY, Issue 4 2009
    C. MATHE
    Four Nabataean samples collected in some of the monumental tombs of Madâ'in Sâlih, ancient Hegra, in Saudi Arabia, have been studied by gas chromatography coupled with mass spectrometry. These samples are textile fragments that are either covered with a black layer or bound together with some black amorphous substance. Fatty acids and triterpenoic compounds were detected. Eight triterpenic compounds were identified: ursa-9(11),12-dien-3-ol, ursa-9(11),12-dien-3-one, olean-9(11),12-dien-3,-ol, ,-amyrone, ,-amyrin, ,-amyrone, ,-amyrin and lupeol. The resinous chemical composition and these pentacyclic alcohols, in considerable proportion, indicate a resin of the Burseraceae family, possibly of the genus Canarium. [source]

    A Comparison of Membrane Inlet Mass Spectrometry and Nitric Oxide (NO) Electrode Techniques to Detect NO in Aqueous Solution

    ELECTROANALYSIS, Issue 4 2010
    Chingkuang Tu
    Abstract The NO electrode and membrane inlet mass spectrometry (MIMS) have the advantage of being sensitive, direct, and real time detectors of NO in aqueous solution. They do not require reacting NO with labels or purging of NO with an inert gas. We show that the NO electrode and MIMS are comparable in sensitivity detecting NO concentrations to 0.5,nM in aqueous solution, and both give identical results in a biological measurement, the reactions of deoxyhemoglobin with nitrite. [source]

    Speciation and Environmental Fate of Chromium in Rivers Contaminated with Tannery Effluents

    J. Dominik
    Abstract Redox and size speciation of chromium in rivers contaminated with tannery wastewater was carried out to provide insight into its transport and removal mechanisms. Total chromium was determined with Inductively Coupled Plasma-Mass Spectrometry and Cr,(VI) with Catalytic Adsorption Stripping Voltammetry. For the size speciation, particles were retained with a cartridge filter (cut-off 1.2,,m) and the total filterable fraction was further fractionated with Tangential Flow Filtration to determine the concentrations of chromium associated with the High Molecular Weight Colloidal (HMWC), Low Molecular Weight Colloidal (LMWC) and Truly Dissolved (TD) fractions. Two fluvial systems of similar sizes, but located in contrasting climatic zones, were selected for comparison: the Sebou-Fez system in Morocco and Dunajec River-Czorsztyn Reservoir system in Poland. Particulate Cr dominated in the Sebou-Fez system (about 90,%); while in the Dunajec-Czorsztyn system, it represented only 17,53,% of the total chromium in raw water. Still, the partition coefficients [Kd] were of the same magnitude. Chromium,(III) was the only form detected in Sebou-Fez, whereas in Dunajec-Czorsztyn Cr,(VI) was also present with its proportion increasing downstream from the input of tannery wastewater due to the preferential removal of Cr,(III). In the filtered water in Morocco a large fraction of Cr occurred in the HMWC fraction (50,70,%) at the two most contaminated sites, while the LMWC and TD forms prevailed at the non-contaminated sites in the Sebou River. At a very high concentration, in the water in the proximity of tanneries (well above the theoretical saturation level) Cr precipitated as polynuclear Cr-hydroxide. In Dunajec-Czorsztyn, the partition of Cr,(III) was approximately equal between the HMWC, LMWC and TD fractions, in contrast to Cr,(VI) which occurred almost exclusively in the TD fraction. In both systems, Cr,(III) was rapidly removed from the water to the sediments. The confluence of the Sebou with the Fez and the Czorsztyn reservoir trapped efficiently Cr,(III) preventing its spreading over long distances. Cr,(VI) showed conservative behavior and bypassed the Czorsztyn Reservoir. This study provides a first set of data on the partitioning of Cr,(III) and Cr,(VI) between the particulate, the colloidal and truly dissolved fractions in fluvial systems contaminated with tannery effluents. It also suggests that, in these systems, truly dissolved Cr,(III) can be adequately modeled from the total filterable concentrations. [source]

    Accumulation of toxic metals (Pb and Cd) in the sea urchin Diadema aff. antillarum Philippi, 1845, in an oceanic island (Tenerife, Canary Islands)

    Ofelia Dolores Hernández
    Abstract This document shows the results obtained from a study on the concentration of toxic heavy metals in the internal tissue and exoskeleton of sea urchins, collected from their natural habitat. The levels of lead and cadmium were measured by Graphite Furnace Atomic Absorption Spectrometry. The mean concentrations of lead and cadmium in the internal tissue were 304.04 and 260.54 ,g/kg respectively, whereas in the shell they were 185.02 and 142.48 ,g/kg. We also performed a statistical analysis of the differences in the distribution of metals between their exoskeleton and their internal content, a correlation study of the metal content in internal tissue and shell and sampling areas, and a correlation study between the metal content and sample size. Since the sea urchin Diadema antillarum presents a wide range of variation in metal content, this study suggests that this species is an excellent bioindicator of heavy metal contamination. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source]

