Coupled Plasma Quadrupole Mass Spectrometry Research Articles

Improved lifetime of a pulsed electric field (PEF) system-using laser induced surface oxidation

In this research, we explore the possibility and effectiveness of using laser-induced surface oxidation methods to enhance the durability and effectiveness of PEF (Pulsed Electric Field) systems. Despite advantages over thermal pasteurisation, PEF faces challenges like electrode corrosion and biofouling, hindering its adoption. This research introduces laser-induced oxidation to mitigate metal ion release during PEF, directly targeting electrode alteration. Our examination adopts a comprehensive method, integrating Design of Experiments (DoE) parameter sets for PEF trials, morphological analysis, evaluation of metal ion release via Inductively Coupled Plasma Quadrupole Mass Spectrometry (ICP-QMS), waveform capture utilizing a Data Acquisition (DAQ) system, electrochemical assessment via impedance spectroscopy, and examination of oxide layer composition employing X-ray photoelectron spectroscopy. Pulse waveform characteristics shows the intricate relationship between PEF processing parameters with metal ion release, alongside XPS analysis providing insights into surface chemistry. Optimized results show a three-fold reduction in metal ion release post-PEF, with laser-treated samples outperforming untreated stainless steel due to selective surface chemistry alteration, notably an increased Cr/Fe ratio, reducing harmful elements. This study highlights laser-induced oxidation as a practical solution for enhancing PEF electrode performance and reducing metal ion release, addressing key challenges in PEF technology. It advances sustainable food processing, promising extended PEF system lifespan while maintaining efficiency and product quality.

Single Cell Phenotypic Analysis for Cancer Stem Cell Identification by Dual-Isotope ICP-QMS.

Single cell phenotypic analysis is significant for clinical diagnosis, treatment, and prognosis of cancer. Accurate differentiation of cancer stem cell (CSC) subpopulations from a large number of cancer cells may become a cancer surveillance tool and provide important implications for the development of new CSC-targeted therapy strategies. Herein, we report a new approach based on dual-isotope inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) for single cell phenotypic analysis. High-throughput single cell sampling was achieved by a spiral channel microfluidic chip for cell focusing and alignment, and single cell analysis was performed with time-resolved ICP-QMS by identifying the highly specific probes. This enables the monitoring of two surface protein markers (EpCAM and MUC1) of three cell types, i.e., HeLa, MCF-7, and HepG2, at single cell level. The analysis of breast cancer stem cells further confirmed its capability in distinguishing rare cell phenotypes. The present study provides promising possibilities for adopting ICP-QMS in biomedical investigations in terms of cell typing, stemness identification of tumor cells, and cell heterogeneity analysis.

Effect of Exposure Concentration and Growth Conditions on the Association of Cerium Oxide Nanoparticles with Green Algae.

The increasing release of engineered nanoparticles (NPs) into aquatic ecosystems makes it crucial to understand the interactions of NPs with aquatic organisms, such as algae. In this study, the association of CeO2 NPs with unicellular algae (Raphidocelis subcapitata) and changes to the cellular elemental profile were investigated using three exposure concentrations (1, 50, and 1000 µg CeO2/L) at two different algal growth conditions-exponential and inhibited growth (1% glutaraldehyde). After a 24 h-exposure, algal suspensions were settled by gravity and CeO2-NP/algae association was analyzed by single-cell inductively coupled plasma quadrupole mass spectrometry (sc-ICP-QMS) and ICP time-of-flight MS (sc-ICP-TOFMS). Concurrent detection of the cellular fingerprint with cerium indicated NP association with algae (adsorption/uptake) and changes in the cellular elemental profiles. Less than 5% of cells were associated with NPs when exposed to 1 µg/L. For 50 µg/L exposures in growing and inhibited cell treatments, 4% and 16% of cells were associated with CeO2 NPs, respectively. ICP-TOFMS analysis made it possible to exclude cellular exudates associated with CeO2 NPs due to the cellular fingerprint. Growing and inhibited cells had different elemental profile changes following exposure to CeO2 NPs-e.g., growing cells had higher Mg and lower P contents independent of CeO2 concentration compared to inhibited cells.

