Isotopic Abundance Ratios Research Articles

A non-thermal method to maintain alkali vapor density of anti-relaxation coating cell in spin exchange relaxation-free magnetometer

The long-term stability of alkali metal vapor cell density is crucial for the performance of Spin Exchange Relaxation-Free (SERF) magnetometers. This paper addresses the issue of atomic density consistency commonly encountered with OTS and paraffin coatings in current quantum magnetometers. For the first time, the LIAD non-thermal method is applied to SERF magnetometers to maintain the long-term stability of alkali metal density. The study identifies the critical roles of desorption light luminous flux and integrating sphere uniformity in enhancing LIAD effectiveness. A new model based on the absorption spectrum of 85Rb and 87Rb was developed, achieving an R-square value of 0.989 and revealing a rubidium isotopic abundance ratio of 2.8:1, with OTS-coated cells showing the highest density retention. These findings contribute to the advancement of cryogenic SERF magnetometers by providing a deeper understanding of LIAD mechanisms and offering a viable alternative to thermal density control methods.

Applications of zinc stable isotope analysis in environmental and biological systems: a review

Zinc (Zn) is an essential trace element that is involved in both biotic and abiotic processes in Earth's surface environments. Over the last 20 years, advances in mass spectrometry instrumentation have enabled unprecedented high-precision Zn isotope abundance ratio determinations in natural and anthropogenic samples. Supported by a solid theoretical background inherited from the traditional non-metal stable isotopes (C, N, H, O, S), the understanding of the controlling factors of Zn isotope fractionation has rapidly evolved. In this article, we review the main applications and findings of Zn isotopes in a variety of scientific domains, including metal contamination, magmatic differentiation, plant uptake, weathering, global climate change, dietary and trophic chains, and biomedicine. The analytical aspects of Zn isotope determination in solid and water samples and the principles and mechanisms of Zn isotope fractionation are also reviewed. This work aims to provide a general yet in-depth panorama of Zn isotope chemistry and to demonstrate the versatility and potential of this isotope system for studying the biological, geological and chemical cycling of Zn.

Stable isotopes of landfast sea ice as a record of La Grande River under-ice plume dispersal

Vertical profiles of salinity, and isotopic abundance ratios of hydrogen (δ2H) and oxygen (δ18O) of 18 landfast ice cores, collected along the northeast coast of James Bay in March 2019, and one ice core collected in Belcher Islands, were used to obtain the winter timeseries of the spatiotemporal evolution of the under-ice plume of La Grande River (LGR), the dominant river in the area. Variability in the isotopic composition and salinity of the ice cores indicated changes to the water source composition at the ice–water interface when the ice layers formed. The increased presence of river water beneath the ice during January–March was marked by more negative isotopic ratios in the lower portion of the ice as river discharge was increased for hydroelectric production. River water was the source of ∼43% of the ice in our ice core samples ( n = 320) with the interquartile range from 16% to 71%. The river water fractions incorporated into the ice indicate that LGR under-ice plume extended more than 75 km north and at least 30 km south of the river mouth for ∼3 months. These findings correspond well with more challenging to obtain hydrographic observations. End-of-winter ice core sampling and analysis for isotopic abundance has potential as a tool to monitor dispersal of LGR discharge into the ice-covered coastal environment.

Physical properties of the southwest outflow streamer in the starburst galaxy NGC 253 with ALCHEMI

