Determination Of Isotope Ratios Research Articles

Application of Deep Learning to Spectroscopic Features of the Balmer-Alpha Line for Hydrogen Isotopic Ratio Determination in Tokamaks

We propose in this paper the use of artificial intelligence, especially deep learning algorithms, for the isotopic ratio determination for hydrogen–deuterium mixtures. Our approach is based on the Balmer-α line emitted by hydrogen and deuterium, but unlike the standard method, it does not consist of fitting the Hα/Dα line spectra. Instead, only some basic spectroscopic features such as the line peak-to-dip wavelength separation, peak-to-peak and dip-to-peak intensity ratios of the Zeeman–Doppler-broadened Hα/Dα line spectra are used by the regression algorithm for training. We demonstrate the proof-of-principle of our approach by applying deep learning from the open-access machine-learning platform TensorFlow to Hα/Dα line profiles, which we have synthetized with pre-determined parameters such as neutral temperatures, the magnetic field strength and the H/(H+D) isotopic ratio. The used regression algorithm allowed us to retrieve with a good accuracy the isotopic ratios used for the synthetized line profiles.

Scale Conversion and Uncertainty Calculations in Isotope Delta Measurements

Isotope ratio applications are on the increase and a major part of which are delta measurements, because they are easier to perform than the determination of absolute isotope ratios while offering lower measurement uncertainties. Delta measurements use artefact‐based scales and therefore scale conversions are required due to the lack of the scale defining standards. Such scale conversions often form the basis for comparing data being generated in numerous projects and therefore need to be as accurate as possible. In practice, users are tempted to apply linear approximations, which are not sufficiently exact, because delta values are defined by nonlinear relationships. The bias of such approximations often is beyond typical measurement uncertainties and its extent can hardly be predicted. Therefore, exact calculations are advised. Here, the exact equations and the bias of the approximations are presented, and calculations are illustrated by real‐world examples. Measurement uncertainty is indispensable in this context and therefore, its calculation is described as well for determining delta values but also for scale conversions. Approaches for obtaining a single delta measurement and for repeated measurements are presented. For the latter case, a new approach for calculating the measurement uncertainty is presented, which considers covariances between the isotope ratios.

Methods and benefits of measuring non-hydrocarbon gases from surface casing vents

Surface casing vents divert natural gas migration along oil and gas boreholes to bypass groundwater, with the gas venting to the atmosphere. While this strategy is designed to protect groundwater, it constitutes a source of greenhouse gases to the atmosphere. In instances where gas leakage occurs, the characterization of the molecular and isotopic composition of natural gas emitted from surface casing vent flows can be used to assist in identifying the gas source. We compare concentration measurements of non-hydrocarbon gases (within natural gas) of samples analyzed by laboratory-based gas chromatography (N2, Ar, CO2 and O2) and magnetic sector noble gas mass spectrometry (He, Ar and Kr) with field measurements conducted using a field portable quadrupole mass spectrometer (miniRUEDI). The standard deviation of miniRUEDI concentration results was within plus/minus one standard deviation of samples measured using laboratory-based GC (N2, O2, Ar and He) and magnetic sector noble gas mass spectrometry (He, Ar). Additional laboratory-based determination of isotope ratios of methane and argon (δ13CCH4, δ2HCH4, and 40Ar/36Ar) enabled a comparison between information provided by the analysis of reactive gases compared with noble gas isotopes. Gases from different sources displayed quantifiable differences in δ13CCH4 and δ2HCH4, but these changes may or may not be distinguished if only one sampling event is conducted. By comparison, 40Ar/36Ar further enabled the differentiation of various gas sources. The objective of this paper is to discuss the advantages and trade-offs of the three different analysis methods considered, and the feasibility of their application in different environmental monitoring scenarios.

