Inductively Coupled Plasma Mass Spectrometry Measurements Research Articles

Investigating Cobalt Degradation in Acidic Environments for Oxygen and Hydrogen Electrocatalysis with Time-Resolved Mass Spectrometry Techniques

Cobalt is an important additive within commercially available energy devices including hydrogen fuel cell vehicles, lithium-ion batteries for electric vehicles and portable devices, and electrolyzers for water splitting. Regarding devices that include a proton exchange membrane (PEM), such as proton exchange membrane fuel cells (PEMFCs) and proton exchange membrane water electrolyzers (PEMWEs), cobalt-based materials are commonly used to perform the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), respectively. However, given the acidic environment induced by the PEM (pH = 1), cobalt is thermodynamically unstable at ORR and HER relevant potentials, which results in cobalt dissolution and consequently decreases in device performance and lifetime. Minimizing electrode degradation of cobalt-based materials in acidic environments therefore requires a holistic understanding of cobalt’s degradation mechanisms, as it would be necessary to simultaneously monitor electrochemical output (current/voltage), cobalt dissolution, and product formation, which is not possible with one technique alone. To gain such an understanding, in this presentation I will discuss our work on developing comparable time-resolved techniques such as on-line inductively coupled plasma mass spectrometry (ICP-MS) and electrochemical mass spectrometry (EC-MS) to investigate the relationship between applied potential, time, cobalt dissolution, and product formation.With usage of EC-MS, it was observed that cobalt is active for HER in 0.1 M HClO4. and undergoes little to no cobalt dissolution (< 1 ng s-1) at potentials where cobalt is evolving H2 per ICP-MS measurements. This suggests that cobalt stability in acid strongly coincides with hydrogen evolution. In addition, when comparing cobalt’s material stability from the on-line ICP-MS experiments with its thermodynamic stability from its Pourbaix diagram, there is little to no cobalt dissolution at potentials outside its thermodynamic stability window. This is unexpected, as cobalt is projected to be thermodynamically stable only at potentials less than -0.277 VRHE (Co2+/Co = -0.277 VRHE for a dissolved total metal ion concentration of 1 M at pH = 1), whereas our data shows that cobalt dissolution is suppressed until -0.05 VRHE. Through combining findings from both EC-MS and ICP-MS, we have postulated a stability mechanism related to surface hydrogen coverage on cobalt that can be used to explain why cobalt is stable during HER and at potentials it is thermodynamically expected to be unstable.In addition to cobalt being HER active, we also uncovered its activity for ORR in O2 saturated 0.1 M HClO4. Cobalt dissolution under O2 versus N2 saturated 0.1 M HClO4 was then compared, and it was observed that in the presence of O2, cobalt dissolution occurs faster (~3x more dissolution), likely due to O2 induced chemical dissolution. However, after 3 cycles, the observed cobalt dissolution rates under both gas types are equivalent (~225 ng s-1), indicating an important relationship between time, potential, and electrochemical environment. Altogether, this work showcases how time-resolved techniques such as ICP-MS and EC-MS can be connected to unravel stability mechanisms of materials and motivative future studies to apply a holistic approach when evaluating material stability.

New methodological approach for deep penetrating geochemistry and environmental studies, Part 2: field determination of Co(II)/Ni(II) and Pb(II)/Zn(II) of on-site soil extractions by electrochemical stripping techniques

In the framework of deep penetrating geochemistry for mineral exploration, we report a field electroanalytical method using disposable screen-printed working electrodes able to quantify metal pathfinders in partial extracts of soil samples at the nanomolar level on-site. Four metal pathfinders (Co, Ni, Pb and Zn) were chosen due to their geological interest and suitability of electrochemical detection. Square-wave anodic stripping voltammetry (SW-ASV) was developed for the simultaneous detection of Pb(II) and Zn(II) providing limits of detection (LOD) of 1.2 and 5.3 nM, respectively. A linear-scan cathodic stripping voltammetry (LS-CSV) methodology was developed for the joint detection of Co(II) and Ni(II) yielding LOD of 1.8 and 3.5 nM, respectively. Method validation was carried out on 14 upper B-horizon soil samples during a field survey. Two wet extraction procedures were applied for soil samples – a strong extraction using nitric acid (HNO 3 ) and a weak extraction using calcium chloride (CaCl 2 ). Excellent agreement between electroanalytical methods and inductively coupled plasma mass spectrometry (ICP-MS) was found for Pb(II), while a small underestimation was observed for Zn(II). For Co(II) and Ni(II) the LS-CSV measurements in the HNO 3 extractions were impossible due to the change from low pH to pH to 7.15 which induces precipitation of iron and aluminium. For the CaCl 2 extractions, the Co(II)/Ni(II) results obtained by LS-CSV were in excellent agreement with ICP-MS measurements.

