Journal of Mass Spectrometry最新文献

The results of the mass spectrometric studies of heterogeneous transformations of molecules of psychotropic drugs—piperidine and piperazine derivatives of butyrophenone haloperidol, trifluperidol, droperidol, and azaperone during adsorption on a hot surface of tungsten oxide—have been presented. The relationship between the channels of heterogeneous reactions and the nature of the adsorption centers in the molecules has been established. Ion current lines characteristic of the products of heterogeneous reactions of dehydrogenation, dissociation, and dehydrolysis of molecules with the elimination of up to two water molecules formed during aromatization of amine rings and hydrogen rearrangement with the participation of oxygen of the carbonyl group have been found in the mass spectra. A shift in the maximum yield of heterogeneous reactions towards low emitter–converter temperatures with an increase in the degree of dehydrogenation and dehydrolysis of radicals in the adsorbed layer has been found. At the same time, estimates have shown that within the emitter temperature range from 850 K to 1200 K, the lifetime of radicals in the adsorption layer is reduced from fractions of a second to tens of nanoseconds. At relatively high emitter temperatures (from 800 K), current lines of monomolecular decays of metastable parent ions have been detected. When using the surface of tungsten oxide as a positive ion converter, a high efficiency (up to 98%) of surface ionization of desorbed radicals has been established, making it possible to trace the complete picture of the heterogeneous reactions occurring in the adsorbed layer.

DA-1241 is a novel GPR119 receptor agonist under development as a therapeutic candidate for metabolic dysfunction-associated steatohepatitis. To enable precise quantification of DA-1241 in mouse, rat, dog, and human plasma, a simple and highly sensitive LC-MS/MS approach was designed and thoroughly evaluated. Plasma samples were processed using protein precipitation with acetonitrile, followed by chromatographic separation on a reverse-phase C₁₈ column (3.0-mm i.d. × 50 mm, 2.7 μm). Isocratic elution was achieved using a mobile phase composed of 1-mM ammonium formate and 2-mM formic acid in water and acetonitrile (13:87, v/v) operated at a flow setting of 0.3 mL/min. Mass spectrometry analysis was conducted using an Agilent 6460 triple quadrupole system operated in multiple reaction monitoring with positive electrospray ionization. Ion transitions were m/z 472.1 → 135.9 for DA-1241 and m/z 480.2 → 404.1 for DA-1241-d₈ (internal standard). The total chromatographic run time was 4.5 min. Linearity of the calibration curves was confirmed throughout the range of 1–10 000 ng/mL, with no carry-over observed. Precision and accuracy for intra-assay and interassay were within 14.3%, except at the lower limit of quantification, where values remained within 16.0%. The method met all the other validation criteria for matrix effect, recovery, and stability. The established method was successfully implemented on plasma protein binding assessments and preclinical pharmacokinetic studies of DA-1241 after a single oral administration in mice, rats, and dogs.

A current trend in modern nanotechnology is the combination of inorganic nanomaterials with organic compounds, aiming to obtain nanocomposites whose properties are predetermined by the interactions between their components. In the present investigation, the reflection of noncovalent and covalent interactions in nanocomposites of a promising 2D nanomaterial based on MoS₂ with representatives of biologically significant sulfur-containing organic compounds: amino acid cysteine, tripeptide glutathione, thio-derivative of nitrogen bases thioadenine, and thiol thioglycerol, in the specific features of their laser desorption/ionization (LDI) mass spectra is determined. It turned out that the outcome of the interactions in the composites depended on the type of organic compound. The mutual effect of the nanocomposites' components is revealed in a combined analysis of positive and negative ion LDI mass spectra. MoS₂-catalyzed formation of cysteine, glutathione, and thioadenine oxidation products, being covalent dimers bound by –S–S– disulfide bridge, is documented. Negative ion LDI mass spectra of the nanocomposites contain sets of Mo_xS_yO_z clusters sputtered from the MoS₂ nanosheets, whose patterns differ from those characteristic of pure MoS₂. The general trend is suppression of abundances of clusters with more than one Mo atom, which may be explained by the stabilizing role of organic molecules' adsorption at the surface of MoS₂ flakes. The appearance of naked Mo⁺ ions is observed in the positive ion mode, being most expressed for the composites with thioglycerol and glutathione. The mechanism of Mo⁺ release is proposed: Chemical interactions of thiols with the edges of MoS₂ nanosheets result in the removal of sulfur atoms from the edges, which depletes the molybdenum bonds with the sheet, followed by Mo⁺ splitting off. The observed chemical transformations of sulfur-containing compounds and MoS₂ within the nanocomposites are to be accounted for in the search for applications of their composites.