    Structure-Dependent Electrochemical Behavior of Thienylplatinum(II) Complexes of N,N-Heterocycles

    Feng Zhao
    Abstract trans -[Pt(MeCN)(PPh3)2(2-thienyl)]BF4 (1) serves as a convenient precursor to bifunctional mononuclear trans -[Pt(PPh3)2(,1 - N - N)(2-thienyl)]BF4 [N - N = pyrazine (2); 2-chloropyrazine, (3)] and dinuclear trans,trans -[Pt2(PPh3)4(,- N - N)(2-thienyl)2](BF4)2 [(N - N = 4,4, -bipyridine (4); 4,4, -vinylenedipyridine (5)] complexes. The nuclear selectivity is conveniently controlled by the choice of the heterocyclic ligands or spacers. Both structural types 3 and 5 were confirmed by single-crystal X-ray crystallographic analyses. Their solution identities were established by positive-ion Electrospray Mass Spectrometry (ESMS). The electroactivities of these complexes were studied by cyclic voltammetry (CV). Continuous CV scans of 4 and 5 revealed variations in the redox waves with the number of scans. While the initial oxidative scan exhibited only a broad, irreversible wave, further cycling showed the growth of two additional redox couples up to about the tenth cycle. The peak currents of these redox couples began to decay with prolonged potential cycling beyond the tenth cycle. These findings are consistent with the formation of electroactive oligomers/polymers, and this conclusion is supported by visible thin film formation on the electrodes. In contrast, the mononuclear complexes (2 and 3) do not show such behavior. The films formed were further studied by repetitive potential cycling and XPS. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Reduction of [(C5Me5)2Mo2O5] and [(C5Me5)2Mo2O4] in Methanol/Water/Trifluoroacetate Solutions Investigated by Combined On-Line Electrochemistry/Electrospray-Ionization Mass Spectrometry

    Jenny Gun
    Abstract Complexes [Cp*2Mo2O5] (Cp* = ,5 -C5Me5) and [Cp*2Mo2O4] were investigated by combined on-line electrochemical (EC) reduction and electrospray-ionization mass spectrometry (ESI-MS) techniques in a trifluoroacetic acid buffered water/methanol solution. The reduction products at the larger negative potentials are identical for both compounds. The studies reveal the existence of a wide range of previously unknown di- and trinuclear MoV, MoIV, MoIII, and mixed-valence complexes that were identified on the basis of their masses and characteristic isotope patterns. The structures of the initial compounds and the product of electroreduction with m/z = 713,729 were supported by in situ MSn experiments that allowed the elucidation of the fragmentation pathway for the collision-induced dissociation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    The importance of scent and nectar filters in a specialized wasp-pollination system

    FUNCTIONAL ECOLOGY, Issue 5 2009
    Adam Shuttleworth
    Summary 1.,Plants with open flowers and exposed nectar should attract a wide diversity of flower visitors, yet, for reasons that are not yet well understood, some plants with these ,generalist' floral traits have highly specialized pollination systems. 2.,We investigated this problem in the African milkweed Pachycarpus grandiflorus which has open flowers that produce copious amounts of exposed and concentrated nectar, yet is visited almost exclusively by spider-hunting wasps in the genus Hemipepsis. 3.,These wasps were the only visitors found to consistently carry pollinaria and a cage experiment showed that they are capable of successfully pollinating this plant. Furthermore, experimental hand-pollinations showed that P. grandiflorus is genetically self-incompatible and thus reliant on pollinators for seed set. 4.,We investigated the roles of chemical (nectar and floral scent) and spectral properties in the selective attraction of wasps and the filtering out of other potential flower visitors. Nectar palatability experiments showed that the nectar is unpalatable to honeybees but palatable to the wasps. Choice experiments conducted in the field and using a Y-maze in the laboratory showed that wasps are attracted primarily by scent rather than visual cues. Analysis of scent using Gas Chromatography-Mass Spectrometry showed that these inflorescences produce 36 different compounds, mostly monoterpenes and aliphatics. Analysis of spectral reflectance showed that flowers have similar colouring to the background vegetation. 5.,We conclude that P. grandiflorus is specialized for pollination by Hemipepsis wasps, and in the absence of morphological filters, achieves specialization through unpalatable nectar, cryptic colouring and scent as a selective pollinator attractant. 6.,This study demonstrates that plants whose flowers are not morphologically adapted to exclude particular floral visitors can achieve specialization through non-morphological filters. [source]

    Private channel: a single unusual compound assures specific pollinator attraction in Ficus semicordata

