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Since the development of atomic spectrometry, trace element and isotopic analysis has been mainly based on the monitoring of atomic spectra and monoionic species. However, according to the literature and considering the current instrumental developments, it seems that some of the remaining challenges in this field can be mitigated via the measurement of molecular spectra or of polyatomic ions. This review discusses recent advances in three of the most important atomic techniques (laser-induced breakdown spectrometry, high-resolution continuum source atomic absorption spectrometry and inductively coupled plasma mass spectrometry) and how the monitoring of such molecules or polyatomic ions containing the target analyte enables attaining better selectivity and opens new ways to determine non-metals and to obtain isotopic information.

The increase in the use of SiO2 nanoparticles (NPs) is raising concern about their environmental and health effects, thus necessitating the development of novel methods for their straightforward detection and characterization. Single particle ICP-mass spectrometry (SP-ICP-MS) is able to provide information on the size of NPs, their particle number density and mass concentration. However, the determination of Si via ICP-MS is strongly hampered by the occurrence of spectral overlap from polyatomic species (e.g., CO+ and N2+). The use of tandem ICP-MS (ICP-MS/MS) enables interference-free conditions to be obtained, even in the most demanding applications. Upon testing several gases, the use of CH3F (monitoring of SiF+, mass-shift approach) and of H2 (monitoring of Si+, on-mass approach) were demonstrated to be the most suitable to overcome the spectral interference affecting ultra-trace Si determination (LoD < 15 ng L-1). By using these approaches, SiO2 NPs (ranging between 80 and 400 nm) can be detected and characterized. For SiO2 NPs > 100 nm, it was possible to provide accurate results in a straightforward way, as the signals they give rise to are well resolved from those of the background. In the case of 80 and 100 nm NPs, the use of a simple deconvolution approach following a Gaussian model was needed to characterize SiO2 NPs apparently showing incomplete distributions as a result of the presence of the background signal. Overall, the methods developed using SP-ICP-MS/MS are sensitive and selective enough for the interference-free determination of Si at ultra-trace levels, also in the form of SiO2 NPs.

Item does not contain fulltext Alkaline phosphatase (ALP), an enzyme involved in mineralization of bone, is incorporated into three hydrogel biomaterials to induce their mineralization with calcium phosphate (CaP). These are collagen type I, a mussel-protein-inspired adhesive consisting of PEG substituted with catechol groups, cPEG, and the PEG/fumaric acid copolymer OPF. After incubation in Ca-GP solution, FTIR, EDS, SEM, XRD, SAED, ICP-OES, and von Kossa staining confirm CaP formation. The amount of mineral formed decreases in the order cPEG > collagen > OPF. The mineral:polymer ratio decreases in the order collagen > cPEG > OPF. Mineralization increases Young's modulus, most profoundly for cPEG. Such enzymatically mineralized hydrogel/CaP composites may find application as bone regeneration materials. 01 augustus 2012

Item does not contain fulltext Interest is growing in the use of hydrogels as bone tissue-engineering (TE) scaffolds due to advantages such as injectability and ease of incorporation of active substances such as enzymes. Hydrogels consisting of gellan gum (GG), an inexpensive calcium-crosslinkable polysaccharide, have been applied in cartilage TE. To improve GG suitability as a material for bone TE, alkaline phosphatase (ALP), an enzyme involved in mineralization of bone by cleaving phosphate from organic phosphate, was incorporated into GG hydrogels to induce mineralization with calcium phosphate (CaP). Incorporated ALP induced formation of apatite-like material on the submicron scale within GG gels, as shown by FTIR, SEM, EDS, XRD, ICP-OES, TGA and von Kossa staining. Increasing ALP concentration increased amounts of CaP as well as stiffness. Mineralized GG was able to withstand sterilization by autoclaving, although stiffness decreased. In addition, mineralizability and stiffness of GG was enhanced by the incorporation of polydopamine (PDA). Furthermore, mineralization of GG led to enhanced attachment and vitality of cells in vitro while cytocompatibility of the mineralized gels was comparable to one of the most commonly used bone substitute materials. The results proved that ALP-mediated enzymatic mineralization of GG could be enhanced by functionalization with PDA.

We investigated the lithophile element budgets of both unequilibrated and equilibrated H chondrites using various in-situ techniques such as μXRF, EPMA, LA-ICP-TOF-MS, etc., addressing the effects of thermal metamorphism on their distributions.