Aims. The physical properties of galactic molecular outflows are important as they could constrain outflow formation mechanisms. In this work, we study the properties of the southwest (SW) outflow streamer including gas kinematics, optical depth, dense gas fraction, and shock strength through molecular emission in the central molecular zone of the starburst galaxy NGC 253. Methods. We imaged the molecular emission in NGC 253 at a spatial resolution of 1.6″(∼27 pc at D ∼ 3.5 Mpc) based on data from the ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (ALCHEMI) large program. We traced the velocity and velocity dispersion of molecular gas with the CO(1–0) line and studied the molecular spectra in the region of the SW streamer, the brightest CO streamer in NGC 253. We constrained the optical depth of the CO emission with the CO/13CO(1–0) ratio, the dense gas fraction with the HCN/CO(1–0), H13CN/13CO(1–0) and N2H+/13CO(1–0) ratios, as well as the shock strength with the SiO(2–1)/13CO(1–0) and CH3OH(2k–1k)/13CO(1–0) ratios. Results. The CO/13CO(1–0) integrated intensity ratio is ∼21 in the SW streamer region, which approximates the C/13C isotopic abundance ratio. The higher integrated intensity ratio compared to the disk can be attributed to the optically thinner environment of CO(1–0) emission inside the SW streamer. The HCN/CO(1–0) and SiO(2–1)/13CO(1–0) integrated intensity ratios both approach ∼0.2 in three giant molecular clouds (GMCs) at the base of the outflow streamers, which implies a higher dense gas fraction and strength of fast shocks in those GMCs than in the disk, while the HCN/CO(1–0) integrated intensity ratio is moderate in the SW streamer region. The contours of those two integrated intensity ratios are extended in the directions of outflow streamers, which connect the enhanced dense gas fraction and shock strength with molecular outflow. Moreover, the molecular gas with an enhanced dense gas fraction and shock strength located at the base of the SW streamer shares the same velocity as the outflow. Conclusions. The enhanced dense gas fraction and shock strength at the base of the outflow streamers suggest that star formation inside the GMCs can trigger shocks and further drive the molecular outflow. The increased CO/13CO(1–0) integrated intensity ratio coupled with the moderate HCN/CO(1–0) integrated intensity ratio in the SW streamer region are consistent with the picture that the gas velocity gradient inside the streamer may decrease the optical depth of CO(1–0) emission, as well as the dense gas fraction in the extended streamer region.

Study of the HCCNC and HNCCC isotopologs in TMC-1

We present the detection of the three 13C isotopologs of HCCNC and HNCCC toward TMC-1 using the QUIJOTE line survey. In addition, the D species has also been detected for these two isomers of HCCCN, whereas the 15N isotopolog was only detected for HCCNC. Using high-J lines of HCCNC and HNCCC, we were able to derive very precise rotational temperatures, column densities, and subsequently the isotopic abundance ratios. We found that 12C/13C is ∼90 for the three possible substitutions in both isomers. These results are slightly different from what has been found for the most abundant isomer HCCCN, for which abundances of 105, 95, and 66 were found for each one of the three possible positions of 13C. The H/D abundance ratio was found to be 31 ± 4 for HCCNC and of 53 ± 6 for HNCCC. The latter is similar to the H/D abundance ratio derived for HCCCN (∼59). The 14N/15N isotopic abundance ratio in HCCNC is 243 ± 24.

Screening of organophosphorus flame retardant residues in rice by QuEChERS-gas chromatography-quadrupole time-of-flight mass spectrometry