Determination of lead isotope ratios by inductively coupled plasma mass spectrometry and comparison of lead isotope ratios among different samples

Determination of lead isotope ratios by inductively coupled plasma mass spectrometry and comparison of lead isotope ratios among different samples

Methods for the Determination of Stable Isotope Ratios of Multiple Nitrogen Species in Rainwater Using Distillation and Evaporation

Nitrogen (N) isotope ratios (δ15N) of multiple N species including ammonium (NH4+), nitrate (NO3−), dissolved organic N (DON), and total dissolved N (TDN) can serve as indicators of the sources of wet N deposition. However, methods for sequential analysis of these multiple N species are not well developed. In this study, methods for the determination of δ15N of these multiple N species were proposed through a traditional distillation method for NH4+ and NO3−, direct evaporation for TDN, and an isotope mass balance equation for δ15N-DON. A series of experiments were conducted 1) to find evaporation conditions including pH (<3.5 vs. 5.4) and evaporation methods (oven drying at 60 and 100°C, infra-red chamber, and freeze-drying), 2) to investigate precision and accuracy of distillation for δ15N of NH4+ and NO3−, and 3) to determine δ15N-TDN by direct evaporation and δ15N-DON with mass balance equation. (NH4)2SO4 (‒4.0 ± 0.03‰), KNO3 (‒4.2 ± 0.03‰), and CO(NH2)2 (‒5.4 ± 0.04‰) were used as reference materials for NH4+, NO3−, and DON, respectively. In this study, for the analysis of δ15N of NH4+ and NO3−, the conventional distillation method was tested in an effort to save cost for laboratories equipped with the distillation system. Evaporation using oven at 60°C (but not 100°C), infra-red chamber, or freeze-drier after acidification to < pH 3.5 prevented 14NH3 loss. Analysis of the δ15N-NO3− (‒4.4 ± 0.1‰ to ‒3.9 ± 0.5‰) was reliable for a wide range of N content (0.1–0.5 mg), but analytical errors for δ15N-NH4+ were as high as 2.1‰ when N content was small (e.g., 0.1–0.3 mg N) due to background contamination and potential interference by co-existing DON. Direct evaporation of solution containing NH4+, NO3−, and DON to dryness produced reliable δ15N-TDN with accuracy <0.15‰ and precision <0.21‰. However, the analytical errors of δ15N-DON were highly dependent on the content of co-existing NH4+ as well as DON content. Therefore, the proposed protocol can be applied for rainwater containing a high NH4+ concentration (>2.0 mg N L−1 assuming that 200 ml of sample is used for distillation).

THE METHOD FOR Cu AND Zn ISOTOPE RATIO DETERMINATION BY MC ICP-MS USING THE AG MP-1 RESIN

The isotopic composition of copper is of great interest for researchers in various fields of science, geochemistry and hydrology in particular, wherein the consideration is being given to the variations in the isotopic composition of the Earth’s crust, extraterrestrial matter, and water basins, as well as to the origin and transfer of matter. Zn isotopes appear to be promising for identifying the sources and pathways of the environmental pollution. The aim of this study involves the refinement and validation of the zinc and copper isotopic ratio determination methodology covering the whole process from sample digestion to MC ICP-MS measurements. For this reason, as well as to assess the suitability of the methodology for the analysis of environmental samples, Zn and Cu isotopic analysis of the BHVO-2, BCR-2 and AGV-2 USGS certified reference materials has been performed. The method for determination of Cu and Zn stable isotope ratios by multi-collector inductively coupled plasma mass spectrometry in environmental samples is developed. The application of the AG MP-1 resin with optimized layer parameters (resin bed height 3.5 cm, diameter 1 cm) provides the high-purity Cu and Zn fractions. The method is characterized by high throughput and adequate analytical figures of merit when using the standard-sample bracketing technique for mass bias correction. The procedural blanks related to chemical dissolution and ion exchange procedures are lower than 1 and 3 ng for Cu and Zn, respectively, assuring no blank effect on the isotopic composition of samples. The accuracy and precision obtained for Cu and Zn isotope measurements in the BHVO-2, BCR-2 and AGV-2 geological certified reference materials demonstrate good agreement with the reference values published.