    FUNCTIONAL ECOLOGY, Issue 5 2009
    Chun Chen
    Summary 1.,Floral scents have been suggested to play a key role in the obligate pollination mutualism between figs and fig wasps. However, few studies have determined whether pollinator-attractive compounds could alone assure species-specificity (,private channel'), or whether specificity is mediated by more complex ,floral filters', of which scent is only one component. 2.,We examined changes in the floral volatile compounds of Ficus semicordata, a dioecious fig species, during and after pollination using headspace collection and compound identification by Gas Chromatography/Mass Spectrometry (GC/MS). One benzenoid compound, 4-methylanisole, was strongly predominant (94,98%) among the volatile compounds emitted by both male and female receptive figs of F. semicordata, whereas it was totally absent in the volatiles emitted by figs 4 days after pollination, as well as in receptive-stage volatiles emitted by two other sympatric fig species, Ficus racemosa and Ficus hispida. 3.,Bioassays using the specific pollinator of F. semicordata, Ceratosolen gravelyi, in a Y-tube olfactometer showed that 4-methylanisole was attractive to C. gravelyi in a wide range of concentrations (from 1·22 × 10,2 ng/100 ,L to 1·22 × 106ng/100,L). Moreover, chemical blends lacking 4-methylanisole were unattractive to C. gravelyi. These non-active odour sources included volatile compounds emitted by receptive figs of the two other sympatric fig species and volatiles of F. semicordata post-pollination figs. 4.,All these results suggest that 4-methylanisole is the main signal compound in the floral scent of F. semicordata that attracts its obligate pollinator to the host figs at the precise stage required for pollination and oviposition. Furthermore, the high proportion of 4-methylanisole in the odours of receptive figs of both sexes was consistent with the hypothesis of chemical mimicry in dioecious figs. 5.,A simple signal comprised of one compound that is unusual among Ficus and that is an infrequent, usually minor, component of other floral odours, may thus function as a private channel in this specialized obligate mutualism. [source]

    Sample Target Substrates with Reduced Spot Size for MALDI-TOF Mass Spectrometry Based on Patterned Self-Assembled Monolayers

    Nicole Herzer
    Abstract The wetting properties of structured self-assembled monolayers are used to fabricate sample target substrates for MALDI-TOF mass spectrometry. Combining the advantages of a hydrophobic-hydrophilic surface pattern and the possibility of obtaining micrometer patterns allows an increase in the sensitivity of MALDI-TOF mass spectrometry analysis and a reduction in the traceable concentration down to fmol µL,1. This easy, cheap and fast patterning process provides substrates that allow sensitive, high-resolution mass spectrometry of dilute solutions. [source]

    Simultaneous Determination of Fluorine, Chlorine, Bromine and Iodine in Six Geochemical Reference Materials Using Pyrohydrolysis, Ion Chromatography and Inductively Coupled Plasma-Mass Spectrometry

    Hélène Balcone-Boissard
    halogènes; pyrohydrolyse; chromatographie ionique; spectrométrie de masse couplée à une source de plasma induit; matériaux géologiques de référence Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma-mass spectrometry for Br and I. The detection limits in solutions were 100 ,g l,1 for both F and Cl and 10 ng l,1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg,1 for F and Cl and 2 ,g kg,1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg,1 for F and Cl, 100 ,g kg,1 for Br and 25 ,g kg,1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites , the powders of which were heterogeneous in halogens at the 500 mg level. Les concentrations en halogènes (fluor, chlore, brome et iode) on été déterminées dans 6 matériaux géologiques de référence (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2), distribués par le GSJ, l'USGS et le CRPG. Les halogènes étaient d'abord extraits des échantillons, disponibles sous forme de poudre, par pyrohydrolyse. F et Cl sont ensuite analysés par chromatographie ionique, Br et I par spectrométrie de masse couplée à une source de plasma induit. Les limites de détection sont de 100 ,g l,1 pour F et Cl, et de 10 ng l,1 pour Br et I, respectivement. L'extraction des halogènes était réalisée sur 500 mg de poudre de roche, produisant 100 ml de solution d'extraction. Ainsi, pour les échantillons de roche, les limites de détection étaient de 20 mg kg,1 pour F et Cl, et 2 ,g kg,1 pour Br et I. L'erreur analytique moyenne sur la gamme de concentration étudiée est estimée à 10 mg kg,1 pour F et Cl, 100 ,g kg,1 pour Br et 25 ,g kg,1 pour I. Les valeurs de concentrations données, obtenues par l'analyse répétée (> 10) du même échantillon étaient en accord avec les valeurs reportées dans la littérature. Elles présentent en général une plus faible dispersion autour de la valeur moyenne. Dans le cas d'une importante dispersion des résultats, celle-ci est discutée en terme d'hétérogénéité de l'échantillon analysé et de contamination durant la préparation du matériel de référence. Les échantillons de référence de composition basaltique se révèlent être plus appropriés pour étudier les compositions en halogènes que les matériaux correspondant à des roches différenciées, en particulier des granites dont la distribution en halogènes apparaît hétérogène dans les poudres à l'échelle d'un aliquot de 500 mg. [source]