High-Efficiency Miniaturized Ultrasonic Nebulization Sample Introduction System for Elemental Analysis of Microvolume Biological Samples by Inductively Coupled Plasma Quadrupole Mass Spectrometry

Sensitive and high-throughput analysis of trace elements in volume-limited biological samples is highly desirable for clinical research and health risk assessments. However, the conventional pneumatic nebulization (PN) sample introduction is usually inefficient and not well-suited for this requirement. Herein, a novel high-efficiency (nearly 100% sample introduction efficiency) and low-sample-consumption introduction device was developed and successfully coupled with inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). It consists of a micro-ultrasonic nebulization (MUN) component with an adjustable nebulization rate and a no-waste spray chamber designed based on fluid simulation. The proposed MUN-ICP-QMS could achieve sensitive analysis at a low sampling rate of 10 μL min-1 with an extremely low oxide ratio of 0.25% where the sensitivity is even higher comparing to PN (100 μL min-1). The characterization results indicate that the higher sensitivity of MUN is attributed to the smaller aerosol size, higher aerosol transmission efficiency, and improved ion extraction. In addition, it offers a fast washout (20 s) and reduced sample consumption (as low as 7 μL). The absolute LODs of the studied 26 elements by MUN-ICP-QMS are improved by 1-2 orders of magnitude compared with PN-ICP-QMS. The accuracy of the proposed method was validated by the analysis of human serum, urine, and food-related certified reference materials. Furthermore, preliminary results of serum samples from patients with mental illnesses demonstrated its potential in the field of metallomics.

Investigation of anthropogenic gadolinium in tap water of polish cities: Gdańsk, Kraków, Warszawa, and Wrocław

In urban areas where tap water is often produced by a purification of water supplied from a river bank filtration, a significant fraction of gadolinium (Gd) total pool is of an anthropogenic origin. It happens because Gd-based contrast agents used in Magnetic Resonance Imaging (MRI) are not removed during wastewater treatment and they are discharged to the environment and returned to the water cycle. Despite the growing number of MRI examinations worldwide, little is known about the anthropogenic Gd in Polish surface water as well as drinking water. The aim of this pilot study was to gain information about the occurrence of emergent pollution as Gd in potable water available for inhabitants of Polish municipal areas. Tap water samples from Gdańsk, Kraków, Wrocław and Warszawa were analyzed by an inductively coupled plasma quadrupole mass spectrometry after their preconcentration by a seaFAST-pico chromatographic system. In this study, the sum of REE was in the range registered in the drinking waters of European urban regions (usually below 100 ng/L). The highest values of the sum of REE total concentrations were observed in the tap water samples collected in Warszawa (37.7 ng/L) and Wrocław (35.9 ng/L and 32.9 ng/L), where water supplies originate from the Wisła River and Oława River, respectively. The highest total Gd concentration was observed in the tap water of Warszawa city where the anthropogenic Gd fraction represented about 90% of the total Gd. The lowest values of the sum REE were registered in tap waters of Gdańsk (sum of REE below 2.2 ng/L) with up to 17% of the anthropogenic Gd. Thus, our study showed the occurrence of the anthropogenic Gd in all analyzed tap waters.

New insight into the tectonic setting of fault-bounded Indian Gondwana coal basins from U–Pb detrital zircon provenance ages of the Bokaro and Jharia basins, central east India

