•A single GC method was proposed for analysis of volatile compounds in PET tracers.•Quantitation of solvents could be performed at ethanol concentration of up to 11 m/m%.•Base deactivated silica wool ...is recommended for packaging material of inlet liner.•The validation was performed according to Q2(R2)/Q14 ICH guideline.•Solvents were determined in 11Cmethionine, 11Ccholine, 18FFDG and 18FFET.
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A novel gas chromatography (GC) method for quantitation of volatile organic compounds (VOCs) in 18F- and 11C-radiopharmaceuticals listed in the European Pharmacopoeia (Ph. Eur.) was proposed. Optimized chromatographic parameters were used for separation of ethanol, acetone, acetonitrile, tetrahydrofuran (THF), dibromomethane (DBM), 2-dimethylaminoethanol (deanol), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) which could be detected in radioactive drug samples. The calculated peak resolutions (RS) were higher than 2.0 at ethanol concentration of up to 11 m/m%. Reproducible results could be obtained using base deactivated fused silica wool as packing material of inlet liner. Validation parameters showed excellent linearity (r2 ≥0.9998) in the range from 10 to at least 120% of concentration limit of solvents. The accuracy was determined as recovery of concentrations which ranged from 99.3% to 103.8%. Additionally, the relative standard deviation (RSD) of each solvent for inter-day and intra-day precision were in the range of 0.5–4.2% and 0.4–4.4%, respectively. The limit of quantitation (LOQ) for ethanol, acetone, acetonitrile, THF, DBM, deanol, DMF and DMSO was 0.48, 0.42, 0.43, 0.46, 4.35, 0.73, 0.68 and 0.50 mg/L, respectively. The developed procedure was successively applied for quantitation of ethanol, acetone, acetonitrile and deanol in radioactive drug samples of 11Cmethionine, 11Ccholine, 2-deoxy-2-18Ffluoro-D-glucose (18FFDG) and O-(2-18Ffluoroethyl)-L-tyrosine (18FFET). The proposed GC method applying flame ionization detection (FID) could be adapted in routine quality control of most frequently used positron emission tomography (PET) radiopharmaceuticals to perform the determination of residual solvents with analysis time of 12 min
The oceanic anoxic event in the Early Toarcian, often referred to as the ‘Torcian Oceanic Anoxic Event’, led to widespread deposition of organic‐rich black shales and geochemical anomalies in ...elemental distribution and multiple isotope systems in the Early Jurassic ocean. Best characterized by its hallmark carbon isotope anomaly, the event is widely regarded as a prime example of rapid greenhouse warming‐related changes in the Mesozoic Earth system. However, despite numerous studies, details of its forcing mechanisms, exact duration and the role of regional effects remain debated. This article presents new data (high‐resolution organic carbon isotope, calcareous nannofossil and elemental geochemical analyses) from the black shale‐bearing Lower Toarcian section in the Réka Valley, Hungary, with the aim of assessing any regional differences in the sedimentary and geochemical record and their bearing on the underlying oceanographic and climatic processes. Following a short segment with a positive trend at the base of the section, values of the carbon isotope data here are turning to a negative trend with a steep, stepwise drop in two negative shifts, reaching their minimum before a positive trend with oscillations characterizing the top part of the section examined. The shape of the curve and nannoplankton biostratigraphy (recognition of zones NJ5b, NJ6 and NJ7) allow reliable correlation of these data with the global carbon isotope perturbation recorded elsewhere in the Early Toarcian. It is proposed here that it would be fitting to rename the Torcian Oceanic Anoxic Event as the ‘Jenkyns Event’, to honour the seminal contributions of Hugh Jenkyns. The cyclostratigraphic analysis in this study suggests that the duration of the negative isotope excursion at Réka Valley is 200 kyr, 350 kyr or 1 Myr, depending on which astronomical forcing parameter controls the most prominent cyclicity. Spectroscopic analyses suggest that the source of the organic matter, marine algae according to previous studies, did not change considerably during the main negative carbon isotope excursion. The variability observed in major element concentrations and enrichments relative to the average shale in the Réka Valley black shales can be regarded as mixtures of terrigenous aluminosilicates and calcium carbonate as two endmembers. Consequently, the terrigenous compositional endmember of the studied black shales consists of a mixture of an illitic/smectitic and a kaolinitic clay, which supports previous suggestions of increased weathering under extremely humid climate in the hinterland during the Jenkyns Event.