    Comparison of Linear Regression Models for Quantitative Geochemical Analysis: An Example Using X-Ray Fluorescence Spectrometry

    Mirna Guevara
    calibration analytique; régression linéaire; matériaux de référence en géochimie; géochimie analytique; loi de propagation d'erreurs This paper presents statistical aspects related to the calibration process and a comparison of different regression approaches of relevance to almost all analytical techniques. The models for ordinary least-squares (OLS), weighted least-squares (WLS), and maximum likelihood fitting (MLF) were evaluated and, as a case study, X-ray fluorescence (XRF) calibration curves for major elements in geochemical reference materials were used. The results showed that WLS and MLF models were statistically more consistent in comparison with the usually applied OLS approach. The use of uncertainty on independent and dependent variables during the calibration process and the calculation of final uncertainty on individual results using error propagation equations are the novel aspects of our work. Cet article présente les aspects statistiques liés au processus de calibration et fait une comparaison des différents calculs de régression utilisés dans pratiquement toutes les techniques analytiques. Les modèles des moindres carrés ordinaires (MCO) et pondérés (MCP), et d'ajustement de maximum de vraisemblance (AMV) ont étéévalués et appliqués aux courbes de calibration d'éléments majeurs obtenues en analyse par fluorescence X (XRF) de matériaux certifiés de référence. Les résultats obtenus avec les modèles MCP et AMV sont plus cohérents statistiquement que ceux obtenus la méthode classique des MCO. L'utilisation de l'incertitudes sur des variables indépendantes ou dépendantes durant la procédure de calibration et le calcul de l'incertitude finale sur chaque résultat à partir des lois de propagation d'erreur sont des aspects novateurs de ce travail. [source]

    Accurate U-Pb Age and Trace Element Determinations of Zircon by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

    Honglin Yuan
    LA-ICP-MS; laser excimer; zircon; géochronologie; éléments en trace Various zircons of Proterozoic to Oligocene ages (1060-31 Ma) were analysed by laser ablation-inductively coupled plasma-mass spectrometry. Calibration was performed using Harvard reference zircon 91500 or Australian National University reference zircon TEMORA 1 as external calibrant. The results agree with those obtained by SIMS within 2s error. Twenty-four trace and rare earth elements (P, Ti, Cr, Y, Nb, fourteen REE, Hf, Ta, Pb, Th and U) were analysed on four fragments of zircon 91500. NIST SRM 610 was used as the reference material and 29Si was used as internal calibrant. Based on determinations of four fragments, this zircon shows significant intra-and inter-fragment variations in the range from 10% to 85% on a scale of 120 ,m, with the variation of REE concentrations up to 38.7%, although the chondrite-normalised REE distributions are very similar. In contrast, the determined age values for zircon 91500 agree with TIMS data and are homogeneous within 8.7 Ma (2s). A two-stage ablation strategy was developed for optimising U-Pb age determinations with satisfactory trace element and REE results. The first cycle of ablation was used to collect data for age determination only, which was followed by continuous ablation on the same spot to determine REE and trace element concentrations. Based on this procedure, it was possible to measure zircon ages as low as 30.37 0.39 Ma (MSWD = 1.4; 2s). Other examples for older zircons are also given. Différents zircons d'âges variant du Protérozoïque à l'Oligocène (1060-31 Ma) ont été analysés par spectrométrie avec source à plasma induit et ablation laser. La calibration a été faite en utilisant le zircon 91500 de référence de Harvard ou le zircon TEMORA 1 de référence de l'Université Nationale Australienne comme calibrant externe. Les résultats sont en accord avec ceux obtenus par SIMS aux erreurs analytiques près (2s). Vingt-quatre éléments en trace et Terres Rares (P, Ti, Cr, Y, Nb, quatorze ETR, Hf, Ta, Pb, Th et U) ont été analysés sur quatre fragments du zircon 91500. Le standard SRM 610 de NIST a été utilisé comme matériau de référence et 29Si comme calibrant interne. À partir des déterminations faites sur ces quatre fragments, ce zircon montre des variations intra et inter fragments de l'ordre de 10%à 85%à une échelle de 120 ,m, avec des variations des concentrations de Terres Rares allant jusquà 38.7%, bien que le spectre de Terres Rares normalisé aux chondrites reste très constant. Au contraire, les âges déterminés pour le zircon 91500 sont en accord avec les résultats de TIMS et sont homogènes à 8.7 Ma près (2s). Une stratégie d'ablation en deux étapes a été développée pour optimiser les déterminations d'âges U-Pb, et avoir des résultats de Terres Rares et d'éléments en trace satisfaisants. Le premier cycle d'ablation était utilisé pour collecter les données nécessaires à la détermination de l'âge seulement et était suivi d'un cycle d'ablation continue sur le même spot, pour déterminer les concentrations en Terres Rares et en éléments en trace. Grâce à cette procédure, il a été possible de mesurer des âges sur zircons aussi récents que 30.37 0.39 Ma (MSWD = 1.4; 2s). D'autres exemples sur des zircons plus vieux sont aussi donnés. [source]