Organophosphorus flame retardants (OPFRs) have emerged as good alternatives to brominated flame retardants, the use of which is globally restricted. In this study, a screening method based on QuEChERS-gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) was established for the determination of 21 OPFRs in rice. First, full scan (scanning range, m/z 50-450) was performed with a mixed standard solution of the 21 OPFRs (0.1 μg/g) by GC-Q-TOF/MS. The fragmentation pathways of these OPFRs were then investigated to explore their cleavage fragments, the interrelationships among fragments, and the possible cleavage modes of alkylated, chlorinated, and aromatic OPFRs. The retention times, isotopic abundance ratios, and molecular formulas of the characteristic fragments as well as the exact mass of the compounds were obtained to establish a mass spectral library of the OPFRs. Rice samples were extracted and purified by the QuEChERS method, and 0.5% formate acetonitrile solution was used as the extraction solvent; 4 g of magnesium sulfate, 1 g of sodium chloride, 0.5 g of disodium hydrogen citrate, and 1 g of sodium citrate as the extraction-salt combination; and 50 mg of primary secondary amine (PSA), 50 mg of octadecylsilane (C18), and 150 mg of magnesium sulfate as the purification materials. The chromatographic separation of the 21 OPFRs was completed within 16 min under optimized temperature program conditions on the DB-5MS UI column. The screening parameters were optimized, and a full scan of the samples was performed under the following conditions: number of characteristic fragment ions ≥2; accurate mass window=±2×10-5 (±20 ppm); retention time deviation=±0.2 min, and ion abundance deviation<20%. The developed method was applied to the screening 21 OPFRs in the samples. The results indicated that the matrix interference was greatly reduced by decreasing the extraction accurate mass window, thereby improving the signal-to-noise ratio of the analytes. The targets were extracted from the matrix interference and background noise using deconvolution software, which improved the match between the target compounds and the mass spectral library. The detection rates of alkyl and aromatic OPFRs increased by 22% and 25%, respectively, when the spiking level was increased from 2 to 10 ng/g. Among the chlorinated OPFRs, only tris(2-chloroisopropyl) phosphate (TCIPP) was not detected at a spiking level of 2 ng/g, indicating that chlorinated OPFRs could be identified even at low concentrations. The characteristic ions of the detected compounds matched those of the home-made mass spectral library well, indicating that the practical application of the home-made mass spectral library. The established screening method was applied in the determination of OPFRs in rice samples from different regions in China. A total of 11 OPFRs were detected, among which trimethyl phosphate (TMP), tri-iso-butyl phosphate (TiBP), and tris(3,5-dimethylphenyl) phosphate (T35DMPP) had the highest detection rates. These results indicate that these three OPFRs are widely used and can easily come into contact with rice samples through various routes. Differences in the types of OPFRs detected in the actual samples may be related to the types of OPFRs produced in local factories. OPFRs can be detected in rice samples by the developed GC-Q-TOF/MS screening method, which is helpful for the identification of OPFRs in complex matrix samples.

The complex stellar system M 22: constraining the chemical enrichment from AGB stars using magnesium isotope ratios

ABSTRACT The complex star cluster M 22 (NGC 6656) provides a unique opportunity for studying the slow neutron capture (s-)process nucleosynthesis at low metallicity due to its two stellar groups with distinct iron-peak and neutron capture element abundances. Previous studies attribute these abundance differences to pollution from $3-6 \ \rm {M}_{\odot }$ asymptotic giant branch (AGB) stars which produce significant quantities of the neutron-rich Mg isotopes 25Mg and 26Mg. We report the first-ever measurements of Mg isotopic abundance ratios at $\rm {[Fe/H]} \ \sim -2$ in a globular cluster-like system using very high-resolution and signal-to-noise spectra (R = 110 000, S/N = 300 per pixel at 514 nm) from the VLT/UVES spectrograph for six stars; three in each s-process group. Despite the presence of star-to-star variations in 24Mg, 25Mg, and 26Mg, we find no correlation with heavy element abundances, implying that the nucleosynthetic source of s-process enrichment must not influence Mg isotope ratios. Instead, a key result of this work is that we identify correlations between 26Mg/24Mg and some light elements. Using a custom suite of AGB nucleosynthesis yields tailored to the metallicity of M 22, we find that low mass ($\sim 1 \rm {-} 3 \ \rm {M}_{\odot }$) AGB stars are capable of reproducing the observed s-process abundances of M 22 and that the absence of any difference in Mg isotope ratios between the two s-process groups precludes AGBs with masses above $\sim 3 \ \rm {M}_{\odot }$. This places tighter constraints on possible formation scenarios and suggests an age difference of at least $\sim 280 \rm {-} 480 \ \rm {Myr}$ between the two populations which is independent of isochrone fitting.

