BACKGROUND:In conventional MC-ICP-MS, Fe isotopic analysis is hindered by spectral interferences arising from both the Ar plasma (e.g., 40Ar16O+ on 56Fe+) and the sample matrix (e.g., Cr, Ni, and matrix effects). To overcome these limitations, we evaluated the recently developed MC-MICAP-MS, which uses an N2-based plasma, for direct measurement of 56Fe/54Fe isotopic composition in biological and environmental samples, combined with a novel fully automated purification procedure. RESULTS:The N2 plasma eliminates Ar-based interferences, enabling direct measurement of 56Fe/54Fe under low resolution conditions with intermediate precision of 0.07 ‰. CaN+ and KN+ interferences were negligible at Ca/Fe ≤ 0.01 and K/Fe < 0.1, while Na and Mg caused no significant matrix effects up to a matrix/Fe ratio of 1. Compared with other plasma-based techniques, MC-MICAP-MS provides a more robust approach for direct 56Fe/54Fe analysis. The automated purification method enabled unattended sample processing and yielded low, reproducible blanks (<5 ng), no carryover, high Fe recovery (98 % ± 8 %, 2 SD), and no significant on-column fractionation across bone, liver, hair, and river water matrices. Accuracy was confirmed using four biological and environmental reference materials. We propose δ56Fe/54FeIRMM014 values for NIST SRM 1400 of 0.06 ± 0.07 ‰, for GBW07601 of -0.14 ± 0.07 ‰, for GBW09101 of 0.06 ± 0.07 ‰, and for SLRS-6 of 0.44 ± 0.14 ‰. SIGNIFICANCE:Automated purification combined with MC-MICAP-MS provides a robust, reliable, and high-throughput approach for precise Fe isotopic analysis of biological and environmental samples, making it more accessible to a broader range of users.

The Skagerrak is the main depot center for organic matter and anthropogenic pollutants from the entire North Sea. Changes in ocean circulation or suspended matter supply might impact the sediment redox conditions. Indeed, little is known about the response of Skagerrak sediment and associated pollutants to different oxygen levels. We investigated sediments from three stations within the Skagerrak and incubated them for up to twelve months under aerobic and anaerobic conditions. Furthermore, we present the first δ98/95Mo data for Skagerrak sediment profiles and the incubations to be utilized as a redox tracer. The sediment profiles of metals reflected anthropogenic pollution (Cu, Ni, Pb) but differed regionally with redox conditions. We differentiated redox conditions mainly by sediment and porewater Fe, Mn, Mo and δ98/95Mo. In aerobic incubations, no Mn or Fe reduction was detected, while under anaerobic conditions, initial Mn and Fe reduction decreased after approximately three months. Under anaerobic conditions, a strong isotopic fractionation of Mo in the dissolved phase was found, reaching up to 5.03 ± 0.10‰, probably caused by incomplete thiolation of molybdate under low hydrogen sulfide levels. During the incubations, Cd, Cu, Ni, Pb were mobilized. While Cu and Cd were mobilized under aerobic conditions, Ni and Pb mobilization depended mainly on remineralization and redox conditions. Our results show that changes in oxygen conditions in the Skagerrak can have significant effects on the (legacy) metals stored in the sediment over the past decades.

Suspended particulate matter and associated pollutants from the entire North Sea are deposited in the Skagerrak, located between Norway and Denmark. Consequently, the sediments of the Skagerrak play a key role for long-term carbon storage within the North Sea. Due to its location and bathymetry, the bottom sediment redox conditions within the Skagerrak are heterogeneous and cover a wide range from oxic to suboxic conditions. We investigated nitrogen sequestration processes and the mobility of pollutants in these sediments during incubation experiments that simulated oxic and suboxic conditions. Analysis of isotopic fractionation was used as a tool to better understand the nitrogen sequestration pathways (δ15NO3-) and redox conditions (δ98/95Mo).Typically, incubation experiments last days to weeks but do not cover long-term effects. In contrast, we incubated different zones of three sediment cores with North Sea water for up to twelve months. The sediments originated from locations with (a) mainly iron reduction, (b) mainly manganese reduction and (c) both iron and manganese reduction. After one, three, six and twelve months, we sampled water and sediments from the incubations for various parameters (e.g., trace elements, carbon and nitrogen content, nutrients, δ15NO3-, δ98/95Mo). Under aerobic conditions, the sediments with high organic carbon content (2.78 ± 0.05 %) released up to 33 ± 6 µmol g‑1 NO3- during remineralization, while in anaerobic incubations, these sediments released only up to 4.8 ± 0.8 µmol g-1 NH4+. However, sediments with lower organic carbon contents (1.89 ± 0.05 %) released only 4.8 ± 1.2 µmol g‑1 NO3- and 1.18 ± 0.19 µmol g-1 NH4+, respectively. In combination with trace element concentrations, δ98/95Mo ratios allowed to distinct between different organic matter oxidation pathways. The aerobic incubations released mainly copper, lead and nickel while under anaerobic conditions, also cobalt but significantly less copper has been released. Hence, the prevailing oxygen conditions also have a strong impact on the remobilization of e.g., legacy pollutants stored in the sediments. The results of our long-term incubations reveal important biogeochemical processes and indicate that some processes are only traceable at larger timescales applied in this study, but not by incubation durations that are usually applied for biogeochemical studies.