    Determination of Lithium Contents in Silicates by Isotope Dilution ICP-MS and its Evaluation by Isotope Dilution Thermal Ionisation Mass Spectrometry

    Takuya Moriguti
    Lithium; ICP-MS avec dilution isotopique; TIMS; matériaux silicatés de référence; météorites A precise and simple method for the determination of lithium concentrations in small amounts of silicate sample was developed by applying isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS). Samples plus a Li spike were digested with HF-HClO4, dried and diluted with HNO3, and measured by ICP-MS. No matrix effects were observed for 7Li/6Li in rock solutions with a dilution factor (DF) of 97 at an ICP power of 1.7 kW. By this method, the determination of 0.5 ,g g -1 Li in a silicate sample of 1 mg can be made with a blank correction of < 1%. Lithium contents of ultrabasic to acidic silicate reference materials (JP-1, JB-2, JB-3, JA-1, JA-2, JA-3, JR-1 and JR-2 from the Geological Survey of Japan, and PCC-1 from the US Geological Survey) and chondrites (three different Allende and one Murchison sample) of 8 to 81 mg were determined. The relative standard deviation (RSD) was typically < 1.7%. Lithium contents of these samples were further determined by isotope dilution-thermal ionisation mass spectrometry (ID-TIMS). The relative differences between ID-ICP-MS and ID-TIMS were typically < 2%, indicating the high accuracy of ID-ICP-MS developed in this study. Nous avons développé une méthode simple et précise de détermination des concentrations en lithium dans de très petits échantillons silicatés. Elle est basée sur la méthode de dilution isotopique couplée à l'analyse par spectrométrie de masse avec couplage induit (ID-ICP-MS). Les échantillons auxquels est ajouté le spike de Li, sont mis en solution avec un mélange HF-HclO4, évaporés à sec, puis repris avec HNO3 et analysés à l'ICP-MS. Aucun effet de matrice n'est observé sur les rapports 7Li/6Li dans les solutions quand les facteurs de dilution sont 97 et qu'elles sont analysées avec une puissance du plasma de 1.7 kW. Par cette méthode, la détermination de 0.5 ,g g -1 de Li dans un échantillon silicaté de 1 mg peut être effectuée avec une correction de blanc < 1 %. Les teneurs en lithium des matériaux de référence de composition ultrabasique à acide (JP-1, JB-2, JB-3, JA-1, JA-2, JA-3, JR- 1 et JR-2 du Service Géologique du Japon, et PCC-1 du Service Géologique des USA) et de chondrites (trois échantillons différents d'Allende et un de Murchison), de poids variant entre 8 et 81 mg ont été déterminées. La déviation standard relative typique était < 1.7%. Les teneurs en lithium de ces échantillons ont été ensuite mesurées par dilution isotopique et spectrométrie de masse à thermo-ionisation (ID-TIMS). Les différences entre les résultats obtenus par ID-ICP-MS et ID-TIMS étaient < 2%, démontrant ainsi la grande justesse de la technique ID-ICP-MS développée dans cette étude. [source]

    Molybdenum Concentrations Measured in Eleven USGS Geochemical Reference Materials by Isotope Dilution Thermal Ionisation Mass Spectrometry

    Michael E. Wieser
    molybdène; dilution isotopique; spectrométrie de masse à; thermo-ionisation; matériaux de référence USGS Molybdenum concentrations in eleven USGS geochemical reference materials AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 and W-2 were measured by isotope dilution thermal ionisation mass spectrometry (ID-TIMS). In every case but one, the concentrations determined in this study were significantly lower than the current consensus values. Molybdenum concentrations determined by ID-TIMS are inherently more accurate and precisions may be up to an order of magnitude higher than those measured by other analytical techniques. Les concentrations en molybdène de onze matériaux géochimiques de référence de l'USGS, AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 et W-2, ont été mesurées par dilution isotopique et spectrométrie de masse à thermo-ionisation (ID-TIMS). Dans tous les cas sauf un, les concentrations déterminées dans cette étude sont nettement inférieures aux valeurs généralement admises. Les concentrations en molybdène déterminées par ID-TIMS sont par définition plus exactes et leur précision analytique peut tre améliorée d'un ordre de grandeur par rapport à celle déterminée par d'autres techniques analytiques. [source]

    Classification of cancer types by measuring variants of host response proteins using SELDI serum assays

