Journal of Mass Spectrometry最新文献

Per- and polyfluoroalkyl substance (PFAS) can be present in foodstuff, including preserved foods like canned meats, due to their ubiquity and difficult degradation.

In this work, an analytical method for the quantification of 20 PFAS in canned bovine meat and tuna fish in olive oil was developed, optimized and validated. The analytical approach was based on a QuEChERS extraction, purification with dSPE followed by Solid Phase Extraction (SPE) protocol with subsequent quantification of the extracted analytes by isotope dilution using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry with an Orbitrap analyzer (UHPLC-HRMS). The validation procedure allowed to ascertaining good analytical performances in terms of sensitivity, accuracy and robustness. The values obtained for recovery percentages (range: 80%–120%) were in accordance with the guidelines used for the determination of PFAS in food, LOQs achieved were low enough to ensure compliance with Commission Regulation (EU) 2022/2388 amending Regulation (EC) 1881/2006 as regards maximum levels of perfluoroalkyl substances in certain foodstuffs which was repealed very recently by the Commission Regulation (EU) 2023/915. With the developed method 10 samples from the local markets (n. five canned beef and n. five tuna in olive oil) were analyzed.

Pyranopyrazoles, especially pyrano[2,3-c]pyrazoles, have broad applications as pharmaceutical ingredients and biodegradable agrochemicals, with new compounds and synthesis methods continually emerging. Gas chromatography/mass spectrometry (GC/MS) has difficulty obtaining useful mass spectra under typical measurement conditions due to thermal degradation of the analyte. However, the analysis of the trimethylsilyl (TMS) derivatives of 6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile and 19 closely related analogs provided characteristic ions by which the mass spectral fragmentation pathways could be determined. Nuclear magnetic resonance (NMR) tests showed that the pyran ring cleaved during the TMS derivatization of the compounds with the TMS group connected to oxygen. The fragmentation mechanism involved an alpha cleavage reaction, with the loss of a C₃HN₂ radical to form a stable characteristic cation [M-65]⁺. The mass spectra of positional isomers (o-, m-, and p-) of substituent X (X = Cl, Br, F, CH₃, or OCH₃) on the 4-phenyl group were compared, revealing that the ortho compound has a unique fragment ion peak m/z 261. Lastly, two isomeric di-TMS derivatives were observed: one with both TMS groups connected to nitrogen of the 6-amino substituent (N,N-di-TMS) and the second on the oxygen where the pyran ring was cleaved (N,O-di-TMS). Their mass spectra have apparent differences involving different cleavage pathways.

Development of a rapid, inexpensive, and specific method for chiral amino acids (AAs) identification and separation is challenging owing to their similar properties. In this work, a chiral AAs separation method was developed by analyzing the AAs-cyclodextrin (CD) host–guest complex in the CaptiveSpray-DMS-MS system. Compared with β- and γ-CDs, α-CD was revealed to provide the best differentiation performance. The optimized conditions enabled the analysis of six pairs of respective AA-α-CD complexes within several minutes. Ionograms obtained using this strategy effectively determined the enantiomeric ratio of chiral AAs, as illustrated by the strong linearity (R² = 0.996) between peak abundance ratios and molar ratios of L-serine and D-serine. This method does not require the use of metal ions, and the single peak shape in ionograms of chiral AA-α-CD complex ions simplifies data interpretation.

Quantitative mass spectrometry imaging (QMSI) is being applied for spatial quantification of drugs and metabolites using mass spectrometry imaging (MSI) tools. DESI-MSI is ideally suited to QMSI as a soft and ambient ionization technique. However, some challenging issues of QMSI include extraction efficiency, matrix effect, sensitivity, and specificity, which need to be addressed. Here, we applied targeted DESI-MSI in multiple reaction monitoring (MRM) mode for QMSI of chloroquine, an antimalarial drug, as a model in mice kidneys and carefully addressed those challenging issues. A triple quadrupole mass spectrometer coupled with a DESI source was used to quantify the chloroquine (transition m/z 320.2 → 247.1) drug. A deuterated internal standard chloroquine-d₅ (transition m/z 325.2 → 147.1), was used to normalize the data from pixel to pixel. A mimetic in-tissue model was employed to constract a calibration curve demonstrating good linearity (y = 0.0041x, R² = 0.9953) and precision (RSD < 15%). The calibration curve was validated by back-calculation, with results falling within acceptable ranges (accuracy error< ±15%). Finally, the dosed (30 mg/kg) chloroquine was quantified in three spatial regions (cortex, medulla, and pelvis) in the mice kidneys. The highest concentrations of chloroquine in the pelvis (399.85 and 436.28 ng/mg of kidney tissue at 30 and 60 min intervals) region is consistent with the previous report that a portion of the drug is eliminated from the kidney as unchanged forms. This study provides valuable insights into using DESI-MSI in MRM mode for the QMSI of drugs in biological tissues and will have implications for future research on pharmacology and toxicology.

Ion trap usually serves as a TOF pusher region in ion trap time-of-flight mass spectrometer (IT/TOF), achieving benefits of high duty cycle, MS/MS capability, and high mass resolution. While a short ion trap rod length improves TOF resolution, it limits the mass range in coaxial IT/TOF. Through a computational study based on SIMION simulations, this work systematically investigates the influence of geometric parameters (trap rod length) and voltage parameters (bias DC voltage, end-cap electrode voltage) on the mass range of coaxial IT-TOF systems. By optimizing length of trap rod, over 90% injection efficiency was achieved within a m/z 400–1400 without sacrificing mass resolution. By implementing DC bias voltage adjustments for low-m/z ions and step voltage optimization on end-cap electrodes for high-m/z ions, the simulated mass range is extended to m/z 200–1400 with minimal mass discrimination. All above these findings are derived solely from simulation analysis.

Epimedii Folium (EF) is frequently used in clinical as traditional Chinese medicine with a long history in China. The Pharmacopoeia of the People's Republic of China (2020 Version) contains four species of the plants of the genus Epimedium as its medicinal sources, namely, Epimedium brevicornu Maxim (EBM), E. sagittatum (Sieb. et Zucc) Maxim (ESM), E. pubescens Maxim (EPM), and E. koreanum Nakai (EKN). However, the available studies on a comprehensive analysis of the chemical constituents in the above four species are much scarce. The objective of this study is to establish a method which uses ultra-high performance liquid chromatography coupled with time-of-flight tandem mass spectrometry (UPLC-ZenoTOF-MS/MS) to identify and characterize the chemical constituents in samples from different species. At the same time, multivariate statistical analysis is applied to screen the differential chemical constituents among different species. A total of 116 constituents were identified from different species of EF; and the possible cleavage pathways of various types of constituents were preliminarily inferred based on the fragmentation behavior of the main constituents. Besides, 23 differential characteristic constituents were screened based on variable importance in projection (VIP) value and p-value, of which nine constituents were common differential constituents. The intrinsic quality of EF was thoroughly assessed in this work using metabolomic analysis based on UPLC-ZenoTOF-MS/MS, which provides basic information for the identification of different varieties of EF, and serves as an experimental foundation for the sensible use of EF from various variations in therapeutic practice.