Journal of Analytical Chemistry最新文献

Amphibian skin secretion provides the primary defense for frogs against various threats, including predators and pathogens. The composition of this secretion, which is rich in peptides, is unique to each amphibian species and may serve as a taxonomic biomarker, not only for frog species but also for their populations. In this study, we sequenced the components of the skin peptidome of frogs from the Novosibirsk population of Rana arvalis using a range of tandem mass spectrometry techniques, including CID, HCD, ETD, and EThcD. For the first time, we applied an alternative method for collecting secretion in field conditions, which involved manual stimulation to release the secretion. We also evaluated the applicability of the Novor.Cloud program for automatic peptide sequencing in Ranid frogs, focusing on the Novosibirsk population of R. arvalis. The skin peptidomes of the Novosibirsk, Moscow, and Central Slovenian populations of moor frogs were compared. Brevinin 1AVa, brevinin 1AVb, and the melittin-related peptide FQ-22-1, found in the skin secretion of all three populations, may serve as biomarkers for the moor frog, Rana arvalis.

A new approach has been proposed to determining dibenzothiophenes in diesel fuels by HPLC-MS/MS with electrospray ionization. The developed method is based on the preliminary derivatization of the target compounds through their interaction with aliphatic alcohols in the presence of trifluoromethanesulfonic acid, resulting in the formation of fixed-charge derivatives. These derivatives undergo predictable fragmentation processes, involving the elimination of an alkene from the resulting cation, which allows for their detection by selected reaction monitoring. It has been demonstrated that this analytical method provides low limits of detection for the target compounds, making it suitable for analyzing fuels meeting Euro 5 standards.

The isotopic composition of pedogenic carbonates offers valuable insights into the paleoenvironments in which they formed. However, the analysis of these carbonates is complicated by the simultaneous presence of soil organic matter (SOM) alongside inorganic carbon (IC), the removal of which is a labor-intensive process. Previous research into the influence of organic matter on the isotope analysis of carbonates has yielded contradictory results, and some authors attributed the discrepancies to the properties and quantity of the organic matter. Some researchers suggested that sample preparation methods—such as thermal treatment, plasma ashing, the use of chemical reagents to remove organic matter, and the digestion of samples with phosphoric acid—affect the resulting δ¹³C and δ¹⁸O values more than the organic matter itself. There is no consensus about the necessity of removing SOM before the isotope analysis of carbonates. To assess the impact of SOM on the results of the isotope analysis of carbonates from peat soils, we conducted a series of experiments aimed to select the optimal sample preparation procedure for analysis by continuous-flow isotope ratio mass spectrometry. The study involved two horizons of Sapric Drainic Histosol the histic horizon (TE₂), with 41.67% soil organic carbon (SOC) content and a lower degree of decomposition, and the organogenic horizon (TT), with 4.45% SOC content and a higher degree of decomposition. For the δ¹³C analysis, the best results, comparable to those obtained by removing organic matter with H₂O₂, were achieved using 105% H₃PO₄ to decompose air-dried samples from the TT horizon, with an IC/SOC ratio up to 1 : 10. However, applying this approach to samples with an IC/SOC ratio of 1 : 20, or to soil from the TE₂ horizon with a higher SOC content and lower degree of decomposition, led to a significant depletion of ¹³C in the resulting CO₂. The use of 98% H₃PO₄, thermal treatment of samples at 90°C, and substantial reductions in equilibration time also caused deviations in the δ¹³C values towards a lighter isotopic composition. Deviations from the true values of δ¹⁸O were observed in all experiments. The best results were obtained when samples were digested with 105% H₃PO₄ without thermal treatment or the use of chemical reagents, regardless of the initial SOC content or the IC/SOC ratio.