    Eric T. Fung
    Abstract Protein expression profiling has been increasingly used to discover and characterize biomarkers that can be used for diagnostic, prognostic or therapeutic purposes. Most proteomic studies published to date have identified relatively abundant host response proteins as candidate biomarkers, which are often dismissed because of an apparent lack of specificity. We demonstrate that 2 host response proteins previously identified as candidate markers for early stage ovarian cancer, transthyretin and inter-alpha trypsin inhibitor heavy chain 4 (ITIH4), are posttranslationally modified. These modifications include proteolytic truncation, cysteinylation and glutathionylation. Assays using Surface Enhanced Laser Desorption/Ionization Time of Flight Mass Spectrometry (SELDI-TOF-MS) may provide a means to confer specificity to these proteins because of their ability to detect and quantitate multiple posttranslationally modified forms of these proteins in a single assay. Quantitative measurements of these modifications using chromatographic and antibody-based ProteinChip® array assays reveal that these posttranslational modifications occur to different extents in different cancers and that multivariate analysis permits the derivation of algorithms to improve the classification of these cancers. We have termed this process host response protein amplification cascade (HRPAC), since the process of synthesis, posttranslational modification and metabolism of host response proteins amplifies the signal of potentially low-abundant biologically active disease markers such as enzymes. © 2005 Wiley-Liss, Inc. [source]

    Volatile composition and proteolysis in traditionally produced mature Kashar cheese

    Ali Adnan Hayaloglu
    Summary Twelve samples of raw milk mature Kashar cheese at different stages of ripening were collected from retail outlets. The average pH, moisture, fat-in-dry matter, protein, salt-in-dry matter and titratable acidity contents of the samples were 5.33, 39.39%, 45.20%, 27.33%, 6.62% and 0.65% (as lactic acid), respectively. Indices of proteolysis varied from 10.72% to 23.75% and 7.09% to 12.26% for pH 4.6-soluble and 12% trichloroacetic acid-soluble nitrogen fractions, respectively, and total free amino acid concentrations ranged from 6.36 to 36.03 mg Leu g,1 of cheese. The cheeses were analysed for volatile compounds by Solid Phase Microextraction and Gas Chromatography-Mass Spectrometry (GC-MS). A total of 113 compounds were detected and identified belonging to the following chemical groups: acids (eleven), esters (sixteen), ketones (sixteen), aldehydes (six), alcohols (twenty-seven), sulphur compounds (seven), terpenes (seven) and miscellaneous compounds (twenty-three). The potential effect of each compound on the flavour profile of Kashar cheese is discussed. Acids, esters, ketones and alcohols were found at considerable levels in the samples. Kashar cheeses obtained from different retail outlets displayed some differences in terms of chemical composition, proteolysis and patterns of aroma compounds; and may be attributed to their production technologies and age-related variations. [source]

    Identification of Modified Proteins by Mass Spectrometry

    IUBMB LIFE, Issue 2 2002
    Albert Sickmann
    Abstract Because it is obvious that high-throughput genomics do not lead to a molecular description or even a prediction of protein function, modern techniques for protein analysis become increasingly more important. Sequence analysis of proteins and peptides is not limited to the elucidation of the primary structure of a protein. The analysis of posttranslational modifications is an important task of protein chemistry in proteome research. Increased sensitivity in mass spectrometry as a result of more efficient ionization techniques and better detection systems has allowed the stepwise reduction of protein quantity for analysis. Protein spots of 2D-PAGE separated samples are now sufficient for an unequivocal identification of a protein by mass spectrometry. In addition to protein identification, a closer look at posttranslational modifications is now also possible. It is assumed that modifications such as phosphorylation or glycosylation exist on every second protein and that they are important for the protein function. [source]

    An automated method for peak detection and matching in large gas chromatography-mass spectrometry data sets

    JOURNAL OF CHEMOMETRICS, Issue 8-10 2006
    Sarah J. Dixon
    Abstract A new approach for peak detection and matching has been developed and applied to two data sets. The first consisted of the Gas Chromatography-Mass Spectrometry (GC-MS) samples of 965 human sweat samples obtained from a population of 197 individuals. The second data set contained 500 synthetic chromatograms, and was generated to validate the peak detection and matching methods. The size of both of the data sets (around 500,000 detectable peaks over all chromatograms in data set 1, and around 100,000 in data set 2) would make it unfeasible to check manually whether peaks are matched. In the method described, the first procedure involves pre-processing the data before carrying out the second procedure of peak detection. The final procedure of peak matching consists of three stages: (a) finding potential target peaks in the full data set over all chromatograms; (b) matching peaks in the chromatograms to these targets to form clusters of spectra associated with each target; (c) merging targets where appropriate. Peak detection and matching were applied to both data sets, and the importance of stage (c) of peak matching described. In addition to the analysis of the synthetic chromatograms, the method was also validated by shuffling the original order of the sweat chromatograms and performing the methods independently on the newly shuffled data. Copyright © 2007 John Wiley & Sons, Ltd. [source]