Direct observation of proton emission for very small Q values is often unfeasible due to the long partial half-lives of the proton emission channel associated with tunneling through the Coulomb barrier. Therefore, proton emitters with very small decay energies may require the masses of both parent and daughter nuclei in order to establish them as proton unbound. Nuclear mass models have been used to predict the proton dripline of the thulium (Tm) isotopic chain (Z = 69), but until now the proton separation energy has not been experimentally tested. Mass measurements were performed using a multiple reflection time-of-flight mass spectrometer (MR-TOF-MS) at TRIUMF's TITAN facility to conclusively map the limit of proton-bound Tm. The masses of neutron-deficient 149Tm and 150Tm, combined with measurements of 149m,gEr (which were found to deviate from literature by approximate to 150 keV), provide the first experimental confirmation that 149Tm is the first proton-unbound nuclide in the Tm chain. Our measurements also enable determination of the strength of the N = 82 neutron shell gap at the Tm proton drip line, providing evidence supporting its continued existence.

Estimating the postmortem interval (PMI)-the time since death-remains a longstanding challenge in forensic and biological sciences due to the complex influence of environmental and physiological variables. Here, we present a novel computational framework that leverages the physical principles of radioactive decay to estimate PMI using the relative isotope abundances of radon progeny ([Formula: see text], [Formula: see text], and [Formula: see text]) in biological tissue. Our approach models the decay chain of inhaled [Formula: see text] and solves the associated system of differential equations to determine PMI based on isotope ratio dynamics. A key innovation is the use of paired measurements taken at two postmortem time points to capture the time-derivative of the decay curve, enhancing solution uniqueness, reducing dependence on prior exposure history, therefore minimizing error. Monte Carlo simulations were employed to assess model performance. If validated empirically, this approach lays the groundwork for a physics-based method for PMI estimation with potential applications in forensic science and radiation biology.

BACKGROUND:In conventional multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), major isobaric interference from 40Ar+ ions generated in the plasma prevents the direct measurement of 40Ca+ ions. To address this limitation, we investigated the performance of a microwave inductively coupled atmospheric-pressure plasma (MICAP) ion source, operating with N2 as plasma gas, recently integrated with multi-collector mass spectrometry (MC-MICAP-MS), for the measurement of 44Ca/40Ca and 44Ca/42Ca isotope abundance ratios. RESULTS:The use of a N2 plasma effectively eliminates Ar-related interferences, enabling direct measurement of 44Ca/40Ca and 44Ca/42Ca isotopic composition under low-resolution conditions with an intermediate precision of ≤0.10 ‰ (2 SD). The method exhibits high tolerance to K+ interference (Ca/K ratio ≥30), MgO+ interferences (Ca/Mg ratio ≥20), and Sr++ interferences (Ca/Sr ratio ≥350), which makes MC-MICAP-MS a more robust approach for the direct measurement of 44Ca/40Ca isotopic composition than other plasma-based methods such as cold plasma MC-ICP-MS and CRC-MC-ICP-MS. The accuracy was validated by comparison with data from established techniques obtained for four biological reference materials (bone, hair, and liver), showing consistent results. For the bovine liver reference material NIST SRM 1577c, we propose a δ44Ca/40CaSRM915a value of 0.50 ‰ ± 0.09 ‰ (U, k = 2) and a δ44Ca/42CaSRM915a value of 0.21 ‰ ± 0.07 ‰ (U, k = 2). SIGNIFICANCE:The MC-MICAP-MS approach offers a simple, robust, and reliable alternative for high-precision Ca isotope abundance ratio measurements that has the potential to significantly advance the applications of stable Ca isotope research in various fields.