Juvenile downstream migration patterns of an anadromous fish, allis shad (Alosa alosa), before and after the population collapse in the Gironde system, France.

Diadromous fish have exhibited a dramatic decline since the end of the 20th century. The allis shad (Alosa alosa) population in the Gironde-Garonne-Dordogne (GGD) system, once considered as a reference in Europe, remains low despite a fishing ban in 2008. One hypothesis to explain this decline is that the downstream migration and growth dynamics of young stages have changed due to environmental modifications in the rivers and estuary. We retrospectively analysed juvenile growth and migration patterns using otoliths from adults caught in the GGD system 30 years apart during their spawning migration, in 1987 and 2016. We coupled otolith daily growth increments and laser ablation inductively-coupled plasma mass spectrometry measurements of Sr:Ca, Ba:Ca, and Mn:Ca ratios along the longest growth axis from hatching to an age of 100 days (i.e., during the juvenile stage). A back-calculation allowed us to estimate the size of juveniles at the entrance into the brackish estuary. Based on the geochemistry data, we distinguished four different zones that juveniles encountered during their downstream migration: freshwater, fluvial estuary, brackish estuary, and lower estuary. We identified three migration patterns during the first 100 days of their life: (a) Individuals that reached the lower estuary zone, (b) individuals that reached the brackish estuary zone, and (c) individuals that reached the fluvial estuary zone. On average, juveniles from the 1987 subsample stayed slightly longer in freshwaterthan juveniles from the 2016 subsample. In addition, juveniles from the 2016 subsample entered the brackish estuary at a smaller size. This result suggests that juveniles from the 2016 subsample might have encountered more difficult conditions during their downstream migration, which we attribute to a longer exposure to the turbid maximum zone. This assumption is supported by the microchemical analyses of the otoliths, which suggests based on wider Mn:Ca peaks that juveniles in 2010s experienced a longer period of physiological stress during their downstream migration than juveniles in 1980s. Finally, juveniles from the 2016 subsample took longer than 100 days to exit the lower estuary than we would have expected from previous studies. Adding a new marker (i.e., Ba:Ca) helped us refine the interpretation of the downstream migration for each individual.

(General Student Poster Award Winner - 1st Place) Six Practices to Improve Alkaline Electrolyte Preparation

Alkaline electrolytes represent a critical component of electrochemical energy devices, including alkaline electrolyzers, fuel cells, supercapacitors, and alkaline batteries. In addition, these electrolytes define essential properties of electrocatalytic reactions, such as the oxygen evolution reaction (OER), the hydrogen evolution reaction (HER), and the oxygen reduction reaction (ORR). However, alkaline electrolyte concentrations and compositions are often considered trivial, resulting in misinterpretation of different phenomena and overestimating critical performance metrics. Thus, in an expanding field full of interdisciplinary research groups, there is an urgent need for standardized protocols designed to improve and evaluate the quality of alkaline electrolytes so that electrochemical energy systems can be objectively examined and compared.In this work, we propose a protocol composed of six steps to prepare, characterize and validate the quality of common alkaline electrolytes. By adapting well-established methods in the literature and validating additional features experimentally, we standardize six general practices: (1) proper alkaline electrolyte handling and preparation, (2) removal of Fe impurities, (3) alkali molarity standardization via pH titrations, (4) electrolyte composition analysis via inductively-coupled plasma mass spectrometry (ICP-MS), (5) statistical quality control assessment and (6) electrolyte validation through electrochemical aging of Ni electrodes in alkaline media. The effects of Fe incorporation for different alkaline electrolytes were examined using Ni and NiFe foam electrodes. Furthermore, ICP-MS measurements were complemented with prolonged cyclic voltammetry tests to confirm the effectiveness of the Fe purification procedure. We believe this work illustrates the importance of standardizing protocols and reporting reliable quality metrics to improve consistency and accuracy in electrochemistry. Furthermore, adopting the practices presented in this work would greatly benefit the evaluation and comparison of electrochemical energy materials and devices operating with alkaline electrolytes. Figure 1