Combined model for 15N, 13C, and spin-state chemistry in molecular clouds

We present a new gas-grain chemical model for the combined isotopic fractionation of carbon and nitrogen in molecular clouds. To this end, we have developed gas-phase and grain-surface chemical networks where the isotope chemistry of carbon and nitrogen is coupled with a time-dependent description of spin-state chemistry, which is important for nitrogen chemistry at low temperatures. We updated the rate coefficients of some isotopic exchange reactions considered previously in the literature, and here we present a set of new exchange reactions involving molecules substituted in 13C and 15N simultaneously. We applied the model to a series of zero-dimensional simulations representing a set of physical conditions across a prototypical prestellar core, exploring the deviations of the isotopic abundance ratios in the various molecules from the elemental isotopic ratios as a function of physical conditions and time. We find that the 12C/13C ratio can deviate from the elemental ratio to a high factor depending on the molecule, and that there are highly time-dependent variations in the ratios. The HCN/H13CN ratio, for example, can obtain values of less than ten depending on the simulation time. The 14N/15N ratios tend to remain close to the assumed elemental ratio within approximately 10%, with no clearly discernible trends for the various species as a function of the physical conditions. Abundance ratios between 13C-containing molecules and 13C+15N-containing molecules however show somewhat increased levels of fractionation as a result of the newly included exchange reactions, though they still remain within a few tens of percent of the elemental 14N/15N ratio. Our results imply the existence of gradients in isotopic abundance ratios across prestellar cores, suggesting that detailed simulations are required to interpret observations of isotopically substituted molecules correctly, especially given that the various isotopic forms of a given molecule do not necessarily trace the same gas layers.

Propagation and variation of material characteristics during the uranium ore concentrate production at Dolní Rožinka, Czech Republic

In the framework of the European Commission Support Programme to the International Atomic Energy Agency (EC SP task A1753) 20 samples were obtained from the Dolní Rožínka (DIAMO, Czech Republic) uranium milling facility. The sampling procedure followed stepwise the uranium production and purification from the U ore to uranium ore concentrate (yellow cake) end-product. Elemental concentrations, rare-earth elemental pattern, anion concentrations, morphology and isotope abundance ratios of S, Sr, Pb and U were measured at each sampling stage. The purpose of the measurements was to investigate the applicability of various material characteristics for authentication, propagation and variation of these parameters, and to identify the relevant signatures for nuclear forensics and safeguards during the uranium production.

Direct measurements of carbon and sulfur isotope ratios in the Milky Way

Context. Isotope abundance ratios provide a powerful tool for tracing stellar nucleosynthesis, evaluating the composition of stellar ejecta, and constraining the chemical evolution of the Milky Way. Aims. We aim to measure the 12C/13C, 32S/34S, 32S/33S, 32S/36S, 34S/33S, 34S/36S, and 33S/36S isotope ratios across the Milky Way. Methods. With the IRAM 30 meter telescope, we performed observations of the J = 2−1 transitions of CS, C33S, C34S, C36S, 13CS, 13C33S, and 13C34S as well as the J = 3−2 transitions of C33S, C34S, C36S, and 13CS toward a large sample of 110 high-mass star-forming regions. Results. We measured the 12C/13C, 32S/34S, 32S/33S, 32S/36S, 34S/33S, 34S/36S, and 33S/36S abundance ratios with rare isotopologs of CS, thus avoiding significant saturation effects. With accurate distances obtained from parallax data, we confirm previously identified 12C/13C and 32S/34S gradients as a function of galactocentric distance. In the central molecular zone, 12C/13C ratios are higher than suggested by a linear fit to the disk values as a function of galactocentric radius. While 32S/34S ratios near the Galactic center and in the inner disk are similar, this is not the case for 12C/13C, when comparing central values with those near galactocentric radii of 5 kpc. As was already known, there is no 34S/33S gradient but the average ratio of 4.35 ± 0.44 derived from the J = 2−1 transition lines of C34S and C33S is well below previously reported values. A comparison between solar and local interstellar 32S/34S and 34S/33S ratios suggests that the Solar System may have been formed from gas with a particularly high 34S abundance. For the first time, we report positive gradients of 32S/33S, 34S/36S, 33S/36S, and 32S/36S in our Galaxy. The predicted 12C/13C ratios from the latest Galactic chemical-evolution models are in good agreement with our results. While 32S/34S and 32S/36S ratios show larger differences at larger galactocentric distances, 32S/33S ratios show an offset across the entire inner 12 kpc of the Milky Way.