Lung cancer mortality can be lowered through early-diagnostic screening of people demonstrating a ≥1.5 % 6-year risk of tumor development. However, many who develop lung cancer are ineligible for screening (∼40 % of Canadian patients) as they have insufficient tobacco smoking history. Tools to assess individual lung cancer risk based on exposure to other prevalent environmental carcinogens such as radon (222Rn) gas are lacking. Here, we explore ultrasensitive quantification of the 222Rn decay product 210Pb in toenails (n = 39) as an indicator of personalized, long-term radon exposure history. Toenail cuttings from adults inhaling elevated indoor radon in their primary house (average radon = 354.9 Bq/m3) over a mean of 26.5y (equating to 427 mSv radiation dose) contained 0.298 femtograms of 210Pb per nanogram of stable Pb. By contrast, only 0.075 femtograms 210Pb per nanogram Pb were detected in toenails from low radon exposure controls (28.4 Bq/m3 over 22.5y equating to 22.8 mSv) - a 397 % difference. Notably, elevated radon decay products (0.245 femtograms of 210Pb per nanogram Pb) persisted in toenails from highly radon-exposed people (545.6 Bq/m3 over 18.5y equating to 283 mSv) who, up to 6 years prior to toenail collection, had mitigated their primary residence to reduce radon (post-mitigation radon = 28.1 Bq/m3). No differences were detected on the basis of sex, age, tobacco smoking history, or 210Pb-rich game meat consumption. These data suggest that toenail 210Pb/Pb isotope (amount) ratios show promise for evaluating individualized retrospective radon dosimetry history - an approach that may become helpful to assess non-tobacco lung cancer risk in the future.

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A fully automated dual-column purification procedure for Zn from biological samples, designed for subsequent Zn isotopic analysis, is presented that utilizes the prepFAST MC™ system (Elemental Scientific), DGA resin (TrisKem International), and TK201 resin (TrisKem International). The procedure developed enables the unattended processing of 20 samples per day and is characterized by low and reproduceable blanks (< 1.5 ng), no carry-over or memory effect, high reusability (> 50 times), high Zn yields 100.1

The study focuses on optimizing a Laser Ablation Source (LAS) for use in mass spectrometry, particularly aiming to enhance transmission of ions and and determination of isotopic compositions in diverse matrices at TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN). Critical variables affecting mass spectrometer resolution, such as ion kinetic energy distribution and ion transport are optimized through LAS. The paper explores the importance of consistent initial conditions, ion transport efficiency, and ion capture for accurate and reproducible measurements. Using SIMION software, we optimized ion optical design to tackle challenges like collimating ions travelling off-axis and mass filtering. A significant part of the study is dedicated to ion optic design to enable low abundance measurement of ions of interest (e.g., 10 ions of interest out of 10 14 total ions). Techniques like high voltage switching and beam shaping were explored, and the final design aims for high transport efficiency and a 4 mm effective target scan area with maximum transport efficiency. The integration of LAS with a Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) is expected to yield an analytical tool with high spatial resolution and transport efficiency for isotope abundance measurement.

Following the reviews of atomic-weight determinations and other cognate data in 2015, 2017, 2019 and 2021, the IUPAC (International Union of Pure and Applied Chemistry) Commission on Isotopic Abundances and Atomic Weights (CIAAW) reports changes of standard atomic weights. The symbol Ar°(E) was selected for standard atomic weight of an element to distinguish it from the atomic weight of an element E in a specific substance P, designated Ar(E, P). The CIAAW has changed the values of the standard atomic weights of five elements based on recent determinations of terrestrial isotopic abundances:

New mass values measured with the TITAN MR-TOF-MS are reported for the short-lived isotopes 24−26Ne, produced at TRIUMF's ISAC facility using a uranium carbide target and cold FEBIAD ion source. A least-squares adjustment within the framework of the Atomic Mass Evaluation was performed and the improved precision of the new mass values is highlighted. The improved mass accuracy in this N=14 mid-shell region can also point to the refinement in values of the charge radii. By reducing the mass uncertainty of isotopes, their contribution of the mass shift uncertainty in laser spectroscopy can be negated. The work is part of developments for reaching the N=20 Island of Inversion, where high molecular contamination hinders mass measurements of the neon isotopes.