Measuring Th and U contaminants in PPO to 10−14 g/g level via acid extraction

A reliable and precise method for determining the thorium (Th) and uranium (U) contaminants in 2,5-diphenyloxazole (PPO) to 10 ppq level was developed for Jiangmen Underground Neutrino Observatory (JUNO). The Th and U contaminants were separated from PPO by acid extraction and measured by inductively coupled plasma mass spectrometry (ICP-MS). The experimental conditions were optimized to improve extraction efficiencies and eliminate the interferences during the ICP-MS measurements. The 229Th and 233U isotopes were used as tracer, and nearly 100% recovery efficiencies of 229Th and 233U were obtained in both the spiked PPO samples and blanks. The method detection limits with 99% confidence level for 232Th and 238U in PPO were 3.3×10−14 g/g and 4.0×10−14 g/g, respectively. The measurements were consistent with the Th and U results obtained from a vaporization method. The method developed in this work can be extended to other fluors with minor adjustments.

Study Design on the Presence of Metals in Moisturisers, and Compliance with Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of the European Union, on Cosmetic Products

Metals are present in cosmetics due to deliberate addition by the manufacturers, contamination of raw materials, and/or contamination during their manufacture or storage. The objective of this work was to explore the metal content in the most-consumed moisturising creams on the Spanish market, to verify their degree of compliance with Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of the European Union, regarding the presence of metals in cosmetics. The moisturisers were digested (microwave-assisted acid digestion) and analysed by inductively coupled plasma-mass spectrometry (ICP-MS), for metal assessment. The ICP-MS measurements were successfully validated (RSDs lower than 5% and analytical recoveries within the 91–110% range). Metals banned in cosmetics were found at very low concentrations in some of the moisturisers, as inevitable traces of pollutants. This was the case with beryllium (found in only two samples, at concentrations lower than 0.10 µg g−1), cadmium (found at 0.075 µg g−1 in one sample), mercury (found in four samples at concentrations within the 0.10–0.18 µg g−1 range), and lead (also found in four samples at concentrations from 0.03 to 0.44 µg g−1). Furthermore, nickel (0.16–0.56 µg g−1, six samples), chromium (0.09–0.30 µg g−1, three samples), and cobalt (lower than 0.13 µg g−1, two samples) were also found in the analysed creams.

Uncertainty derived from elemental analysis and its effect on the separation of radioactive waste into low-level radioactive waste and waste for clearance

Radioactive cobalt (Co), cesium (Cs), and europium (Eu), produced by neutron-capture reactions of the corresponding trace elements, are the main radioactive components of concrete waste in the decommissioning of aged nuclear power stations. The uncertainty regarding the activity of individual nuclide produced by activation is a main factor for efficient separation of radioactive wastes. Major and trace elements in the geostandard reference JG-3, aggregates collected from quarries, and cements, were analyzed by four different methods to evaluate experimentally the uncertainty. Neutronactivation analysis, a non-destructive technique, and analysis by using instruments such as an inductively coupled plasma mass spectrometry (ICP-MS) following sample digestion by alkali fusion have uncertainties of 30% for the content of major and trace elements. ICP-MS measurements following digestion by HF or K2S2O3 showed a poorer precision, especially for the trace elements. The Monte Carlo simulation using PHITS code was performed to estimate the depth profiles and uncertainty for the radionuclides produced by activation in the concrete including the uncertainty derived from the elemental analyses and local variability. On the basis of the uncertainty, we evaluated the boundary depth between low-level radioactive waste and waste for clearance in a bioshield for the prudent separation.