Noble gas isotopic compositions and abundance ratios of mantle xenoliths from Honolulu series volcanism, Oahu, Hawaii

We report new noble gas isotopic compositions and abundance ratios (helium, neon, and argon) extracted from six lherzolite xenoliths on Oahu Island, Hawaii, by vacuum crushing. Considering the equilibrium temperature of the xenoliths and the fluid density of their fluid inclusions, they originated from a pressure of 0.98–1.04 GPa, corresponding to 33–34 km depth. The Moho depth beneath Oahu Island is around 15 km, suggesting that the xenoliths are part of the sub-oceanic lithospheric mantle (SOLM), 90 million years old, after generation of mid-oceanic ridge basalts (MORB). The samples have 3He/4He of 3.0–9.5 times atmosphere (Ra). The neon isotope compositions overlap with the data of previous studies for lava flow samples of the Hawaiian Islands, MORB, and air. The 40Ar/36Ar range from atmospheric to 3100. They show very low 4He/40Ar* and 4He/21Ne*, where asterisks denote correction for atmospheric contributions. The low 4He/40Ar* and 4He/21Ne* are characteristic of small fluid inclusions, based on step crushing experiments, indicating that they record kinetic fractionation that occurred in the SOLM most likely due to melt infiltration. Using 4He/40Ar* and 20Ne/22Ne respectively as indices of the kinetic fractionation and atmospheric contribution, we corrected for these effects. The corrected noble gas isotopic compositions are best explained by interaction between plume-derived melts and SOLM. The kinetic fractionation yields a decrease in 3He/238U in SOLM, which should result in a rapid decrease in 3He/4He with time. The slightly elevated 3He/4He (above 8 times atmospheric), as found in the present xenoliths cannot be maintained for more than one million years in the fractionated SOLM with 3He/U molar ratio of ∼1 × 10−8, which is calculated assuming that the 3He/U has the same degree of kinetic fractionation as 4He/40Ar* and 4He/21Ne*. Therefore, the fractionation event is likely to be recent, and may be related to recent magmatism in the SOLM beneath Oahu Island. Such igneous activity is limited to Honolulu series volcanism (0.35–0.80 Ma). Therefore, the xenoliths contain a record of magmas with plume-derived noble gases, most likely associated with the Honolulu series volcanism.

Elimination of spectral interference of 87Rb with 87Sr during ICP-MS measurements using a chromatographic technique.

A new chromatographic separation technique was developed for the measurement of the strontium (Sr) isotope abundance ratio using inductively coupled plasma mass spectrometry (ICP-MS). This technique, LC-ICP-MS, utilizes the addition of 18-crown-the eluent and an ODS column. The technique completely eliminates the spectral interference of 87Rb (an isobar of 87Sr) with 87Sr during the ICP-MS measurement. 18-Crown-6 selectively forms a clathrate compound with some metals. When the Sr isotope abundances are measured using LC-ICP-MS with an ODS column, the addition of a specific amount of 18-crown-6 to the HNO3/0.1% methanol eluent elongates the retention time of Rb. Therefore, Rb can be completely separated from Sr using LC because Rb is captured into the 18-crown-6 molecule and forms a clathrate compound. The technique enables the measurement of Sr isotope abundance ratios easily, even in the presence of a large amount of Rb. The proposed technique was applied to the measurement of Sr isotope abundance ratios in rice samples. To validate the LC-ICP-MS technique, a fraction containing Sr was collected, and the 87Sr/86Sr isotope ratio was precisely measured using ICP-MS.