AbstractA detrital zircon U–Pb laser ablation–inductively coupled plasma–quadrupole mass spectrometry (LA-ICP-QMS) provenance study was undertaken on samples selected from the Lower Gondwana successions preserved in the fault-bounded Bokaro and Jharia basins in India to investigate the provenance of the sediment and determine whether the strata were deposited in isolated syn-depositional graben basins or formed part of a wider regional depositional system. A total of 730 concordant U–Pb detrital zircon ages revealed six distinct age fractions: (i) a latest Neoproterozoic to earliest Cambrian age fraction (530 to 510 Ma), which tails down in some samples to older Neoproterozoic ages (650 to 630 Ma); (ii) a major age fraction with an age peak of earliest Neoproterozoic (950 Ma), accompanied in some samples by a twin Mesoproterozoic peak (1000 Ma); (iii) a middle Mesoproterozoic age fraction (1330 to 1300 Ma); (iv) a prominent earliest Mesoproterozoic zircon age fraction (1600 Ma); (v) a less well-defined late Palaeoproterozoic zircon age fraction (2100 to 1700 Ma, or 1600 Ma); and (vi) an Archaean zircon age fraction that typically comprises two zircon age fractions, namely zircons with early Neoarchaean ages (2800 to 2750 Ma) coupled with zircons with ages older than 3100 Ma. Comparison of these newly obtained age fractions with detrital zircon age data presented by Veevers & Saeed (2009) shows similarities with the Gondwana strata of the Mahanadi and Pranhita–Godavari basins, implying that strata preserved in the fault-bounded Gondwana basins in central east India formed part of a much wider regional depositional system and that they were not deposited in isolated half-graben or graben basins. Potential source regions to the Gondwana strata of the Bokaro and Jharia basins include the Eastern Ghats Mobile Belt and rock units in Antarctica.

Accurate determination of Pb and Bi contents and Pb isotopic composition in geological and cosmochemical samples by inductively coupled plasma quadrupole mass spectrometry

A method for accurately determining Pb and Bi contents in geochemical and cosmochemical solid samples using inductively coupled plasma quadrupole mass spectrometry (ICP–QMS) is described. Pb and Bi contents are determined using isotope dilution and calibration methods, respectively. For this purpose, an accurate determination scheme of Pb isotopic ratios is established using standard-sample bracketing and matrix-matching methods due to the significantly differences of Pb isotope ratios in commercial standard solution, geochemical and cosmochemical samples. Lead is chosen as the most appropriate internal standard element to reduce the matrix effect when determining Bi content. Our developed analytical procedure was applied to geological and cosmochemical reference samples to evaluate the accuracy of our data. The Pb isotopic composition data obtained from this study are in good agreement with the literature values obtained using multicollector inductively coupled plasma mass spectrometry and thermal ionization mass spectrometry, which ensures the accuracy of the Pb isotopic ratios obtained by our method. The Bi content data obtained from this study for a cosmochemical sample are in excellent agreement with neutron activation values in literature.

In Vitro Digestibility of Minerals and B Group Vitamins from Different Brewers' Spent Grains.

Brewers’ spent grain (BSG), the main by-product of the brewing industry, is a rich source of minerals and water-soluble vitamins such as thiamine, pyridoxine, niacin, and cobalamin. Bioaccessibility through in vitro digestion is an important step toward the complete absorption of minerals and B group vitamins in the gastrointestinal system. Inductively coupled plasma optical emission spectrometry (ICP-OES) together with inductively coupled plasma quadrupole mass spectrometry (ICP-MS) was used for the quantification of the macro- and micro-minerals. An ultra-high performance liquid chromatography (UHPLC) system coupled with a diode array detector (DAD) was used for B group vitamin identification. Four different industrial BSG samples were used in the present study, with different percentages of malted cereals such as barley, wheat, and degermed corn. Calcium’s bioaccessibility was higher in the BSG4 sample composed of 50% malted barley and 50% malted wheat (16.03%), while iron presented the highest bioaccessibility value in the BSG2 sample (30.03%) composed of 65% Pale Ale malt and 35% Vienna malt. On the other hand, vitamin B1 had the highest bioaccessibility value (72.45%) in the BSG3 sample, whilst B6 registered the lowest bioaccessibility value (16.47%) in the BSG2 sample. Therefore, measuring the bioaccessibilty of bioactive BSG compounds before their further use is crucial in assessing their bioavailability.

Discrimination and Quantification of Soil Nanoparticles by Dual-Analyte Single Particle ICP-QMS.

