Analytical evidence of amorphous microdomains within nitridosilicate and nitridoaluminosilicate single crystals

Single crystals of new nitridosilicates and nitridoaluminosilicates with excellent R values in X-ray investigations were analysed quantitatively using 30 to 60μm single-spot LA-ICP-MS. Significant discrepancies between expected and measured chemical composition could not be explained by the crystallographic data. High spatial resolution analysis using electron probe microanalysis (EPMA, 10μm) leads to the discovery of inhomogeneities in the crystalline material. The application of standard single-spot LA-ICP-MS with a spatial resolution of 30 to 60μm is not suitable for the analysis of these crystals as the existing inhomogeneities dominate and alter the determined concentrations. However, owing to the better detection capabilities, a scanning LA-ICP-MS procedure enables a more representative analysis of single crystals of Ca5Si2Al2N8 than single-spot LA-ICP-MS as a result of a larger sampling volume. It is highly likely that these impurities consist of amorphous, vitreous phases as powder diffraction X-ray data indicates the existence of a significant fraction of an X-ray amorphous material besides crystalline silicates. These microdomains contain less aluminium, silicon and calcium or are nearly free of aluminium, which explains the detected discrepancies in the chemical compositio

Phlogopite/matrix, Cpx/matrix and Cpx/phlogopite trace element partitioning in true lamprophyres

This contribution summarizes the results of pilot determination of distribution coefficients for various trace elements between the phlogopite, clinopyroxene and surrounding matrix of calc-alkaline lamprophyres. Partition coefficients were determined using the method of laser ablation in conjunction with inductively coupled plasma-mass spektrometry (LA-ICP-MS).Příspěvek shrnuje výsledky pilotního stanovení rozdělovacích koeficientů pro jednotlivé stopové prvky mezi flogopitem, klinopyroxenem a okolní matrix vápenato-alkalických lamprofyrů. Rozdělovací koeficienty byly určeny s využitím metody laserové ablace ve spojení s hmotnostní spektrometrií indukčně vázaného plazmatu (LA-ICP-MS).This contribution summarizes the results of pilot determination of distribution coefficients for various trace elements between the phlogopite, clinopyroxene and surrounding matrix of calc-alkaline lamprophyres. Partition coefficients were determined using the method of laser ablation in conjunction with inductively coupled plasma-mass spektrometry (LA-ICP-MS)

Percolation diffusion into self-assembled mesoporous silica microfibres

© 2014 by the authors. Percolation diffusion into long (11.5 cm) self-assembled, ordered mesoporous microfibres is studied using optical transmission and laser ablation inductive coupled mass spectrometry (LA-ICP-MS). Optical transmission based diffusion studies reveal rapid penetration ( 80 μm2·s−1) of Rhodamine B with very little percolation of larger molecules such as zinc tetraphenylporphyrin (ZnTPP) observed under similar loading conditions. The failure of ZnTPP to enter the microfibre was confirmed, in higher resolution, using LA-ICP-MS. In the latter case, LA-ICP-MS was used to determine the diffusion of zinc acetate dihydrate, D~3 × 10−4 nm2·s−1. The large differences between the molecules are accounted for by proposing ordered solvent and structure assisted accelerated diffusion of the Rhodamine B based on its hydrophilicity relative to the zinc compounds. The broader implications and applications for filtration, molecular sieves and a range of devices and uses are described

Laser ablation inductively coupled plasma mass spectrometry for direct analysis of the spatial distribution of trace elements in metallurgical-grade silicon

The spatial distribution and concentration of impurities in metallurgical-grade silicon (MG-Si) samples (97-99% w/w Si) were investigated by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The spatial resolution (120μm) and low limits of detection (mg kg−1) for quality assurance of such materials were studied in detail. The volume-dependent precision and accuracy of non-matrix-matched calibration for quantification of minor elements, using NIST SRM 610 (silicate standard), indicates that LA-ICP-MS is well suited to rapid process control of such materials. Quantitative results from LA-ICP-MS were compared with previously reported literature data obtained by use of ICP-OES and rf-GD-OES. In particular, the distribution of element impurities and their relationship to their different segregation coefficients in silicon is demonstrate

Elemental bio-imaging of trace elements in teeth using laser ablation-inductively coupled plasma-mass spectrometry

Objectives: In this study we present the application of a novel laboratory method that employs laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to construct two-dimensional maps of trace elements in teeth. Methods: Teeth were sectioned longitudinally, embedded in resin and polished to a smooth surface. Data were generated by laser ablating the entire sectioned tooth surface. Elemental images were constructed using custom-built software. Results: Quantified images of 66Zn, 88Sr, 111Cd and 208Pb, with a spatial resolution of 30 μm2, were generated from three teeth. Concentrations were determined by single-point calibration against NIST SRM 1486 (bone meal). Zn and Sr concentrations were determined in the μg g-1 range and Cd and Pb in the ng g -1 range. Concentrations of Pb, Zn and Cd were higher in dentine particularly in regions adjacent the pulp. Conclusions: Elemental bio-imaging employing LA-ICP-MS is a novel method for constructing μm-scale maps of trace elements in teeth. This simple imaging method displays the heterogeneity of trace elements throughout the tooth structure that correspond to specific structural and developmental features of teeth. As a preliminary study, this work demonstrates the capabilities of LA-ICP-MS imaging in dental research. © 2011 Elsevier Ltd. All rights reserved