Metasomatized mantle lithosphere and altered ocean crust as a fluid source for orogenic gold deposits

Whether auriferous hydrothermal fluid is generated during crustal metamorphism or by subcrustal processes to form orogenic gold deposits is hotly debated. Noble gas isotope and halogen abundance ratios can provide important constraints to help resolve this controversy. The Danba gold deposit is a rare example of a Jurassic age hypozonal orogenic gold deposit on the western margin of the Yangtze Craton, China. It is characterized by thick barren quartz veins with fractures infilled by thin auriferous quartz veinlets. The syn-gold quartz veinlets are associated with plagioclase and pyrrhotite and are distinguished from the barren quartz vein hosts on the basis of cathodoluminescence, trace-element content and Raman spectroscopy and microthermometry of fluid inclusions. The dominant fluid inclusions in the gold-bearing quartz and plagioclase are H2O–CH4 with vapor fill of ∼ 15–45 vol% and high pressure-corrected trapping temperatures of ∼ 500 °C, low salinities (<4 wt% NaCl equiv.) and high Mg/Fe ratios. Crushing syn-gold quartz and plagioclase released fluid inclusions with 40Ar/36Ar ratios of between 490 and 710, molar Br/Cl ratios of (0.3–0.7) × 10−3 and molar I/Cl ratios of (18–60) × 10−6. Crushing syn-gold pyrrhotite released fluid inclusions with 3He/4He ratios of 0.21–0.38 Ra (Ra = air value, 1.39 × 10−6) that are higher than typical crustal values of < 0.1 Ra, and 40Ar/36Ar of 330–640 that are similar to the gold-related quartz-hosted inclusions. The combined noble gas and halogen data do not favor an auriferous fluid derived from K- and U-rich Proterozoic granitic basement, which is expected to have radiogenic 40Ar/36Ar and 3He/4He ratios. Instead, the data are more consistent with a fluid source from underlying mantle lithosphere containing a high proportion of altered ocean crust (AOC). The auriferous fluid that formed the Danba gold deposit is thus considered to have been derived from a source comprising both metasomatized mantle lithosphere that had been fertilized in a Neoproterozoic subduction event and a portion of relict AOC beneath the western margin of the Yangtze Craton. In contrast with syn-gold fluid inclusions, those in pre-gold barren quartz are H2O–CO2 dominated. Crushing pre-gold quartz released fluid inclusions with 40Ar/36Ar ratios of 2410–5450, Br/Cl ratios of (1.2–1.5) × 10−3 and I/Cl ratios of (60–80) × 10−6 that are distinctly different to the gold-ore stage. The higher 40Ar/36Ar ratios of the pre-gold fluids are consistent with a source for the barren host quartz veins from prograde greenschist- to amphibolite-facies metamorphism of the Proterozoic granitic basement.

Ultra-high performance liquid chromatography-orbitrap high-resolution mass spectrometry for rapid screening and identification of 32 illegally added drugs in slimming and anti-impotence health foods

建立了基于超高效液相色谱-Orbitrap高分辨质谱的快速筛查及确证减肥和壮阳类保健食品中32种非法添加药物的分析方法,并总结了数据库建立和应用的相关要点。研究对象聚焦于非法添加药物的衍生物,在对比正负离子模式下各化合物响应强度的基础上建立了高分辨质谱信息库,对提取溶剂、色谱柱温度等实验条件进行了详细探究,尽可能给出了较宽的标准曲线线性范围。使用Hypersil gold vanquish色谱柱(100 mm×2.1 mm, 1.9 μm),梯度洗脱,流量0.3 mL/min,正、负离子全扫描/数据依赖的二级扫描模式,在17 min内完成32种目标化合物的数据采集,通过TraceFinder软件进行快速定性筛查和定量。结果显示在17 min内32种化合物能得到较好分离;2种基质加标溶液中32种化合物的一级质谱离子精确质量数的实测值与理论值均在5×10-6误差之内,二级碎片离子质量数的实测值与理论值均在1×10-5误差之内;方法学验证结果表明,所有化合物均显示出优异的线性关系,相关系数(r2)均大于0.99;固体基质中除达泊西汀、羟基硫代豪莫西地那非、硫代豪莫西地那非、硫代西地那非、去甲基硫代西地那非的回收率较低外,其余27种化合物的回收率为50.5%~84.5%,相对标准偏差(RSD)为1.2%~13%,液体基质中32种化合物的回收率范围为60.4%~109.3%, RSD为0.77%~8.2%;在48份减肥及壮阳类保健食品中检出1份阳性样品,检出率2.08%。该方法操作简单,结果定性准确,可用于减肥及壮阳类保健食品中32种非法添加药物的快速筛查及确证。