The Valanginian positive carbon isotope excursion and associated environmental changes, known as the Weissert Event, is the first in the series of Cretaceous Earth system perturbations. Here, we ...develop a multiproxy cyclostratigraphy from a 31.2-m-thick Upper Valanginian to lowermost Hauterivian section of the Bersek Marl Formation in Gerecse Mountains, Hungary, comprising alternating marlstone layers of varying clay and carbonate content. The bulk carbonate δ13C signal shows sustained, elevated values (up to 2.7‰) up to 19.2 m, followed by a decreasing trend upsection. Together with biostratigraphic data, this suggests that the lower part of the section was deposited during the plateau phase of the Late Valanginian Weissert Event. Spectral analyses of the multiproxy dataset, including magnetic susceptibility measurements and gamma-ray spectroscopy on the lower part of the section, led to the identification of precession, obliquity, and long and short eccentricity signals. A mean sedimentation rate of 14 m/Myr was calculated based on astronomical tuning. The cyclicity in the proxy signals reflects dilution cycles induced by the fluctuating rate of detrital runoff into the basin. This supports the idea that orbitally-forced humid-arid cycles controlled the pelagic alternating sedimentation during the Early Cretaceous throughout the Tethyan area.
•Magnetic susceptibility, gamma ray, δ13C, and δ18O data from the Bersek Formation.•A new western Tethyan record of the Late Valanginian Weissert Event is described.•Spectral analysis reveals presence of Milankovitch periodicities in proxy signals.•Dilution cycles control the sedimentation and the proxy signals.•Minimum duration of the δ13C plateau of the Weissert Event is 1.25 Myr long.
High-precision analysis of the excess abundance (relative to the stochastic distribution) of mass 48 isotopologues in CO2 evolved from acid digestion of carbonates (∆48) has not been possible until ...recently due to the relatively low natural abundance of 18O. Here we show that the 253 Plus™ gas source mass spectrometer equipped with Faraday cups and 1013 Ω resistors can perform combined ∆47 and ∆48 analyses on carbonates with external reproducibilities (1SD) of 0.010 ‰ and 0.030 ‰, respectively.
~10 mg aliquots of five carbonate reference materials (ETH 1, ETH 2, ETH 3, ETH 4, and Carrara) are digested with phosphoric acid at 90 °C using a common acid bath. The evolved CO2 is purified using an automated gas preparation system (including cryotraps and a GC) and analyzed for its ∆47 and ∆48 compositions using the dual inlet system of a 253 Plus™ gas source mass spectrometer. Raw ∆47 and ∆48 values are finally normalized to the Carbon Dioxide Equilibrium Scale (CDES).
In ∆47, CDES 90°Cvs. ∆48, CDES 90°C space, calcite reference materials Carrara, ETH 3 and ETH 4 agree with the equilibrium curve for calcite after adding semi-empirically determined 90 °C acid fractionation factors of 0.196 ‰ (for ∆47) and 0.136 ‰ (for ∆48) to theoretical ∆63 and ∆64 data. Agreement between measured and theoretically expected ∆48, CDES 90°C highlights the accuracy of our high-precision clumped isotope analytical setup. Combined analysis of the abundances of mass 47 and mass 48 isotopologues in CO2 evolved from acid digestion of natural carbonates has excellent potential for the determination of accurate and highly precise paleotemperatures as well as for the identification of rate-limiting kinetic processes involved in biomineralization. A formation temperature of 15(±2) °C is obtained on the 95 % confidence level for the Upper Cretaceous chalk sample ETH 3.
Abstract
Surface temperature is a fundamental parameter of Earth’s climate. Its evolution through time is commonly reconstructed using the oxygen isotope and the clumped isotope compositions of ...carbonate archives. However, reaction kinetics involved in the precipitation of carbonates can introduce inaccuracies in the derived temperatures. Here, we show that dual clumped isotope analyses, i.e., simultaneous ∆
47
and ∆
48
measurements on the single carbonate phase, can identify the origin and quantify the extent of these kinetic biases. Our results verify theoretical predictions and evidence that the isotopic disequilibrium commonly observed in speleothems and scleractinian coral skeletons is inherited from the dissolved inorganic carbon pool of their parent solutions. Further, we show that dual clumped isotope thermometry can achieve reliable palaeotemperature reconstructions, devoid of kinetic bias. Analysis of a belemnite rostrum implies that it precipitated near isotopic equilibrium and confirms the warmer-than-present temperatures during the Early Cretaceous at southern high latitudes.