Recent advances in MC-ICP-MS applications in Earth and environmental sciences: Challenges and solutions

• History, instrumentation of MC-ICP-MS and its up-to-date developments. • Introduction of various sampling methods including femtosecond laser ablation. • Role of CRMs in obtaining precise isotope ratios and elemental concentrations. • Technique with high potential for applications in Earth sciences and environment. The development of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in 1992 opened up new opportunities for geochemical, mineral exploration, and environmental studies. Recent developments in MC-ICP-MS and its hyphenation to techniques such as laser ablation including femtosecond laser sampling, advances in detection system and several other developments made MC-ICP-MS, one of the most versatile analytical techniques for the determination of isotopic compositions in several types of earth and environmental materials. Different studies in recent times indicated that MC-ICP-MS can routinely produce isotopic data that is similar in precision to those obtainable by secondary ion mass spectrometry (SIMS), sensitive high resolution ion microprobe (SHRIMP), and thermal ionization mass spectrometry (TIMS), with striking advantages such as relatively higher throughputs, ease of analysis as the source operates at atmospheric pressure, and possibility of sample introduction by other means such as laser ablation and chromatographic techniques. Recent studies demonstrate the decisive benefits of MC-ICP-MS analysis (both solution and laser ablation modes) not only isotopic ratio determinations, but also absolute element concentration determinations of several elements in the periodic table in different types of geological and environmental materials in terms of versatility, accuracy, precision and for improved spatial resolution. Laser ablation split stream (LASS) technique with ability to do dating, and capability to obtain isotopic and elemental information simultaneously in rocks and minerals on a single sampling event, when coupled to a second ICP-MS system (typically a quadrupole ICP-MS or a high resolution-ICP-MS) demonstrated its potential to become an important analytical tool in solving important problems, especially in geochemistry. The performance characteristics of MC-ICP-MS are compared with those of other similar analytical techniques such as TIMS, SHRIMP, and SIMS with recent examples. This review contains detailed descriptions of the development of MC-ICP-MS instrumentation, analytical procedures, reference materials, and focused applications in the area of geochemistry, mineral exploration, and environmental areas.

Direct isotopic analysis of solid uranium particulates on cotton swipes by microextraction-ICP-MS

Direct isotope ratio analysis of solid uranium particulates on cotton swipes was achieved using a solution-based microextraction technique, coupled to a quadrupole inductively coupled plasma - mass spectrometer (ICP-MS). This microextraction-ICP-MS methodology provides rapid isotopic analysis which could be applicable to nuclear safeguards measurements. Particulates of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) and uranyl fluoride (UO2F2) ranging from 6 μm to 40 μm in length were transferred to cotton swipes with a particle manipulator. The microextraction probe then delivers a 5% nitric acid (HNO3) solvent onto the swipe surface to extract the uranium species. The extracted sample is then delivered to the ICP-MS for isotopic determination. The majority of uranium signal (∼99% and ∼94% for UO2(NO3)2·6H2O and UO2F2, respectively) was detected in the first 15 s extraction, while subsequent extractions on the same location had low or no U signal, suggesting near complete removal of the solid uranium compounds from the swipe surface. Ten samples (for each of the uranium compounds), were analyzed for their isotopic composition. For UO2(NO3)2·6H2O, the determined isotope ratios resulted in a % relative difference (% RD) from the referenced isotope ratios of 0.97, 1.0, and 7.3% for 234U/238U, 235U/238U, and 236U/238U, respectively. The % RD of the UO2F2 isotope ratios were 1.9 and 0.60% for 234U/238U and 235U/238U, respectively. The preliminary limits of detection were determined to be 0.002, 0.4, and 60 pg for 234U, 235U and 238U, respectively This work demonstrates that microextraction ICP-MS is a rapid and sensitive method that could directly determine uranium isotope ratios of UO2(NO3)2·6H2O and UO2F2 particulates on cotton swipes.