    The aim of this study was to assess the proteolytic activity of Lactobacillus sakei (DSM 6333), L. plantarum (B21), and to a lesser extent, L. farciminis (DSM 20184) on meat sarcoplasmic proteins. The protein composition was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and capillary electrophoresis after incubation of meat extract inoculated with bacteria. All strains showed proteolytic activity: a band about 94 kDa disappeared in samples inoculated with L. farciminis and L. plantarum and strongly decreased in those inoculated with L. sakei. The intensity of the bands with a molecular weight between 94 and 38 kDa decreased in all samples. Capillary electrophoresis analysis ascertained the disappearance of the fractions corresponding to 8.64 and 8.66 min retention time in all samples. The bands corresponding to 94 kDa and 38 kDa were, respectively, identified as glycogen phosphorylase muscle isoform and glyceraldehyde 3-phosphate dehydrogenase, by in situ digestion of protein gel bands and peptide map analysis using Matrix Assisted Laser Desorption/Ionization - Time of Flight Mass Spectrometry (MALDI-TOF MS). [source]


    ABSTRACT The content of quinolizidine alkaloids (QA) in Lupinus campestris, Fabaceae family, was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), Samples of various organs of Lupinus campestris collected at different monthly stages of the growing plant, were subjected to extraction in a Merck Extrelut column. The quinolizidine alkaloid patterns of stems, leaves, flowers, pods and seeds were assessed and then identified and quantified by GC. Alkaloid structures were identified according to their mass fragmentation patterns, in combination with their indicative Kovats retention index. Alkaloids found in several developmental stages of the plant were mainly: aphyllidine, 5, 6-dehydrolupanine, aphylline, dehydro-oxosparteine, lupanine, ,-isolupanine, hydroxyaphylline and hydroxyaphyllidine, plus two alkaloids that -were not identified. During the third month the relative abundance of total alkaloids were highest. The main alkaloids found in seeds were hydroxyaphylline and hydroxyaphyllidine. [source]

    Analysis of Volatile Compounds in Beef Fat by Dynamic-Headspace Solid-Phase Microextraction Combined with Gas Chromatography,Mass Spectrometry

    A. Watanabe
    ABSTRACT:, A solid-phase microextraction (SPME) technique has been applied to the determination of the volatile compounds, including diterpenoids and lactones, in cooked beef fat. The ability of static-headspace SPME to extract lactones was disappointing, regardless of the type of SPME fiber or the temperature used. Dynamic-headspace SPME extraction with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C, by contrast, enabled the analysis of volatiles, including delta-lactones, gamma-lactones, and diterpenoids, with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C. Fifty-three compounds were identified from only 0.20 g of rendered beef fat, and 76% of these showed reliable peak size repeatability: the coefficient of variation was less than 10% on the total ion chromatograms obtained from gas chromatography,mass spectrometry (GC,MS) analysis. Some lactones showed higher CV values (>10%), but single-ion mode GC,MS analysis reduced them to 10% or less. In a study of beef samples available to the Japanese market, our analytical procedure revealed significantly higher levels of 1-hexanol, octadecane, ethyl tetradecanoate, gamma-nonalactone, but lower levels of delta-decalactone, delta-dodecalactone, and neophytadiene, in Japanese Black cattle than in beef imported from Australia. [source]

    Trace Elemental Analysis of Titanium Dioxide Pigments and Automotive White Paint Fragments for Forensic Examination Using High-Energy Synchrotron Radiation X-Ray Fluorescence Spectrometry,

    Yoshinori Nishiwaki M.S.
    Abstract:, High-energy synchrotron radiation x-ray fluorescence spectrometry (SR-XRF) utilizing 116 keV x-rays was used to characterize titanium dioxide pigments (rutile) and automotive white paint fragments for forensic examination. The technique allowed analysis of K lines of 9 trace elements in 18 titanium dioxide pigments (rutile), and 10 trace elements in finish coat layers of seven automotive white paint fragments. High-field strength elements (HFSE) were found to strongly reflect the origin of the titanium dioxide (TiO2) pigments, and could be used as effective parameters for discrimination and classification of the pigments and paint fragments. A pairwise comparison of the finish coat layers of seven automotive white paint fragments was performed. The trace elements in the finish coat layers detected by the high-energy SR-XRF were especially effective for identification. By introducing the trace element information of primer and electrocoat layers, all the automotive white paint fragments could be discriminated by this technique. [source]

    Age Determination of Ballpoint Pen Ink by Thermal Desorption and Gas Chromatography,Mass Spectrometry,

    Jürgen H. Bügler Ph.D.
    Abstract:, Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography,mass spectrometry (GC,MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. [source]