Analyzing the triple oxygen isotope (Δ′17O) composition of carbonates and air CO2 can provide valuable information about Earth system processes. However, accurately measuring the abundance of the ...rare 17O‐bearing CO2 isotopologue using isotope ratio mass spectrometry presents significant challenges. Consequently, alternative approaches, such as laser spectroscopy, have been developed. Here, we describe an adaptable dual inlet system for a tunable infrared laser direct absorption spectrometer (TILDAS) that maintains stable instrumental conditions for subsequent sample and reference measurements. We report ∆′17O measurements on three types of samples: reference CO2, CO2 derived from the acid digestion of carbonates, and air CO2. The external repeatability (±1σ) for reference‐sample‐reference bracketing measurements is generally better than ±10 ppm, close to the average internal error of ±6 ppm. Our results demonstrate that laser spectroscopy is a capable technique for measuring triple oxygen isotopes with the precision required to resolve variations in the ∆′17O values of air CO2 and to use the ∆′17O of carbonates for paleothermometry.
Plain Language Summary
Tunable infrared laser direct absorption spectroscopy (TILDAS) is a technique that determines isotopologue abundances by shining a laser through the analyzed gas and measuring the amount of light absorbed. Laser spectroscopy is emerging as a competitive alternative to the more common isotope ratio mass spectrometry due to its ability to provide rapid and precise measurements of rare isotope ratios directly on CO2 gas. We present a cost‐effective dual inlet system for TILDAS to measure the triple oxygen isotope composition of carbonates and air CO2. Our setup maintains stable measurement conditions, for example, instrumental temperature, gas composition, pressure, and achieves external repeatability generally below ±10 ppm. Triple oxygen isotope measurements with such precision enable resolving variations in the 17O‐anomaly of air CO2 and using the ∆′17O values of carbonates for paleoenvironmental applications.
Key Points
An inlet system using inexpensive hardware and open‐source software was developed for tunable infrared laser absorption spectroscopy
Spectroscopic measurements of ∆′17O in CO2 can be negatively influenced by variable temperatures, uneven CO2 mixing, which were addressed
The external standard deviation of repeated ∆′17O measurements of CO2 from carbonates and air was better than 10 ppm
A kapcsoltizotóp-geokémia (clumped isotope geochemistry), egy olyan új, dinamikusan fejlődő kutatási módszer, amely a 13C és a 18O izotópok egy molekulán belüli kapcsolódásának hőmérsékletfüggésén ...alapszik. Segítségével a karbonátok kiválási hőmérséklete nagy pontossággal meghatározható, kizárólag a karbonát fázis kapcsolt izotóp értéke (∆47) alapján. A paleoklimatológiai alkalmazások mellett a módszer a geológiai kutatások számos területén (pl. paleo-oceanográfia, atmoszféra-kutatás, rezervoár-geológia, geomorfológia, tektonika, diagenezis, biogeokémia, alacsony hőmérsékletű metamorf folyamatok, meteorit-kutatás, stb.) alkalmazható, és a műszerfejlesztések révén az alkalmazások köre folyamatosan bővül. A cikk röviden áttekinti a kapcsolt izotópos módszert, bemutatva annak alapjait, a rendelkezésre álló kalibrációkat, a lehetséges alkalmazási területeket és a témában eddig megjelent publikációkat.
In this study, we investigated Early Cretaceous (Valanginian, ca. 135 million years ago) climate from subtropical to boreal palaeolatitudes. Combined carbonate clumped isotope and oxygen isotope data ...derived from sub-arctic, boreal, and sub-tropical fossil belemnite rostra (Mollusca: Cephalopoda) provide new palaeotemperature estimates as well as a constraint on the oxygen isotope composition of seawater. Our belemnite data reveal balmy high-latitude marine temperatures (ca. 22 °C) and warm sub-tropical temperatures (ca. 31 °C). Supplementing our clumped isotope-based temperature estimates with published TEX86 data results in a conservative reconstruction of a latitudinal temperature gradient that is reduced compared to modern conditions. We find that modelling efforts are close to reproducing tropical temperatures when high pCO2 levels are considered. Warm polar temperatures imply, however, that data-model discrepancies remain. Early Cretaceous seawater oxygen isotope values show a modern profile and are much more positive (up to 1.5‰ SMOW) than typically assumed. Based on our findings, if the positive Cretaceous seawater δ18O values are not considered, carbonate δ18O thermometry would underestimate temperatures, most acute at middle and tropical latitudes.