Fast screening and confirmation of 73 common prohibited compounds in cosmetics by ultra performance liquid chromatography-quadrupole-time-of-flight high resolution mass spectrometry

建立了超高效液相色谱-四极杆-飞行时间高分辨质谱(UPLC-Q-TOF HRMS)同时快速筛查确证化妆品中73种常见禁用物质的方法。样品经饱和氯化钠溶液分散均匀后,采用含0.2%甲酸的乙腈溶液超声提取,50 mg PSA净化,以8000 r/min高速冷冻离心除脂,采用Waters Acquity HSS T3色谱柱(100 mm×2.1 mm, 1.8 μm)分离。采用多反应监测高分辨扫描模式(MRM HR),以保留时间、一级母离子精确质量数、同位素丰度比和二级子离子精确质量数实现化妆品中73种禁用物质的快速筛查和确证,基质匹配外标法定量。实验比较了不同提取溶剂、净化吸附剂、色谱条件和质谱扫描模式对73种禁用物质测定的影响,并考察了膏霜剂和水剂的基质效应。结果表明,73种禁用物质线性关系良好,相关系数(R2)>0.99;检出限为5~150 μg/kg;定量限为15~450 μg/kg;膏霜剂及水剂两种基质在3个加标水平下的回收率为60.3%~130.3%,日内、日间RSD分别为0.8%~10.0%(n=6)和1.1%~15.0%(n=3)。日常风险监测中检出磺胺甲基异噁唑、甲基泼尼松、林可霉素、对乙酰氨基酚、甲氧苄啶、阿法骨化醇、倍他米松戊酸酯、溴莫尼定、氯霉素、氯苯那敏、氯倍他索丙酸酯、克罗米通、益康唑、酮康唑、泼尼松醋酸酯和泼尼松,检出含量范围为0.5~1136.1 mg/kg。该方法准确、快速、简便,可用于化妆品中73种常见禁用物质的检测。

Stellar population astrophysics (SPA) with the TNG

Context. The Perseus complex in the outer disk of the Galaxy hosts a number of clusters and associations of young stars. Gaia is providing a detailed characterization of their kinematic structure and evolutionary properties. Aims. Within the SPA Large Program at the TNG, we secured HARPS-N and GIANO-B high-resolution optical and near-infrared (NIR) spectra of the young red supergiant (RSG) stars in the Perseus complex in order to obtain accurate radial velocities, stellar parameters, and detailed chemical abundances. Methods. We used spectral synthesis to best fit hundreds of atomic and molecular lines in the spectra of the observed 27 RSGs. We obtained accurate estimates of the stellar temperature, gravity, micro- and macroturbulence velocities, and chemical abundances for 25 different elements. We also measured the 12C/13C abundance ratio. Results. Our combined optical and NIR chemical study provides homogeneous half-solar iron with a low dispersion, about solar-scaled abundance ratios for the iron-peak, alpha-, and other light elements, and a low enhancement of Na, K, and neutron-capture elements. This is consistent with the thin-disk chemistry traced by older stellar populations at a similar galactocentric distance of about 10 kpc. We inferred an enhancement of N and a depletion of C and of the 12C/13C isotopic abundance ratio that are consistent with mixing processes in the stellar interiors during the RSG evolution.

Supernova Nucleosynthesis, Radioactive Nuclear Reactions and Neutrino-Mass Hierarchy

The ν-process nucleosynthesis in core-collapse supernovae is a sensitive probe of unknown neutrino mass hierarchy through the MSW effect. We carefully studied the uncertainties of almost one hundred ν-induced and nuclear reactions associated with the nucleosynthesis and found that the ν-16O and 11C(α,p)14N reactions among them have the biggest effect on the final 7Li/11B isotopic abundance ratio. The neutrino mass hierarchy is constrained in our nucleosynthetic method with measured 7Li/11B value in SiC-X presolar grains. The inverted hierarchy is statistically more favored at the 2-σ C.L. [1].