A simple method for Ce–Nd separation using nano-NaBiO3: Application in the isotopic analysis of U, Sr, Pb, Nd, and Hf in uranium ores

U, Sr, Pb, Nd, and Hf isotope ratios can provide basic and important information of nuclear materials. We established a simple and efficient column chemistry method using nano-NaBiO3, as both oxidizer and adsorbent, to completely separate Ce from rare earth elements (REEs). This new method exhibited a high decontamination (Ce/Nd < 10−5) ability and was easy to conducted, thereby providing clear advantages compared to traditional liquid–liquid and solid phase micro-extraction techniques. Additionally, a rapid four-column separation procedure, based on Sr, TUR, Ln resins and nano-NaBiO3, was developed to isolate U, Sr, Pb, Nd, and Hf in ore samples. The entire procedure could be completed in 4–5 hrs. The robustness of the proposed method was demonstrated by analyzing the 235U/238U, 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 142Nd/144Nd, 143Nd/144Nd, and 176Hf/177Hf isotopic ratios of two certified reference materials (CRMs). The analytical results obtained using this method showed good agreement with previously published data. The feasibility of this method was extended to the determination of isotope ratios in uranium ores. The results obtained from the two samples with different regions indicated that they have different isotopic ratios information. These findings indicate the potential for the use of this new method in nuclear forensic science.

Determination of Isotope Ratio of Plumbum Pollution Source in Birmingham Urban Soils

Determination of Isotope Ratio of Plumbum Pollution Source in Birmingham Urban Soils

Accurate Determination of Zr Isotopic Ratio in Zircons by Femtosecond Laser Ablation MC-ICP-MS with \u201cWet\u201d Plasma Technique

This work evaluates the use of femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS) for Zr isotopic analysis in zircons. The mass fractionation caused by instrumental mass discrimination was corrected by a combination of internal correction using Sr as an internal standard (coming from a NIST SRM 987 standard solution) and external correction using a matrix-matched standard. Several important instrument parameters were investigated, such as the effect of the addition of N2 and “wet” plasma condition, the mass fractionation behaviors between Zr isotopes and Sr isotopes, the position effect in laser ablation cell and the effect of laser ablation parameters (laser spot size and energy density). The Zr isotope compositions of seven zircons (GJ-1, 91500, Plešovice, Rak-17, Paki, Aus and Mala) were determined by the developed fs-LA-MC-ICP-MS and thermal ionization mass spectrometry (TIMS). Our fs-LA-MC-ICP-MS results for Zr isotope compositions agreed with TIMS analyses within analytical uncertainties, indicating the presented method is a suitable tool to resolve isotopic zoning in natural zircons. The results also suggest that GJ-1, 91500, Plešovice, Paki, Aus and Mala had the homogenous Zr isotope composition and could be considered as the potential candidates for the Zr isotope analysis in zircons, except Rak-17 which presented the large Zr isotope variation.

Forensic Analysis of Artworks: More Than a (Complex) Analytical Issue

Forensic Analysis of Artworks: More Than a (Complex) Analytical Issue

Irradiated UAmO2 transmutation discs analyses: from dissolution to isotopic analyses

This paper details the different steps for the isotopic determination of UAmO2 discs from analytical irradiation. MARIOS and DIAMINO irradiations were performed in materials testing reactors to study the behaviour of americium bearing blanket samples in regard of heterogeneous recycling in sodium-cooled fast reactor. Six irradiated discs were dissolved in hot cells and were analyzed to determine isotope ratios of uranium, plutonium, americium and neodymium. The ratios were measured combining chemical separations and TIMS analyses. Using the double isotope dilution methodology helps measuring 238Pu/238U, 241Am/238U and 148Nd/238U ratios with uncertainty about a few per mil (k = 2).

Accurate and precise determination of the boron isotope ratio by QQQ-ICP-MS: application to natural waters and carbonates

This is a novel method for precise determination of the boron isotope ratio by QQQ-ICP-MS at a nanogram level of boron.

Improved uranium isotopic ratio determinations for the liquid sampling-atmospheric pressure glow discharge orbitrap mass spectrometer by use of moving average processing

Applying moving average processing to isotope ratio determinations collected using an LS-APGD source coupled with an Orbitrap MS increases the precision of the measurements and reduces the number of points needed to collect high precision data.