This study presents the new application of dual-analyte single particle inductively coupled plasma quadrupole mass spectrometry (spICP-QMS) to the discrimination and quantification of two typical soil nanoparticles (kaolinite and goethite nanoparticles, abbr. KNPs and GNPs) in three samples (SA, SB, and SC) with three detection events (Al unpaired event, Fe unpaired event, and paired event). SA was mainly composed of KNPs with a concentration of 28 443 ± 817 particle mL-1 and a mean particle size of 140.7 ± 0.2 nm. SB was mainly composed of GNPs with a concentration of 39 283 ± 702 particle mL-1 and a mean particle size of 141.8 ± 2.9. In SC, the concentrations of KNPs and GNPs were 22 4541 ± 1401 and 70 604 ± 1623 particle mL-1, respectively, and the mean particle sizes of KNPs and GNPs were 140.7 ± 0.2 and 60.2 ± 0.3 nm, respectively. The accuracy of dual-analyte spICP-QMS was determined by spiking experiments, comparing these results with the measurements of other techniques, analyzing the samples in different SA and SB proportions and in different SC concentrations. Our results demonstrated that the dual-analyte spICP-QMS is a promising approach to distinguishing different kinds of natural NPs in soils.

Chemical and Spectral Variations between Untreated and Heat-Treated Rubies from Mozambique and Madagascar

The chemical composition and spectra of untreated and heat-treated rubies from Mozambique and Madagascar were analyzed by an electron probe microscopy analysis, laser ablation inductively coupled plasma quadrupole mass spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-visible spectroscopy. Due to the different content of Fe and different inclusions, rubies from Madagascar belong to alkaline basalt deposit, while rubies from Mozambique belong to amphibole metamorphic rock. The ruby samples were heated to 900 °C to change their color. As Fe and Ti ions can be transferred into different valences and diffused into the interior of rubies, Cr ions in cracks or cleavages entered the crystal lattice during heat treatment and the content of Fe and Ti decreased, while the content of Cr increased in heat-treated rubies. After heating, blue-purple decreased and the red hue increased, while the blue color band disappeared and yellow appeared in the cracks of the samples because of the chemical changes. Compared with untreated rubies, the infrared absorption peaks of 2123 cm−1 and 1990 cm−1 related to inclusions disappeared, and the existence of 3236 cm−1 and 3186 cm−1 absorption peaks was a typical characteristic of heat-treated ruby, which was produced by changes in its inclusion. In addition, due to the weakened charge transfer of Fe2+ and Ti4+ and the increasing reaction of Fe2+ → Fe3+ along with the heat treatment, the UV-visible absorption peak at 400 nm shifted to purple.

The analysis of volcanic brines by freezing stage tandem LIBS-ICP-MS

Volcanic crater lakes pose unique hazards to the local population both during eruption and quiescence. The composition of crater lake fluids is therefore commonly monitored to aid hazard prediction and mitigation. Some of these fluids, such as at Kawah Ijen in Indonesia and Poas in Costa Rica, are hyper-acidic, concentrated brines (SO4–5 wt%, Cl - 2.5 wt%, Al - 5000 ppm). Analysis of such fluids requires extreme dilution due to the high total dissolved element load, which risks contamination and precipitate formation. To circumvent this undesired sample preparation and speed up the turn-around time on the analysis, we tested approaches which involved freezing the fluids to −30 °C and analysing them by simultaneous Laser Ablation-Inductively Coupled Plasma Quadrupole Mass Spectrometry (LA-ICP-QMS) and Laser-Induced Breakdown Spectroscopy (LIBS). LIBS is highly matrix sensitive, requiring matrix-matched reference materials. At the same time, LA-ICP-MS owes its success to being relatively insensitive to the matrix after accounting for differences in ablation yield. Analysing the fluids as a solid and sampling them by laser circumvents the usual dilution step. Fluid reference materials were prepared by adding the elements of interest to one of the crater lake fluid samples at known, but varying concentrations and by stepwise dilution of one of these fluids. Differences in ablation yield, resulting mainly from variations in the coupling of the laser with the sample, were accounted for by adding a known quantity of lithium as an internal standard. Working curves for both ICP-MS and LIBS were obtained for Al, Mg, Fe, Ca, K, Na, S and Cl, yielding relative trueness values for 4 crater lake samples of known composition of Al-7%, Ca-5%, Fe-1%, K < 1%, Mg-4%, Na-5%, S-3%, and Cl-6% for ICP-MS and Al-2%, Ca-9%, Fe-17%, K-10%, Mg-4%, Na < 1%, S-8%, and Cl-9% for LIBS. For these elements, ranging in concentration from around 400 mg/kg to 25 g/kg, LIBS yielded similar trueness results to ICP-MS. LIBS calibration without an internal standard produces acceptable results for Li only, allowing the cryo-LIBS to analyse the major elements while optimising the ICP-MS for trace-element analysis and obtaining a full suite of elements simultaneously without the need for sample dilution.