The challenging direct measurement of the 65 keV resonance strength of the 17O(p,γ)18F reaction at LUNA

A precise determination of proton capture rates on oxygen is mandatory to predict the abundance ratios of the oxygen isotopes in a stellar environment where hydrogen burning is active. The 17O(p,γ)18F reaction, specifically, plays a crucial role in AGB nucleosynthesis as well as in explosive hydrogen burning occurring in type Ia novae. At temperatures of interest for the former scenario (20 MK ≤ T ≤ 80 MK) the main contribution to the astrophysical reaction rate comes from the Ec.m. = 65 keV resonance. The strength of this resonance is presently determined only through indirect measurements, with an adopted value of ωγ = (1.6 ± 0.3) × 10−11 eV. Thanks to the low background environment of the Laboratori Nazionali del Gran Sasso, the intense and stable beam provided by the LUNA 400 kV accelerator and the experience in oxygen target production, the LUNA collaboration is aiming the first direct measurement of the above mentioned resonance strength. In the present work details of challenging direct measurement planned at LUNA will be described.

Characterization of Ephedrine as Illegal Methamphetamine Precursors Based on δ15N, δ13C, and δ2H Isotopes: Their Application for Methamphetamine Profiling in Indonesia

Objectives: The δ15N, δ13C, and δ2H profile of the ephedrine as a methamphetamine precursor is a fingerprint to describing its origin. The origin of the precursor is one of the supporting data in methamphetamine profiling. In this research, the isotope profiles of natural, synthetic, and semi-synthetic clusters of ephedrine were established. These clusters were applied to predict the origin ephedrine from seized methamphetamine samples in Indonesia. Methods: The isotope profiles of methamphetamine and its precursor were clustered in two steps. Initially, ephedrine and pseudoephedrine from various of the origin were prepared, and then the methamphetamines were synthesized from 4 samples ephedrine of known origin using Emde and Moscow routes. Emde is a method mostly found in Indonesia, and also Moscow as a comparison. Elemental Analyzer-IRMS were used to analyze isotope abundance ratio in order to establish the natural, synthetic, and semi-synthetic clusters. This study was carried out to a total of 20 methamphetamine samples to identified the origin of precursors. Results: The results showed that the isotope profiles of ephedrine and pseudoephedrine formed groups based on the origin. And the isotope profiles of methamphetamine were similar to those of the precursors. Conclusion: The δ15N, δ13C, and δ2H isotope clusters of ephedrine/pseudoephedrine can be applied to seized methamphetamine samples to characterize the origin of the precursor.

The 13CO-rich atmosphere of a young accreting super-Jupiter.

Isotope abundance ratios have an important role in astronomy and planetary sciences, providing insights into the origin and evolution of the Solar System, interstellar chemistry and stellar nucleosynthesis1,2. In contrast to deuterium/hydrogen ratios, carbon isotope ratios are found to be roughly constant (around 89) in the Solar System1,3, but do vary on galactic scales with a 12C/13C isotopologue ratio of around 68 in the current local interstellar medium4-6. In molecular clouds and protoplanetary disks, 12CO/13CO ratios can be altered by ice and gas partitioning7, low-temperature isotopic ion-exchange reactions8 and isotope-selective photodissociation9. Here we report observations of 13CO in the atmosphere of the young, accreting super-Jupiter TYC8998-760-1b, at a statistical significance of more than six sigma. Marginalizing over the planet's atmospheric temperature structure, chemical composition and spectral calibration uncertainties suggests a 12CO/13CO ratio of [Formula: see text](90% confidence), a substantial enrichment in 13C with respect to the terrestrial standard and the local interstellar value. As the current location of TYC8998-760-1b at greater than or equal to160 astronomical units is far beyond the CO snowline, we postulate that it accreted a substantial fraction of its carbon from ices enriched in 13C through fractionation.