    Detection of Explosives in Hair Using Ion Mobility Spectrometry

    Jimmie C. Oxley Ph.D.
    Abstract:, Conventional explosives 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), and ethylene glycol dinitrate (EGDN) sorbed to hair can be directly detected by an ion mobility spectrometer (IMS) in E-mode (for explosives). Terrorist explosive, triacetone triperoxide (TATP), difficult to detect by IMS in E-mode, was detected in N-mode (for narcotics). Three modes of sample introduction to IMS vapor desorption unit were used: (i) placement of hair directly into the unit, (ii) swabbing of hair and placement of swabs (i.e., paper GE-IMS sample traps) into the unit, and (iii) acetonitrile extracts of hair positioned on sample traps and placed into the unit. TNT, NG, and EGDN were detected in E-mode by all three sample introduction methods. TATP could only be detected by the acetonitrile extraction method after exposure of the hair to vapor for 16 days because of lower sensitivity. With standard solutions, TATP detection in E-mode required about 10 times as much sample as EGDN (3.9 ,g compared with 0.3 ,g). IMS in N-mode detected TATP from hair by all three modes of sample introduction. [source]

    The Detection of Multiply Charged Dyes Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for the Forensic Examination of Pen Ink Dyes Directly from Paper

    Jamie D. Dunn M.S.
    Abstract:, Laser desorption mass spectrometry (LDMS) is emerging as a technique for questioned document examination. Its use is limited to detecting ink dyes that are neutral or singly charged. Several inks contain dyes that are multiply charged and LDMS cannot be employed for their identification. We have successfully detected >20 polyionic dyes that can be used in the manufacture of inks using matrix-assisted laser desorption/ionization (MALDI) MS, directly from paper, with the matrix, 2-(4-hydroxyphenylazo)benzoic acid (HABA), and the additive, diammonium hydrogen citrate (DAHC). For example, Acid Violet 49, a charged dye containing one positively-charged site and two negatively charged sulfonate groups, cannot be detected by LDMS, but forms intact, singly charged ions in the MALDI MS experiment. The method described is also useful for identifying multiply charged dye mixtures that are used in modern pen inks. [source]

    Trace Element Fingerprinting of Australian Ocher Using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) for the Provenance Establishment and Authentication of Indigenous Art,

    Rachel L. Green B.Sc.
    Abstract:, The expansion of indigenous art and the interest it has generated both at a domestic and international level means large monetary transactions are taking place between art galleries or centers and purchasers. As such, an accurate and conclusive method for provenance determination of traditional indigenous artistic materials must be established that can, if necessary, be used to assist in authentication of artworks. Laser ablation inductively coupled plasma mass spectrometry was utilized for elemental differentiation and provenance establishment of ocher samples. This research was used to develop a robust scientific protocol which facilitates definitive and accurate determination of provenance of Australian ochers and the artworks created using them. Analysis of the results obtained through this study show that the trace metal distribution patterns alone appear to be sufficient evidence to establish provenance of specific ochers, although additional differentiation between ocher samples, using major element distribution patterns, was achieved through the utilization of X-ray analytical techniques. [source]

    Identification of Organic Pigments in Automotive Coatings Using Laser Desorption Mass Spectrometry,

    Sylwia Stachura
    ABSTRACT: When one looks at an automotive coating, one sees color due to pigments. Modern organic pigments, with high molar absorptivities, may be only minor components of the mixture. Laser desorption mass spectrometry (LDMS) has been shown to be a useful tool for the analysis of colorants such as pen ink dyes. Here, LDMS is used to determine its utility for the identification of pigments, in simple media and in more complex paints. Small paint chips can be introduced into the LDMS instrument, and when an ultraviolet laser is focused on a portion of a chip, ions representative of the pigment(s) are selectively formed. Some pigments such as quinacridones and copper phthalocyanine are very stable and are desorbed and ionized intact. In contrast, benzimidazolones, which contain some single-skeletal bonds, form fragment ions. This method proves to be sensitive and convenient, as no sample preparation is required. The presence of inorganic pigments in addition to modern organic pigments can be determined, and pigments can be directly identified in actual automotive paint chip samples. [source]

    Provenance Determination of Oriental Porcelain Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS),

    Emma K. Bartle B.Sc.
    ABSTRACT: The sale of fraudulent oriental ceramics constitutes a large proportion of the illegal artifact and antique trade and threatens to undermine the legitimate international market. The sophistication and skill of forgers has reached a level where, using traditional appraisal by eye and hand, even the most experienced specialist is often unable to distinguish between a genuine and fraudulent piece. In addition, current provenancing techniques such as energy-dispersive X-ray fluorescence (EDXRF) spectrometry and thermoluminescence (TL) dating can result in significant damage to the artifact itself. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), a relatively nondestructive analytical technique, has been used for the provenance determination of materials based on geographical origin. The technique requires the production of a laser crater, c. 100 ,m in diameter, which is essentially invisible to the naked eye. Debris from this crater is analyzed using ICP-MS, with the results forming the basis of the provenance establishment protocol. Chinese, Japanese, and English porcelain shards have been analyzed using this protocol and generic isotopic distribution patterns have been produced that enable the provenance establishment of porcelain artifacts to their country of production. Minor variations between elemental fingerprints of artifacts produced in the same country also indicate that it may be possible to further provenance oriental ceramics to a specific production region or kiln site. [source]