Silicon-Based Ag Dendritic Nanoforests for Light-Assisted Bacterial Inhibition.

Silver dendritic nanoforests (Ag-DNFs) on silicon (Ag-DNFs/Si) were synthesized through the fluoride-assisted Galvanic replacement reaction (FAGRR) method. The synthesized Ag-DNFs/Si were characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), reflection absorbance spectrometry, surface-enhanced Raman scattering spectrometry, and X-ray diffractometry. The Ag+ concentration in ICP-MS measurements indicated 1.033 mg/cm2 of deposited Ag synthesized for 200 min on Si substrate. The optical absorbance spectra indicated the induced surface plasmon resonance of Ag DNFs increased with the thickness of the Ag DNFs layer. Surface-enhanced Raman scattering measurement and a light-to-heat energy conversion test presented the superior plasmonic response of Ag-DNFs/Si for advanced applications. The Ag-DNFs/Si substrate exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus. The large surface area of the dense crystal Ag DNFs layer resulted in high antibacterial efficiency. The plasmonic response in the metal–crystal Ag DNFs under external light illumination can supply energy to enhance bacterial inhibition. High-efficiency plasmonic heating by the dense Ag DNFs can lead to localized bacterial inhibition. Thus, the Ag-DNFs/Si substrate has excellent potential for antibacterial applications.

Isotopic and Elemental Analysis of Apple and Orange Juice by Isotope Ratio Mass Spectrometry (IRMS) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS)

Twenty-five samples, consisting of 15 commercial juices and 10 directly pressed orange and apple juice samples were analyzed by isotope ratio mass spectrometry (IRMS) and inductively coupled plasma – mass spectrometry (ICP-MS). The isotopic results showed that most of the commercial fruit juices were made from concentrate by re-dilution with water and five of investigated juices contain C4 sugars from corn or cane sugar. The differences between the concentrations of macronutrients in the juice samples indicate that the mineral fertilization, soil characteristics, and the addition of preservatives or adulterants, influence the quality and nutritional values of the product. In order to extract the most meaningful information and to highlight the influence upon the analytical results obtained from the IRMS and ICP-MS measurements, linear discriminant analysis (LDA) was used. δ13C, Ni, Cr, Ca, Sr, Fe, K, Mg and Na were shown to be the best markers for the differentiation of orange from apple juice. Also, the best predictors for the discrimination of commercial from directly pressed juice were δ18O, K and Na.

Development and Validation of a Sector-Field Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) Method for Analyzing the Diagenesis-Designating Metals in Marine Sediments

The inductively coupled plasma – mass spectrometry (ICP-MS) technique was applied for the quantification of specific metals in marine sediments following a four-step microwave-assisted digestion protocol. The effects of microwave heating and digesting medium on metal recovery were investigated using lake and river sediment reference materials to minimize the deviations from certified values. Increasing the temperature and time variables improves the accuracy of the ICP-MS measurements so that an optimized acid-digestion protocol enables the determination of heavy metals in sediments with relative errors better than 10%. The developed method was applied to measure longitudinal metal distribution in sediments collected from the continental shelf of the East Siberian Sea in the range from 50 to 600 km. Minima in the content of redox sensitive elements such as Mn, Mo, V, U, and Sb at distances from 200 to 300 m to the coast are most likely related to diagenetic processes such as sulfide reduction in the upper part of the sediment. In addition, the quality of sediments under consideration was assessed in terms of the average and maximum concentrations of heavy metals that may contaminate the bottom seawater. The developed method can be recommended as a standard tool for accurate and precise sediment analysis with important geochemical and environmental implications.