Abstract Following the reviews of atomic-weight determinations and other cognate data in 2015, 2017, 2019 and 2021, the IUPAC (International Union of Pure and Applied Chemistry) Commission on Isotopic Abundances and Atomic Weights (CIAAW) reports changes of standard atomic weights. The symbol A r°(E) was selected for standard atomic weight of an element to distinguish it from the atomic weight of an element E in a specific substance P, designated A r(E, P). The CIAAW has changed the values of the standard atomic weights of five elements based on recent determinations of terrestrial isotopic abundances: Ar (argon): from 39.948 ± 0.001 to [39.792, 39.963] Hf (hafnium): from 178.49 ± 0.02 to 178.486 ± 0.006 Ir (iridium): from 192.217 ± 0.003 to 192.217 ± 0.002 Pb (lead): from 207.2 ± 0.1 to [206.14, 207.94] Yb (ytterbium): from 173.054 ± 0.005 to 173.045 ± 0.010 The standard atomic weight of argon and lead have changed to an interval to reflect that the natural variation in isotopic composition exceeds the measurement uncertainty of A r(Ar) and A r(Pb) in a specific substance. The standard atomic weights and/or the uncertainties of fourteen elements have been changed based on the Atomic Mass Evaluations 2016 and 2020 accomplished under the auspices of the International Union of Pure and Applied Physics (IUPAP). A r° of Ho, Tb, Tm and Y were changed in 2017 and again updated in 2021: Al (aluminium), 2017: from 26.981 5385 ± 0.000 0007 to 26.981 5384 ± 0.000 0003 Au (gold), 2017: from 196.966 569 ± 0.000 005 to 196.966 570 ± 0.000 004 Co (cobalt), 2017: from 58.933 194 ± 0.000 004 to 58.933 194 ± 0.000 003 F (fluorine), 2021: from 18.998 403 163 ± 0.000 000 006 to 18.998 403 162 ± 0.000 000 005 (Ho (holmium), 2017: from 164.930 33 ± 0.000 02 to 164.930 328 ± 0.000 007) Ho (holmium), 2021: from 164.930 328 ± 0.000 007 to 164.930 329 ± 0.000 005 Mn (manganese), 2017: from 54.938 044 ± 0.000 003 to 54.938 043 ± 0.000 002 Nb (niobium), 2017: from 92.906 37 ± 0.000 02 to 92.906 37 ± 0.000 01 Pa (protactinium), 2017: from 231.035 88 ± 0.000 02 to 231.035 88 ± 0.000 01 Pr (praseodymium), 2017: from 140.907 66 ± 0.000 02 to 140.907 66 ± 0.000 01 Rh (rhodium), 2017: from 102.905 50 ± 0.000 02 to 102.905 49 ± 0.000 02 Sc (scandium), 2021: from 44.955 908 ± 0.000 005 to 44.955 907 ± 0.000 004 (Tb (terbium), 2017: from 158.925 35 ± 0.000 02 to 158.925 354 ± 0.000 008) Tb (terbium), 2021: from 158.925 354 ± 0.000 008 to 158.925 354 ± 0.000 007 (Tm (thulium), 2017: from 168.934 22 ± 0.000 02 to 168.934 218 ± 0.000 006) Tm (thulium), 2021: from 168.934 218 ± 0.000 006 to 168.934 219 ± 0.000 005 (Y (yttrium), 2017: from 88.905 84 ± 0.000 02 to 88.905 84 ± 0.000 01) Y (yttrium), 2021: from 88.905 84 ± 0.000 01 to 88.905 838 ± 0.000 002

The performance of high-precision mass spectrometry of radioactive isotopes can often be hindered by large amounts of contamination, including molecular species, stemming from the production of the radioactive beam. In this paper, we report on the development of Collision-Induced Dissociation (CID) as a means of background reduction for experiments at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). This study was conducted to characterize the quality and purity of radioactive ion beams and the reduction of molecular contaminants to allow for mass measurements of radioactive isotopes to be done further from nuclear stability. This is the first demonstration of CID at an ISOL-type radioactive ion beam facility, and it is shown that molecular contamination can be reduced up to an order of magnitude.

High-accuracy mass measurements of neutron-deficient Yb isotopes have been performed at TRIUMF using TITAN's multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). For the first time, an MR-TOF-MS was used on line simultaneously as an isobar separator and as a mass spectrometer, extending the measurements to two isotopes further away from stability than otherwise possible. The ground state masses of ^{150,153}Yb and the excitation energy of ^{151}Yb^{m} were measured for the first time. As a result, the persistence of the N=82 shell with almost unmodified shell gap energies is established up to the proton drip line. Furthermore, the puzzling systematics of the h_{11/2}-excited isomeric states of the N=81 isotones are unraveled using state-of-the-art mean field calculations.