•Early Cretaceous clumped isotope temperatures are 27(±4) °C and 19(±2) °C for tropical and polar latitudes, respectively.•Data-model discrepancies remain at higher latitudes for the Early Cretaceous.•Early Cretaceous seawater oxygen isotope values show a modern profile and are more positive than typically assumed.
A geológia számára alapvető a Föld folyamatai időbeliségének feltárása, a földtörténeti múltbeli változások között pedig ma kitüntetett jelentőségű az éghajlatváltozások megismerése. Éppen száz éve, ...1920-ban fektette le Milutin Milanković a Földet érő napsugárzás csillagászatilag meghatározott változásainak matematikai alapjait. A Milanković-ciklusok, vagyis a Föld pályaelemeinek periodikus változásai által vezérelt klímaciklusok üledékes kőzetekben rögzült nyomai nak vizsgálatával foglalkozó ciklussztratigráfia egyszerre nyújt lehetőséget a földtörténeti idő mérésére (asztrokronológia), illetve a paleoklíma rekonstrukciójára. Bár a szakterület nemzetközi irodalma igen gyors ütemben gyarapodik, korszerű módszereinek alkalmazása Magyarországon mindeddig szűk körű maradt, ezért elterjedését ezzel a szemlével kívánjuk segíteni. Áttekintést adunk a precessziós, tengelyferdeségi és excentricitási ciklusokról és a Föld éghajlatára gyakorolt hatásukról. Számba vesszük azokat a litológiai, paleontológiai, fizikai és geokémiai adatsorokat, amelyek a ciklussztratigráfiai elemzés alapjául szolgálhatnak. Lépésről lépésre tárgyaljuk az adatelőkészítés, spektrálanalízis, ciklusazonosítás és -értelmezés menetét és az eredmények ábrázolásának módjait, melynek végén kormodell állítható elő.Mind ez különböző szoftverkörnyezetben történhet, például az ingyenesen elérhető és felhasználóbarát Acycle program segítségével. Képet adunk a magyarországi képződmények ciklussztratigráfiai vizsgálatának történetéről, kitérve a korábban alkalmazott módszerekre. Rövid nemzetközi kitekintésünk példákat ad az időskála pontosítását segítő asztro kronológiai alkalmazásokról, különböző üledékképződési környezetek ciklusos képződményeinek vizsgálatáról és a paleoklimatológiával való elválaszthatatlan kapcsolatról. Nem kétséges, hogy a modern ciklusztratigráfia módszereinek bővü lő hazai alkalmazása további izgalmas rétegtani, szedimentológiai és paleoklimatológiai eredményekhez vezethet.
Kinetic isotope effects occurring during carbonate precipitation impact the accuracy of paleoclimate records. One rate-limiting process is CO2 absorption, which, at high pH, primarily proceeds ...through hydroxylation, where aqueous CO2 and OH− react to form HCO3−. In this study, we investigated the triple oxygen isotope fractionation (18O/16O and 17O/16O) associated with the hydroxylation reaction. We experimentally determined the extent of the kinetic isotope effects superimposed on the reacting CO2 and OH− during hydroxylation, using high-pH precipitation reactions. These results were compared to the equilibrium triple oxygen isotope fractionation between H2O and OH− modeled using quantum chemical computations.
Our quantum chemical modeling confirms the previously suggested equilibrium θeq.H2O/OH- of 0.5296 at 25 °C. Our empirical data show a kinetic isotope effect superimposed on the OH− involved in the hydroxylation reaction of approximately −16.4‰ for the fractionation of 18O/16O and a corresponding slope of 0.514 in triple oxygen isotope space. The θeffectiveH2O/OH- for the fractionation between water and the reacting OH− is 0.523.
In order to identify and potentially correct kinetic isotope effects in carbonates, it is important to understand the fractionations occurring during precipitation. Our results enable a more accurate modeling of kinetic isotope effects in triple oxygen isotope space, particularly the slope of hydroxylation. The θhydroxylation is dependent on the isotope composition of the ambient water, CO2, and the temperature. We estimate that θhydroxylation is approximately 0.532 for carbonates growing in 25 °C seawater.
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•Kinetic isotopes effects are superimposed on OH− and CO2 during CO2 hydroxylation.•We quantified the fractionations via experiments and theoretical modeling.•Our results estimate the hydroxylation slope in triple oxygen isotope space.
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