Analytical effect of stabilizer volume and shape on zircon U\u2013Pb dating by nanosecond LA-ICP-QMS

In this paper, we evaluated the effect of seven stabilizers with different shapes (including cylinder, cubic and ball shape) on zircon U–Pb dating analysis by laser ablation inductively coupled plasma quadrupole mass spectrometry (LA-ICP-QMS) in detail. In the case of stabilizer volume examined, the analytical efficiency of cylinder stabilizers (21.2, 25.1, 35.3 and 125 mL) were investigated in terms of signal stabilization, signal rising/washout time and U–Pb dating accuracy. By using zircon 91500 as reference material for external calibration, the 206Pb/238U age of zircon Plešovice was determined by a nanosecond LA-ICP-QMS, where the stabilizer was placed directly after the ablation cell and sample aerosols carried by helium passed through the stabilizer and subsequently mixed with make-up gas (argon) before ICP. It was found that transient signal oscillations were invisible and signal intensities were comparable using all the stabilizers, while signal rising time was 2.0-fold and washout time was 27.6-fold for stabilizer with volume of 125 mL to that of 21.2 mL. The obtained average 206Pb/238U age of zircon Plešovice was 335.53 ± 1.02, 361.73 ± 5.04, 340.10 ± 1.98 and 341.21 ± 5.17 Ma (2σ, n ≥ 5), respectively, giving average relative deviations of a single point of age (1σ) less than 2.0%. Among the corresponding 206Pb/238U ratios, it was also found that the value (0.05343 ± 0.87‰, 1σ, n = 5) obtained using 21.2 mL of cylinder stabilizer highly agreed with that of 0.05384 ± 0.74‰ (1σ, n = 5) using the commercially available “squid” stabilizer. The analytical efficiency of the 21.2 mL of cylinder stabilizer was then compared to that of cubic shape stabilizer (18.5 mL) and ball shape stabilizer (14.1 mL). Results showed that there were no significant differences of the obtained 206Pb/238U ages using stabilizers with volume in the range of 14.1–21.2 mL. But both cubic and ball shape stabilizers exhibited washout time over 270 s. We also studied the particle filter effect of the stabilizers by packing the 21.2 mL of cylinder stabilizer with 1.0 g of stainless wire. Despite the average 206Pb/238U age deviation was only − 0.81%, spiky signals occasionally occurred which might be ascribed to the use of a nanosecond laser and relatively low density of stainless wire in the stabilizer. This study confirmed that an empty stabilizer with volume of 21.2 mL and cylinder shape was preferred to produce smoothing signals. The improved analytical accuracy of zircon U–Pb dating using such a stabilizer ensured the future application to trace element analysis by LA-ICP-QMS.