Solution and laser ablation inductively coupled plasma-mass spectrometry measurements of Br, I, Pb, Mn, Cd, Zn, and B in the organic skeleton of soft corals and black corals

Proxy records can be derived from soft corals and black corals using minor and trace element measurements of the organic skeleton of these corals. Here, concentrations of Br, I, Pb, Mn, Cd, Zn, and B in the organic skeleton were determined using solution inductively coupled plasma-mass spectrometry (ICP-MS) in one black coral from 5 m depth and two soft corals from 85 and 105 m depth collected from a reef offshore of Palau in the western tropical Pacific. Solution ICP-MS results indicate that concentrations of some elements vary as expected with depth (Cd and Mn) while others are taxa specific (I) or colony specific (Br, Pb, Zn, and B). The intensities of the same elements normalized to ^13C were also measured at high resolution using laser ablation (LA) ICP-MS along radial transects covering the lifespan of the colonies. The results here indicate that high-resolution LA ICP-MS elemental records in black corals could be more fully developed for paleoceanographic reconstructions. In contrast, results of the laser transects from the two soft corals were not reproducible for any of the elements, and no discernible patterns were detected that could be developed into reliable proxy records using the current LA ICP-MS method

Validation of an Analytical Method for the Identification of SmartWater CSI Forensic Marking Technology

SmartWater is a chemical taggant used as a crime deterrent. The chemical taggant is a colorless liquid that fluoresces yellow under ultra-violet (UV) light and contains distinctive, identifiable and traceable elemental composition. For instance, upon a break and entry scenario, the burglar is sprayed with a solution that has an elemental signature custom-made to a specific location. The residues of this taggant persist on skin and other objects and can be easily recovered for further analysis. The product has been effectively used in Europe as a crime deterrent and has been recently introduced in South Florida. In 2014, Fourt Lauderdale Police Department reported the use of SmartWater products with a reduction in burglaries of 14% [1]. The International Forensic Research Institute (IFRI) at FIU validated the scientific foundation of the methods of recovery and analysis of these chemical tagging systems using LA-ICP-MS. Analytical figures of merit of the method such as precision, accuracy, limits of detection, linearity and selectivity are reported in this study. Moreover, blind samples were analyzed by LA-ICP-MS to compare the chemical signatures to the company’s database and evaluate error rates and the accuracy of the method. This study demonstrated that LA-ICP-MS could be used to effectively detect these traceable taggants to assist law enforcement agencies in the United States with cases involving transfer of these forensic coding systems

Femtosecond laser ablation-ICP-mass spectrometry analysis of a heavy metallic matrix : determination of platinum group metals and gold in lead fire-assay buttons as a case study

Owing to the shorter time interval during which energy is delivered to the sample material, femtosecond (fs) laser ablation is preferable over nanosecond laser ablation for metallic samples. In this project, the influence of various laser parameters-beam diameter, repetition rate and laser fluence-on the ablation of Pb as a heavy metallic matrix using an infrared (lambda = 795 nm) fs-LA system (150 fs pulse duration) was studied. The merits of Ar and He as carrier gases were compared and as He did not provide a substantial improvement in the limits of detection, while deposition of sample material on the window of the ablation chamber was more pronounced, Ar was selected for all further measurements. The effect on the ICP caused by the introduction of various amounts of sample aerosol was studied by monitoring the signal intensity for Ar-38(+). It was shown that maximizing the amount of sample ablated and thus, the amount of sample aerosol introduced into the ICP, did not result in maximum sensitivity, which was rather obtained under 'compromise' conditions. Subsequently, femtosecond LA-quadrupole-based ICP-mass spectrometry (ICP-MS) was used for the determination of traces of the platinum group metals (PGMs) Rh, Pd, Ru, Ir and Pt and of Au in Pb buttons obtained by fire assay of platiniferous ore reference materials. The signal of Pb-204(+) was used as an internal reference, correcting for variations in the laser ablation and transport efficiencies and in the instrument's sensitivity. The spectral interferences established for some of the target nuclides due to the occurrence of Pb2+ ions were successfully overcome by pressurizing the reaction cell with NH3. Quantification versus a calibration curve constructed on the basis of the results obtained for matrix-matched standards (>99% Pb) provided excellent accuracy, superior to those obtained using nanosecond LA-ICP-MS. Also the limits of detection were improved by a factor ranging between 3 and 10 and are <0.010 mu g g(-1) for the most important PGMs (Rh, Pd, Pt) and Au. Several measures, such as the use of a large ablation cell and housing up to 10 Pb buttons, were taken to increase the sample throughput. In the same context, day-to-day reproducibility of the calibration curve was also examined. When recording a 'fresh' calibration curve every day, the average bias between the experimental results and the corresponding reference values was established to be <2.5% for every target element. When using one calibration curve during three consecutive days, the bias still remains <10%, while the sample throughput is increased and analysis of several tens of buttons per day is feasible (10-15 min total analysis time per sample)