A precise and accurate analytical method for determination of osmium isotope ratios at the 1–15 pg level by using a MC-ICP-MS equipped with sparging introduction and high-sensitivity discrete dynode-type ion-counting detectors

Properly calibrated discrete dynode SEM ion-counting detectors and minimization of blank Os by an improved vial-cleaning method enables Os isotope analysis at the 1–15 pg level with high accuracy and precision.

Precise/small sample size determination of stable Cd isotope ratios of geological samples with double spike MC-ICP-MS

The modified chemical purification protocol and double spike Cd isotope method avoid using the toxic HBr to isolate Cd from Zn and show very high tolerance to the presence of Zn in the sample solutions.

Precise determination of lithium isotope ratios at the sub-nanogram level by QQQ-ICP-MS: application to natural waters and carbonates

Lithium isotopes are a powerful tracer of low and high temperature geochemical processes. Utilizing commonly available instrumentation (QQQ-ICP-MS), we have developed a novel method for precise determination of Li isotopes from sub-nanogram samples.

207Pb–206Pb возраст источников позднекайнозойских вулканических пород коро-мантийного перехода в соотношении с возрастом офиолитов и древних блоков, экспонированных на поверхности коры: трансект Китой–Байдраг Байкало-Монгольского региона

The results of determinations of Pb isotope ratios in Late Cenozoic volcanic rocks of the southwestern part of the Baikal rift system along the Kitoi-Baidrag transect are presented. The obtained 207Pb–206Pb estimates of the restite material incubation time in the springs are in good agreement with the Precambrian dating of ensembles of ancient continental blocks and ophiolite belts exposed on the Earth's surface. The sources are distinguished along the transect: the ancient Gargan block of the Tuva-Mongolian microcontinent (massif) with the Hadean protolith and Archean-Neoproterozoic events; Khangai and, possibly, Dzhida-Khangai slabs, and the ancient Baidrag block, a fragment of the Tarbagatai-Dzabkhan microcontinent. According by the dating of the sources, the tectonosphere of the early and middle mantle geodynamic epochs in the Baikal-Mongolian region included 3 layers: lower (proto-mantle), middle (mantle evolved), and upper (crust-mantle transition, CMP). In the Khangai continental domain, the protoliths of a wide Precambrian age range of sources were generally modified about 660 Ma ago. At the end of the Neoproterozoic and in the Early-Middle Phanerozoic, the mantle stabilized against the background of transformations of the ILC zone. In the tectonosphere of the latest geodynamic stage, the processes of transformation of three layers became active again: the proto-mantle, the evolved mantle, and the IMF.

The δ18O‐inferred thermal reconstruction for the Pleistocene based on the modification of existing glacial and interglacial paleoclimatic models

The determination of the climatic factors related to the Paleolithic archaeological, or fossils sites of the late Neogene and Quaternary periods would require the knowledge of all the fossil specimen's age-site-related paleoclimatic factors. Because the necessary high-temporal resolution georeferenced, paleoclimatic models do not exist for most of the periods of the Pliocene and Pleistocene epoch, at the first step, the former climatic conditions should be reconstructed according to the age-site pair data. The idea of the developed method is, that using the foraminiferal oxygen isotope (δ18O) ratio values, the available Pleistocene glacial and interglacial paleoclimatic model pairs can provide the bases for the reconstruction of the former thermal conditions for any period during the Pleistocene epoch. In a technical sense, the approach is based on the observation that the changes in the Cenozoic δ18O record can correspond with the global mean temperature alterations. Determining the cold and warm periods-related δ18O ratio values, new, georeferenced paleoclimatic models can be produced.The main steps of the developed method are as follows:•Determination of the oxygen isotope ratio (δ18O) which corresponds to the former thermal conditions of a site.•Using a scaling technique to create new, approximate climate maps by changing glacial and interglacial maps.•Reconstruction of the monthly mean temperature values based on the thermal conditions of the warmest and the coldest quarters.