Liquid scintillation counter calibration approach for 90Sr detection and testing performance of TK100 resin

90Sr detection efficiency determination was applied for liquid scintillation counting (LSC) by computing a model for the relation between detection efficiency and the time passed since radiochemical separation. This allowed more flexibility in analysis times after separation as the model accounts for 90Y in-growth. Establishment of secular equilibrium was therefore not required for LSC measurements. In addition, this approach increases counting efficiency compared to classical ones as both 90Sr and 90Y spectrums are used. This in turn has a positive impact on minimum detectable activity. The method was validated using proficiency test samples for both Čerenkov radiation measurement and scintillation cocktail measurement. Commonly used extraction material Sr-resin was compared to alternative, TK100 resin. Inductively-coupled plasma mass spectrometry measurements for recovery determination showed limitations for TK100 usage due to incomplete Sr retention on the resin. Limitations were further confirmed by LSC activity measurements.

Trace element soil contamination at a former shooting range in Athens, Greece

This study was focused on the determination of lead, zinc and nickel in a former shooting range in Athens, Greece. In order to propose a hybrid methodology, two analytical techniques were complimented, namely inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence (XRF). Analysis by ICP-MS was carried out over a minimum of locations following international sampling guidelines whereas analysis by XRF was carried out using a portable device and over a denser sampling design. After analyzing certified reference materials, the reliability of both techniques was Pb>Zn>Ni. Linear correlation analysis between techniques suggests that at least some degree of homogenization must be carried out in the field to achieve reliable results with XRF. Characterization maps were built using data from both techniques. A comparison of areas of concern led to the conclusion that the proposed hybrid methodology allows a highly efficient delineation of the contamination and that additional improvement in the characterization can be reached by correcting the XRF data by calibration against ICP-MS measurements.

Comparison between inductively coupled plasma and X-ray fluorescence performance for Pb analysis in environmental soil samples

Comparison of two conventional analytical techniques such as X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) for measuring Pb concentrations in soil samples was achieved using field and laboratory work. Seventy-three samples were collected from urban areas surrounding the large lead smelter at South Australia, as an indicator of the environment impact of smelter activity. Soil Pb concentrations were determined using hand-held XRF analyser under laboratory conditions. ICP-MS analysis on digested soils (using a microwave-assisted nitric acid digestion-extraction) was applied to validate p-XRF data. The analysis showed that Pb concentrations determined by XRF correlated with high linearity with Pb concentrations determined by ICP-MS measurements (R2 = 0.89). Statistical test (t test) was applied to the data of both methods applied without any significant difference between the two techniques. These results indicated that ICP-MS corroborated XRF for Pb soil measurements and suggests that XRF was a reliable and quick alternative to traditional analytical methods in studies of environmental health risk assessment, allowing for much larger sampling regimes in relatively shorter times and could be applied in the field.

Glutathione Modified Gold Nanoparticles for Sensitive Colorimetric Detection of Pb2+ Ions in Rainwater Polluted by Leaking Perovskite Solar Cells.

In the past few years, the advent of lead halide perovskite solar cells (PSCs) has revolutionized the prospects of the third- generation photovoltaics and the reported power conversion efficiency (PCE) has been updated to 22%. Nevertheless, two main challenges, including the poisonous content of Pb and the vexing instability toward water, still lie between the lab-based PSCs technology and large scale commercialization. With this background, we first evaluated Pb2+ concentration from the rainwater samples polluted by three types of markets promising PSCs with inductively coupled plasma mass spectrometry measurements (ICP-MS) as a case study. The influence of possible conditions (pH value and exposure time) on the contents of Pb2+ from the three PSCs was systematically compared and discussed. Furthermore, an optimized glutathione functionalized gold nanoparticles (GSH-AuNPs) colorimetric sensing assay was used to determine Pb2+ leaking from PSCs for the first time. The Pb2+-induced aggregation of sensing assay could be monitored via both naked eye and UV-vis spectroscopy with a detection limit of 15 and 13 nM, which are all lower than the maximum level in drinking water permitted by WHO. The quantitative detection results were compared and in good agreement with that of ICP-MS. The results indicate that the content of Pb2+ from three PSCs are in the same order of magnitude under various conditions. By the use of the prepared GSH-AuNPs self-assembled sensing assay, the fast and on-site detection of Pb2+ from PSCs can be realized.