The controlled focusing and transport of ion beams is of paramount importance in particle accelerators, high energy beamlines, and detector systems, as it determines the sensitivity and resolution of the instruments. Therefore, it is essential to model the beam dynamics before the commissioning of new instruments in order to optimise properties such as transmission and energy spread. In this paper, a commercial Plasma Ion Source (PIS), comprised of a heated filament and anode followed by its collimating optics, was modelled using Monte Carlo simulations run with the commercial software SIMION. The simulations were performed for the integration of the source within the existing ion transport optics of TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). Optimising the voltage configurations using these simulations proved successful in the commissioning of the PIS operated in surface ionisation mode at the TITAN experiment. A Time-of-Flight (TOF) mass spectroscopy method was developed which allowed for the identification of species ionised by the source. The integration of a flexible ion source into the TITAN experiment will open up new opportunities to perform Isotopic Ratios Mass Spectrometry (IRMS) measurements at TITAN.

Ca isotopes have gained increasing interest as a diagnostic tool for bone diseases due to the variations in abundances as a consequence of changes in bone-mineral balance. Optimized Ca/matrix separation prior to analysis is a prerequisite for reliable isotope ratio measurements in complex biological matrices such as blood, serum, or urine. The online analysis of analyte/matrix separation by ICP-MS enables direct assessment of elution profiles supporting the optimization process. The integration of transient signals and signal suppression challenge the quantification and interpretation of the elution profiles. Mn and Co remain unretained by the DGA Resin (TrisKem International) from nitric acid. Hence, in the present study, these elements were investigated for their application as standards to monitor signal suppression. Successful analyte quantification was accomplished using a dynamic correction strategy applying a linear gradient of a suppression factor based on Mn and Co intensities. An optimized Ca/matrix separation procedure using DGA Resin is proposed based on the results during online ICP-MS analysis. Graphic abstract

The application of Ca isotopic analysis in biomedical studies has great potential to identify changes in Ca metabolism and bone metabolism. Reliable measurement of Ca isotope-amount ratios is challenging considering limited Ca amounts and significant procedural blank levels. In this study, Ca purification was performed using the DGA Resin, optimized for low procedural blanks and separation of Ca from matrix elements and isobaric interferences (Na, Mg, K, Ti, Fe, Ba), while maintaining quasi-quantitative recoveries which are sufficient since a 42Ca–48Ca double-spike (DS) was applied. Ca isotopic analysis was performed using multicollector thermal ionization mass spectrometry (MC TIMS). The obtained procedural Ca blank of ≤10 ng enables processing of limited Ca amounts down to 670 ng. Data reduction of the measured Ca isotope-amount ratios was performed using an in-house developed software solving the DS algorithm. Data quality was improved by extension of equilibration time of the sample-DS mixture and implementation of a normalization strategy for raw isotopic data. The reported δ(44Ca/40Ca)NIST SRM 915a of NIST SRM 915a processed as a sample was found to be 0.01 ‰ ± 0.08 ‰ (2 SD, n = 15). Ca isotope-amount ratios of the reference material NIST SRM 1400 (bone ash), NIST SRM 1486 (bone meal), GBW07601 (human hair), and IAPSO (seawater) were in good agreement within uncertainty with literature data. Novel data on additional reference materials for biological tissues (hair) is presented, which might indicate a potential fractionation of Ca incorporated into hair tissue when compared to the blood pool.

A new series of neutron-rich indium mass measurements is reported from the TITAN multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). These mass measurements cover In125-134 (N = 76-85) and include ground states as well as isomeric states. The masses of nuclei in this region are known to be of great importance for accurately modeling r-process nucleosynthesis, and the significance of the reported neutron-rich indium masses is discussed in this context. Results are compared with earlier experimental data where available as well as theoretical mass models. The measurements reported here include the first mass measurements of In-133,In-134, as well as the first direct mass measurement of In-132. The masses of In125-131 ground states and several isomers were previously measured to higher precision by Penning trap mass spectrometry, which also resolved some low-lying isomers that could not be resolved in this work. The earlier Penning trap measurements serve as excellent cross-checks for the MR-TOF-MS measurements, and in some cases the MR-TOF-MS measurements improve the literature uncertainties of higher-lying isomer masses and excitation energies. A new isomeric state for In-128, I recently reported for the first time by the JYFLTRAP group, is also confirmed by the TITAN MR-TOF-MS, with a measured excitation energy of 1813(17) keV.