Online solid-phase extraction−inductively coupled plasma–quadrupole mass spectrometric quantification of 90Sr using 88Sr/86Sr isotope dilution method

Due to the lack of a correlation with the natural Strontium (Sr) isotopes, it is difficult to apply the isotope dilution (ID) method to an artificial radioactive mononuclide Strontium-90 (90Sr), in inductively coupled plasma–quadrupole mass spectrometry (ICP–QMS). Meanwhile, online solid-phase extraction (SPE)−ICP−QMS (SPE−ICP−QMS) serves as an automatic sequential analytical technique for measuring the ultra-trace amounts of radionuclides; however, apparent assay values obtained using this method are often negatively affected by differences in the sample matrix composition between standard and actual samples. In this study, the pg L−1 level of 90Sr was successfully measured by combining online SPE−ICP−QMS and the ID method with 88Sr/86Sr ratios in one sample injection, without the radioactive standard. Although naturally occurring abundant isobaric 90Zr significantly influences 90Sr quantification during mass spectrometry, consecutive separations between automated SPE and dynamic reaction cell (DRC) oxidation enable 90Sr quantification, even in the presence of isobaric 90Zr (acceptable down to 5.7 × 10−9 of 90Sr/Zr in sample solution), using this method. Through this method, both radioactive 90Sr and naturally occurring Sr were simultaneously quantified using 88Sr-to-86Sr and 88Sr-to-90Sr ratios without radioactive 90Sr standard solutions. This simultaneous quantification of stable Sr and 90Sr was achieved within 15 min with good recovery rates. The limit of detection of 90Sr was 1.1 pg L−1 (equivalent to radioactivity 5.6 Bq L−1) for a 10 mL injection. Finally, water collected from an actual contaminated water storage tank at the Fukushima Daiichi Nuclear Power Plant (Fukushima, Japan) was analyzed using the proposed method, and the obtained results agreed well with those obtained using conventional analytical methods.

Quantifying Chemical Composition and Reaction Kinetics of Individual Colloidally Dispersed Nanoparticles

To control a nanoparticle's chemical composition and thus function, researchers require readily accessible and economical characterization methods that provide quantitative in situ analysis of individual nanoparticles with high throughput. Here, we established dual analyte single-particle inductively coupled plasma quadrupole mass spectrometry to quantify the chemical composition and reaction kinetics of individual colloidal nanoparticles. We determined the individual bimetallic nanoparticle mass and chemical composition changes during two different chemical reactions: (i) nanoparticle etching and (ii) element deposition on nanoparticles at a rate of 300+ nanoparticles/min. Our results revealed the heterogeneity of chemical reactions at the single nanoparticle level. This proof-of-concept study serves as a framework to quantitatively understand the dynamic changes of physicochemical properties that individual nanoparticles undergo during chemical reactions using a commonly available mass spectrometer. Such methods will broadly empower and inform the synthesis and development of safer, more effective, and more efficient nanotechnologies that use nanoparticles with defined functions.

Episodic Precipitation of Wolframite during An Orogen: The Echassières District, Variscan Belt of France

Monazite and rutile occurring in hydrothermally altered W mineralizations, in the Echassières district of the French Massif Central (FMC), were dated by U-Pb isotopic systematics using in-situ Laser ablation-inductively coupled plasma–quadrupole mass spectrometry (LA-ICP-MS). The resulting dates record superimposed evidence for multiple percolation of mineralizing fluids in the same area. Cross-referencing these ages with cross-cutting relationships and published geochronological data reveals a long history of more than 50 Ma of W mineralization in the district. These data, integrated in the context of the Variscan belt evolution and compared to other major W provinces in the world, point to an original geodynamic-metallogenic scenario. The formation, probably during the Devonian, of a quartz-vein stockwork (1st generation of wolframite, called wolframite “a”; &gt;360 Ma) of porphyry magmatic arc affinity is analogous to the Sn-W belts of the Andes and the Nanling range in China. This stockwork was affected by Barrovian metamorphism, induced by tectonic accretion and crustal thickening, during the middle Carboniferous (360 to 350 Ma). Intrusion of a concealed post-collisional peraluminous Visean granite, at 333 Ma, was closely followed by precipitation of a second generation of wolframite (termed “b”), from greisen fluids in the stockwork and host schist. This W-fertile magmatic episode has been widely recorded in the Variscan belt of central Europe, e.g. in the Erzgebirge, but with a time lag of 10–15 Ma. During orogenic collapse, a third magmatic episode was characterized by the intrusion of numerous rare-metal granites (RMG), which crystallized at ~310 Ma in the FMC and in Iberia. One of these, the Beauvoir granite in the Echassières district, led to the formation of the wolframite “c” generation during greisen alteration.