Improved methodology for the microwave digestion of carbonate-rich environmental samples

ABSTRACTMicrowave-assisted digestion permits a rapid and total dissolution of sediments and various other sample types, allowing easier and more accurate multi-element determinations. In this study, we present an optimised microwave digestion method for the complete digestion of 200 mg of carbonate-rich sediments. The optimised method prevents the formation of precipitates and assures a complete dissolution of the material. The optimised method involves treatment with concentrated hydrochloric acid (HCl) prior to microwave digestion, which prevents the formation of an insoluble calcium fluoride precipitate associated with the use of hydrofluoric acid (HF). Three different certified reference samples along with a pure calcium carbonate standard and a carbonate-rich in-house marine sediment sample were considered. Sediments were found to only be partially digested if insufficient HF was present, while a noticeable fluoride-based precipitate was found if excess HF was present. Twenty elements were analysed using sector field inductively coupled plasma mass spectrometry (ICP-MS) (Al, Ag, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Na, Ni, Sr, Th, Ti, U, V and Zn). A total sample digestion with average elemental recoveries above 90% was obtained by reacting carbonate-rich samples with HCl on a hotplate at 150°C for 2 h (time for the total release of generated CO2), prior to any microwave digestion step. This extra step prevented the accumulation of gas in the sealed vessels during digestion, which would otherwise influence the carbonate chemical equilibria and make insoluble calcium available for precipitation. After this initial treatment, the improved digestion method consisted of microwave attack employing a mix of concentrated HCl, nitric acid (HNO3) and HF (4 mL/10 mL/2 mL), followed by evaporation on a hotplate. The limits of detection (LOD) obtained using the optimised microwave protocol and ICP-MS measurements were below 0.1 µg/kg for the trace elements and below 0.2 mg/kg for major elements.

Enhanced detection of DNA sequences using end-point PCR amplification and online gel electrophoresis (GE)-ICP-MS: determination of gene copy number variations.

The design and evaluation of analytical methods that permit quantitative analysis of specific DNA sequences is exponentially increasing. For this purpose, highly sensitive methodologies usually based on labeling protocols with fluorescent dyes or nanoparticles are often explored. Here, the possibility of label-free signal amplification using end-point polymerase chain reaction (PCR) are exploited using on-column agarose gel electrophoresis as separation and inductively coupled plasma-mass spectrometry (ICP-MS) for the detection of phosphorus in amplified DNA sequences. The calibration of the separation system with a DNA ladder permits direct estimation of the size of the amplified gene fragment after PCR. With this knowledge, and considering the compound-independent quantification capabilities exhibited by ICP-MS for phosphorus (it is only dependent on the number of P atoms per molecule), the correlation of the P-peak area of the amplified gene fragment, with respect to the gene copy numbers (in the starting DNA), is then established. Such a relationship would permit the determination of copy number variations (CNVs) in genomic DNA using ICP-MS measurements. The method detection limit, in terms of the required amount of starting DNA, is ∼6 ng (or 1000 cells if 100% extraction efficiency is expected). The suitability of the proposed label-free amplification strategy is applied to CNVs monitoring in cells exposed to a chemical agent capable of deletion induction, such as cisplatin.

Combining HPLC–DAD and ICP-MS data for improved analysis of complex samples: Classification of the root samples from Cortex moutan

A combined data matrix consisting of high performance liquid chromatography–diode array detector (HPLC–DAD) and inductively coupled plasma-mass spectrometry (ICP-MS) measurements of samples from the plant roots of the Cortex moutan (CM), produced much better classification and prediction results in comparison with those obtained from either of the individual data sets. The HPLC peaks (organic components) of the CM samples, and the ICP-MS measurements (trace metal elements) were investigated with the use of principal component analysis (PCA) and the linear discriminant analysis (LDA) methods of data analysis; essentially, qualitative results suggested that discrimination of the CM samples from three different provinces was possible with the combined matrix producing best results. Another three methods, K-nearest neighbor (KNN), back-propagation artificial neural network (BP-ANN) and least squares support vector machines (LS-SVM) were applied for the classification and prediction of the samples. Again, the combined data matrix analyzed by the KNN method produced best results (100% correct; prediction set data). Additionally, multiple linear regression (MLR) was utilized to explore any relationship between the organic constituents and the metal elements of the CM samples; the extracted linear regression equations showed that the essential metals as well as some metallic pollutants were related to the organic compounds on the basis of their concentrations.