The Kokchetav subduction-collision zone is located in the western part of the ancestral Central Asian Orogenic Belt. This zone is built up by the Precambrian Kokchetav microcontinent which includes a HP-UHP metamorphic belt, and the North Kokchetav tectonic zone (NKTZ) which represents an accretionary complex between the Kokchetav microcontinent and the adjacent Stepnyak island-arc. The entire region is widely intruded by Palaeozoic granitoids which were emplaced after the collision of the Stepnyak island-arc with the Kokchetav microcontinent. We present zircon U-Pb ages and Lu-Hf systematics in zircon to better characterize the tectonic evolution of the Kokchetav subduction-collision zone.The Lu-Hf results indicate that the Kokchetav basement rocks are derived from late Neoarchaean - early Palaeoproterozoic (~. 2.5. Ga) crust. For the granite-gneiss basement of the Kokchetav microcontinent, early Mesoproterozoic (Grenville-age, ~. 1.17-1.14. Ga) zircon U-Pb crystallization ages were obtained. For the NKTZ, two main age-components were recognized: (1) an oldest Mesoproterozoic age-component (~. 1.20-1.05. Ga) similar as for the Kokchetav microcontinental zircons, and (2) a younger Early Cambrian (540-520. Ma) or Late Cambrian - Early Ordovician (~. 490-480. Ma) age-component. Th/U ratios (. 0.1) and are typical of a magmatic protolith. The distinction between both zircon types is supported by characteristic cathodoluminescence images. These results confirm previous observations, indicating early Palaeozoic high-grade metamorphism (~. 540-520. Ma) and collisional deformation (~. 490-480. Ma) of the Mesoproterozoic Kokchetav zone as a result of subduction-accretion and collision of the Stepnyak island-arc to the Kokchetav microcontinent. For two additional samples of the Balkashin granitic complex Early Devonian (~. 415-395. Ma) zircon crystallization ages (magmatic Th/U ratios) were obtained. The occurrence of a Mesozoic xenocryst within these leucogranites may indicate that they were emplaced in a continental-arc setting. Refereed/Peer-reviewed

Polymeermaterialen zijn niet meer weg te denken uit ons dagelijks leven. Hun succes is mede te danken aan de mogelijkheid om additieven toe te voegen aan het materiaal waardoor de eigenschappen, zoals o.m. de hardheid, de thermische weerstand en de rekbaarheid, verbeteren. Er bestaat een brede waaier aan additieven, elk met een specifieke functie. Voor de polymeerindustrie is het bijgevolg noodzakelijk om meer dan 60 elementen zowel kwalitatief als kwantitatief te kunnen bepalen en dit in concentraties gaande van percent tot ppb niveau. Ter ondersteuning van de productontwikkeling, de productiecontrole en het kwaliteitsmanagement is elementanalyse zeer belangrijk. In verschillende sectoren worden bovendien nieuwe normen en reglementeringen aangaande het toevoegen van metalen aan polymeren geïntroduceerd of wordt de bestaande regelgeving verstrengd waardoor accurate controle een absolute must is. Hoewel elementanalyse (bepaling van elementen gaande van H tot U) vaak wordt toegepast in de polymeerindustrie voor de hierboven vermelde redenen, is het zo dat de gebruikte analytische methoden zeer verschillend zijn en binnen de Europese Unie niet geharmoniseerd zijn, laat staan wereldwijd. Bovendien worden de gestelde eisen inzake o.m. detectievermogen en analysesnelheid steeds strenger. Dit alles illustreert het belang van de ontwikkeling van betrouwbare, krachtige en praktische methoden voor de bepaling van additieven in polymeren. Een brede waaier aan digestiemethoden alsook aan spectrometrische technieken kan worden ingezet voor de bepaling van (sporen)elementen in polymeren. De doelstelling van dit werk was de ontwikkeling van adequate methoden voor de bepaling van additieven in polymeermaterialen. Hierbij diende telkens een weloverwogen keuze gemaakt te worden van de aan te wenden monstervoorbereiding, de analysemethode en de monsterintroductie (analyse na voorafgaande monsterdigestie of solid sampling).

This work aimed at studying the isotopic composition of the elements strontium (Sr) and lead (Pb), that are present in low concentrations in a large variety of archaeological artefacts. For isotope ratio analysis, inductively coupled plasma-mass spectrometry (ICP-MS) – a powerful technique for the determination of trace elements and isotope ratios – was used. An analytical strategy was developed, consisting of three key steps: (i) the complete dissolution of a small amount of the (solid) archaeological artefacts making use of concentrated mineral acids, allowing a quantitative recovery for Sr and/or Pb to be obtained, (ii) the isolation of Sr or Pb from its concomitant matrix via extraction chromatography, so that a purified Sr or Pb fraction was obtained and a quantitative recovery for Sr or Pb was established, and (iii) the accurate and precise determination of the isotopic composition of Sr and Pb via single-collector ICP-MS (equipped with one detector) and multi-collector ICP-MS (equipped with an array of detectors). The analytical strategy developed was subsequently applied to three archaeological projects. A first project made use of lead isotopic analysis for provenance determination of metallic artefacts in order to obtain insight into the metal trading network and the trade routes between the Roman Empire and the Indian subcontinent in the period 1st century BC – 2nd century AD. In a second project, lead isotopic analysis allowed to identify the sources of high lead concentrations retrieved in the bone tissue of infants from a Roman settlement. It was shown that the lead present in the infant bone tissue is a mix of lead originating from (i) the process of diagenesis – post-mortem lead exchange between bone and soil – and (ii) lead-enriched food consumed by the mother. A third project aimed at obtaining insight into the heterogeneity of the populations of two grave fields. An explorative study was carried out to distinguish individuals that lived locally and individuals that migrated during their life. For this purpose, the dental tissues (enamel and dentine) of a number of individuals were submitted to strontium isotopic analysis.