An Isotopic Study of Bio-accessible Lead in Wheat, Miswak Toothbrush and Miswak Fruit Using the Continuous On-line Leaching Method with Inductively Coupled Plasma Mass Spectrometry

In this study, sources of Pb are investigated using the 206Pb/207Pb isotopic ratio measured by inductively coupled plasma quadrupole mass spectrometry in the bio-accessible fractions from wheat, Miswak toothbrush (also used as chewing stick) and Miswak fruit. These samples were obtained for the in vitro batch and on-line leaching methods that mimic the human gastrointestinal tract by sequentially using artificial saliva, gastric juice and intestinal fluid for extraction. The two methods provided similar results according to a Student’s t-test at the 95% confidence level. Significant (p &lt; 0.05) differences in 206Pb/207Pb were noted at the 95% confidence level in different artificial body fluids. Except for unpolluted Miswak toothbrush and Miswak fruit, which only contained geogenic Pb, the samples contained a mixture of geogenic and anthropogenic Pb, with bio-accessible Pb in saliva being mainly from a geogenic source, whereas bio-accessible Pb in the stomach and intestinal fluids was mainly from anthropogenic sources. Despite the fact that leaded petrol was phased out in Saudi Arabia in 2001, a Miswak toothbrush collected on the side of a busy road after exposure for only a few days and Safeer wheat were still being contaminated with Pb and had an isotopic composition matching that of Pb added to petrol. The 208Pb/206Pb isotopic ratio for gastric bio-accessible Pb also matched that reported in tetraethyllead. The 206Pb/207Pb isotopic ratios of intestinal bio-accessible Pb from Qassim wheat and Safeer wheat point to coal combustion as the source. Overall, these results highlight the need for continued Pb monitoring and the value of examining bio-accessible fractions periodically to identify Pb sources.

Online Solid-Phase Extraction-Inductively Coupled Plasma-Quadrupole Mass Spectrometry with Oxygen Dynamic Reaction for Quantification of Technetium-99.

Quantification of pg/L levels (i.e., 0.6 mBq/L) of radioactive technetium-99 (99Tc) was achieved within 15 min in the presence of isobaric and polyatomic interference sources such as ruthenium-99 (99Ru) and molybdenum hydride (98Mo1H) at 3–11 orders of magnitude higher concentrations. Online solid-phase extraction–inductively coupled plasma–quadrupole mass spectrometry (ICP–QMS) with oxygen (O2) dynamic reaction cell (online SPE–ICP–MS–DRC) was shown to be a thorough automatic analytical system, circumventing the need for human handling. At three stepwise separations (SPE–DRC–Q mass filters), we showed that interference materials allowed the coexistence of abundance ratios of 1.5 × 10–13 and 1.1 × 10–5 for 99Tc/Mo and 99Tc/Ru, respectively. A classical mathematical correction using the natural isotope ratio of 99Ru/102Ru was used to calculate the residues of 99Ru. Using this optimized system, a detection limit (DL; 3σ) of 99Tc was 9.3 pg/L (= 5.9 mBq/L) for a 50 mL injection and sequential measurements were undertaken at a cycle of 24 min/sample. For the measurement of a lower concentration of 99Tc, an AG1-X8 anion-exchange column was used to study 20 L of seawater. Its DL was approximately 1000 times greater than that of previous methods (70.0 fg/L). Thus, this method withstands coexistences of 5.8 × 10–18 and 3.5 × 10–9 for 99Tc/Mo and 99Tc/Ru, respectively. Spike and recovery tests were conducted for environmental samples; the resulting values showed good agreement with the spike applied.

Study of Long-Term Determination Accuracy for REEs in Geological Samples by Inductively Coupled Plasma Quadrupole Mass Spectrometry.