Among the numerous applications of 3D printing technology in chemistry, data visualization is one of the most unusual as people are typically accustomed to the idea that digital data exist in a purely abstract form. Gas chromatography—mass spectrometry (GC-MS) data are unsuitable for 3D printing without preliminary data processing, as neighboring extracted ion chromatograms merge into a single structure. In this work, we developed an R script (https://osf.io/djkyz) to convert a fragment of raw GC-MS data into an STL file suitable for 3D printing. A series of test prints was conducted to determine the optimal profile for mass spectral peaks, as well as the width and height of chromatographic peaks. A GC-MS fragment containing a group of five closely eluting compounds was 3D-printed using a fused deposition modeling technique and served as a tangible model in mass spectrometry classes. Students reported enhanced clarity and a better understanding of the concept of deconvolution after interacting with the 3D-printed models.

To improve the accuracy of determining low (ng/g) concentrations of noble metals (Au, Pd, Pt, Rh, Ru, and Ir) in geological samples, we experimentally assessed mass spectral overlapping due to certain rock components. It was found that the ion exchange separation of the matrix does not eliminate the interferences from Zr, Hf, and Ta oxides, and in some cases, the complete removal of these elements from the test solution is required. An analysis of SRMs SChS-1, SLg-1, TDB-1, OPY-1, and SBC-1 demonstrated that the use of a Ln-resin as an additional sorbent in combination with the subsequent ICP–MS determination in the low and/or medium resolution mode offers promise.

The review describes the current state of research into the analysis of sulfur-containing compounds in crude oils and their refined products by various methods of chromatography and mass spectrometry. However, the absence of universal analysis methods necessitates employing a diverse array of techniques to detect specific groups of sulfur containing compounds (SCCs).

A sample containing microparticles of two different uranium materials with distinct uranium isotopic compositions was analyzed during an international experiment. Mass spectrometric analysis of 25 particles revealed that, within the measurement error, six particles had an isotopic composition consistent with that of the first material, and three particles were consistent with the second material. However, the uranium isotopic composition of the remaining 16 particles did not match either of the known materials. This indicates that the preliminary examination of uranium microparticles by scanning electron microscopy can identify particles carrying information about the isotopic composition of the source materials.

An ion optical analysis of a static mass analyzer, based on a second-order focusing magnetic mirror, was conducted while accounting for aberrations caused by the movement of ions outside the mean plane of the mass analyzer. As part of this study, an optimization algorithm was developed for the four-dimensional acceptance of the mass analyzer at a fixed resolution, formulated within the framework of the inverse problem.

Diarylheptanoids (DAH) are a class of phenolic secondary plant metabolites possessing a wide range of biological activities and pronounced antioxidant properties. This study proposes an original approach to the rapid screening of diarylheptanoids in plant extracts, based on surface-assisted laser desorption/ionization (SALDI) mass spectrometry on target plates with carbon nanocoating and cationization with lithium ions. The test sample was an extract of birch phloem containing centrolobol (CL) and platyphyllonol (PF), the structures of which were confirmed by NMR spectroscopy. The high intensity of diarylheptanoid signals in the resulting mass spectra made it possible to use tandem mass spectrometry for their search and identification. Using the developed approach, four glycosylated derivatives of CL and PF were discovered and tentatively identified in the studied extract, including those containing monosaccharide and disaccharide residues with pentose and hexose sugars.

The results of measurements of ²³⁵U/²³⁸U isotope ratios in microparticles of a reference material performed by Cameca IMS-4f and Cameca IMS 1280-HR mass spectrometers are compared. Twenty-eight particles of various shapes and sizes and also one spherical uranium oxide particle approximately 0.6 μ in size were analyzed by both instruments. These particles were selected based on a preliminary SEM–EDX analysis. The results indicate that the Cameca IMS-1280 HR mass spectrometer can measure uranium isotope ratios with precision up to thousandths of percent, while the Cameca IMS-4f mass spectrometer can measure only up to tenths of percent. For measurements of uranium-235 concentrations at the 0.7% level, the error range for mass spectrometers with a “large” magnet is two orders of magnitude smaller than the errors from mass spectrometers with a “small” magnet, with measurement errors more than ten times lower. Additionally, while mass spectrometers with a small magnet cannot measure minor isotope concentrations at the 5 × 10^–3% level in submicrometer particles, mass spectrometers with a large magnet can achieve this with an error of less than 10%.