Simple, common but functional: biocompatible and luminescent rare-earth doped magnesium and calcium hydroxides from miniemulsion.

Nanostructured (d∼ 20-35 nm) and highly luminescent Ca(OH)2:Ln and Mg(OH)2:Ln (Ln = EuIII, SmIII, TbIII, Mg(Ca)/Ln = 20 : 1 atomic) nanostructures were obtained in inverse (water in oil - w/o) miniemulsion (ME), by exploiting the nanosized compartments of the droplets to spatially confine the hydroxide precipitation in basic environment (NaOH). The functional nanostructures were prepared using different surfactants (Span80 (span) and a mixture of Igepal co-630 and Brij 52 (mix)) to optimise ME stability and hydroxide biocompatibility as well as tune the droplet sizes. X-Ray diffraction (XRD) analyses testify the achievement of a pure brucite-Mg(OH)2-phase and pure portlandite-Ca(OH)2-phase with a high degree of crystallinity. Besides structural characterisations, the products were thoroughly characterised by means of several and complementary techniques (dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), micro-Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS) and Fourier transform infrared spectroscopy (FT-IR)) to assess their chemico-physical properties as well as their morphological and microstructural features. The stoichiometry of the doped systems was confirmed using ICP-MS measurements. Finally, the cytotoxicity of the nanoparticles was assessed by in vitro tests using ES2 cells in order to provide preliminary data on the biocompatibility of this kind of nanoparticles. The luminescence of the Eu-doped and Tb-doped materials is clearly visible to the naked eye in the red and green regions, respectively, corroborating their employment as materials for imaging in the optical window of interest.

Use of chromatographic pre-concentration for routine uranium bioassay analysis by ICP-MS

Routine monitoring of urine is an effective way to detect occupational intake of radioactive material. Historically, determinations of uranium isotopic ratios have been performed by radiochemical separation followed by alpha spectrometry. With recent advancements in technology, inductively coupled plasma-mass spectrometry (ICP-MS) has become widely available for the determination of trace metals as well as radioactive nuclides with long half-lives, such as 238U in urine. Furthermore, ICP-MS measurements of 238U do not require radiochemical separation since the number of atoms in the sample is determined instead of the number of alpha particles emitted. However, this method does not provide good sensitivity for the determination of 235U due to its shorter half-life. An improved procedure using pre-concentration of uranium and determination by ICP-MS decreases the detection limit by a factor of ten or greater with only slight increase in total analysis time. The method also has the capability of accurately determining the isotopic ratio of the sample, which is very important in cases where enriched or depleted uranium is involved.

Solid Phase Extraction Using a Sulfoxide Adsorbent for Preconcentration and Separation of Hg(II) in Natural Water Followed by ICP-MS Measurements

A separation and preconcentration method based on solid-phase extraction using sulfoxide adsorbent was developed for the determination of Hg(II) in natural water samples by inductively coupled plasma mass spectrometry (ICP-MS). The sulfoxide adsorbent was packed into a commercially available syringe-driven column (with a bed volume of 1.0 mL), which permitted off-line sample loading and on-line elution/measurement. The optimized operating conditions were as follows: sample condition for Hg(II) adsorption, 0.5% HCl; sample-loading flow rate, 10 mL min(-1); eluent for recovering Hg(II), 1% cysteine water solution. A test using multi-element mixed solution showed that most trace elements in natural water, except for Bi, could be completely separated from Hg(II). The recoveries of Hg(II) were 99.0 ± 3.2 and 100.7 ± 4.3%, respectively, when 0.64 and 0.16 ng mL(-1) of Hg(II) were added into the test sample. The detection limit of Hg(II) using a quadrupole ICP-MS after 10-fold preconcentration was 1.5 pg mL(-1). The blank value was 2.8 ± 0.5 pg mL(-1).