This work presents the long-term determination accuracy study of ICP-QMS for rare earth elements (REEs) in geological matrices. Following high-pressure closed acidic decomposition, REEs are measured repetitively across seven months by ICP-QMS. Under optimum experimental conditions (including spray chamber temperature, gas flow rate, sampling depth, etc.), the REE contents in geological standard materials from basic (basalt BCR-2 and BE-N) to intermediate (andesite AGV-2) and up to acidic (granite GSR-1) show good agreement with the certified values, giving relative errors below 10%. Here, the influence of two storage materials (perfluoroalkoxy PFA and polypropylene PP) on the long-term determination accuracy of REEs has also been monitored. It is found that the relative errors of REEs using a PFA container range from −6.6 to 6.3% (RSDs < 6.0%), while that using a PP container are within −4.0 to 3.9% (RSDs < 4.6%). By using PP material as a solution storage container, the accuracy of REEs quantification in a series of real geological samples are checked, showing the RSDs of less than 5.0%. This work first clarifies the long-term stability of REEs quantification by ICP-QMS covering two types of storage materials, confirming the reasonability of PP material as a daily storage container in terms of higher data precision and lower cost.

Separation and determination of ultratrace rhenium quantities in molybdenum matrix

ABSTRACT The production of very pure molybdenum, free of Re even at ultratrace levels, is extremely important in meeting target purity specifications during the production of 99Mo for medical applications. Here we propose two methods for separating ultratrace levels of Re from a bulk Mo matrix using either solvent extraction or extraction chromatography, combined with inductively coupled plasma quadrupole mass spectrometry (ICP-MS) detection. Re is extracted (D > 70) from solutions in sulfuric acid as a complex with tri-n-butyl phosphate. Scrubbing and washing steps result in total decontamination factors for Mo up to 1,700 for solvent extraction and 3,500 for extraction chromatography. Re is stripped into a 3 M NH4OH matrix and analyzed by ICP-MS. Detection (LD ) and quantification (LQ ) limits were optimized by matrix-matching to allow detection of Re in strip solutions at levels of LD = 0.1 ng Re/g-Mo and LQ = 0.3 ng Re/g-Mo in Mo powder samples. By employing these two extraction methods, excellent recoveries of Re from bulk Mo are achieved, and the LQ is improved by a factor of 5 × 104.

An optimized HNO3 and HBF4 digestion method for multielemental soil and sediment analysis using inductively coupled plasma quadrupole mass spectrometry

A robust and reliable analytical procedure for the determination of trace (mg∙kg−1) and ultra-trace elements (μg∙kg−1) in soil and sediments by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) was optimized. Aliquots of ∼200 mg of two certified reference materials (IAEA Soil-7, soil and IAEA SL-1, lake sediments) were digested in nitric acid (HNO3) purified twice by sub-boiling distillation using a microwave-heated high-pressure autoclave. Incremental addition of tetrafluoroboric acid (HBF4, 0.1–2 mL) to HNO3 was evaluated for yield. The selection of appropriate proportions of digestion acids was crucial to obtain accurate results. Digested samples were analyzed for a range of trace elements including those that are potentially toxic (Ag, Cd, Pb, Sb, and Tl), plant micronutrients (Cu, Fe, Mn, and Zn), those enriched in bitumen (Mo, Ni, and V), and lithophile elements (Al, Ba, Co, Cr, Rb, Sr, Th, Ti, Y, and Zr). Nitric acid alone proved to be sufficient to completely liberate Cd, Co, Cr, Fe, Mn, Ni, Pb, V, and Zn in both soil and sediments (87%–120% recovery). For almost all the other elements, addition of HBF4 was needed for improved recovery. A combination of 3 mL of HNO3 and 1.5 mL of HBF4 was optimal to fully liberate an extended list of elements including Ba, Sb, and Sr from both the reference materials. Conservative lithophile elements (Th, Ti, Y, and Zr) could not be completely recovered with the proposed method, requiring hydrofluoric acid for complete dissolution of recalcitrant minerals.