Local anesthetic compounds may be mixed with counterfeit products and distributed as legitimate pharmaceuticals. In this study, gas chromatography–time-of-flight mass spectrometry (GC–TOF MS) and gas chromatography–triple quadrupole mass spectrometry (GC–QQQ MS) methods are used simultaneously to determine 18 local anesthetics and identify illegal products. First, GC–TOF MS is performed to determine the fragmentation patterns and structures of the 18 compounds and qualitatively screen the samples. GC–QQQ MS is used for quantitative analysis and thoroughly validated for specificity, linearity, limit of detection, limit of quantification, accuracy, precision, and recovery. The samples are divided into liquid, cream, and other forms for testing, with 65.6% (40/61) of samples contaminated with local anesthetics. Lidocaine is frequently identified in the analyzed samples, with a detection range of 0.153–164.0 mg/g. Furthermore, linearity is observed within the concentration ranges of 0.41–1.28, 2.29–2.43, and 1.83–16.3 mg/g for prilocaine, procaine, and tetracaine, respectively. Eugenol is detected in a single sample at 3.45 mg/g. In addition, three components are detected in one sample, adversely affecting human health when used in combination. Therefore, the proposed analytical methods may contribute to the removal of illegal products containing pharmaceutical compounds.

Microsampling techniques such as dried blood spot (DBS) and dried blood matrix (DBM) offer several advantages over venipuncture sampling techniques, including ease of collection, reduced sample volume, improved sample stability and simplified transportation. In this study, mass spectrometry, a highly sensitive analytical instrument capable of handling small sample volumes, was used to compare venipuncture, DBS and DBM sampling methods for the detection of haemoglobin variants—HbS, HbE and HbD-Punjab—and thalassemia in adults. Anonymised leftover K2-EDTA venipuncture blood samples were used, including 10 samples each of normal, HbS trait/disease, HbE trait, HbD trait and α-thalassemia (HbH), as well as eight samples of β-thalassemia. Three biomarker ratios—S/β for HbS, α/β for α-thalassemia (HbH) and δ/β (%) for β-thalassemia—were analyzed. All the sampling techniques successfully distinguished sickle cell trait from sickle cell disease, β-thalassemia trait from β-thalassemia major and detected HbE and HbD-Punjab traits. There were no statistically significant differences between sampling techniques in the qualitative detection of HbS and HbD-Punjab variants. However, HbE variant, α/β and δ/β (%) values were altered in DBS and DBM when compared with venipuncture blood. Statistical evaluation necessitates the need for matrix-matched reference ranges for quantitative thalassemia analysis. Triple quadrupole mass spectrometry provides a unified platform for analysing blood samples using diverse sampling techniques, minimising logistical challenges and enabling efficient, accurate high-throughput screening for haemoglobinopathies in clinical, population-wide and resource-limited settings.

Protein function can vary due to changes in primary structure, such as post-translational modification (PTM), truncation, or amino acid replacement, and functional proteomics methods focus on elucidating changes in the function of proteins in biological pathways. Thermal proteome profiling (TPP) is a powerful functional proteomics approach that analyzes the thermal stability of proteins by exposing them to a temperature gradient to facilitate thermal denaturation, followed by analysis of the remaining folded proteins. Current TPP methods, however, utilize bottom-up methods that require protein digestion and can obscure relevant information regarding the structure of the intact proteoform. In this study, we have developed a top-down (TD) TPP approach to study intact proteoform stability as well as a high-throughput data analysis pipeline for label-free quantitative analysis and identification. We benchmarked this platform using two proteoforms of standard proteins, β-lactoglobulin A and β-lactoglobulin B (βLG-A and βLG-B), and found that βLG-A is slightly stabilized compared with βLG-B as a result of two amino acid substitutions. Additionally, we utilized this platform to detect protein thermal stability shifts induced by ligand binding, using carbonic anhydrase and its known inhibitor, acetazolamide. Our results demonstrated that the TD-TPP platform effectively detected the stabilization of a standard protein upon ligand binding. Furthermore, we adapted the TD-TPP platform for high-throughput thermal stability profiling of the intact E. coli proteome, enabling the characterization of intact proteoform-level thermal stability in complex biological samples. We performed thermal profiling of 72 identified proteoforms and 91 proteoform features (e.g., 163 total proteoforms) from intact E. coli lysate, and found that the melting points of these proteoforms correlated well with melting points determined using bottom-up TPP methods. Overall, the TD-TPP platform is capable of profiling thermal stability for standard proteins and intact proteoforms in complex biological samples.

In this study, we present the first comprehensive application of ion mobility mass spectrometry (IMS MS) combined with collision-induced dissociation (CID MS/MS) to the comparative analysis of the gangliosidome in human hippocampal tissue affected by temporal lobe epilepsy and corresponding healthy controls. Using nanoESI IMS MS, we profiled complex ganglioside mixtures extracted from the human hippocampus affected by temporal lobe epilepsy and the normal hippocampus. A total of 217 ions corresponding to 192 distinct ganglioside species were identified in the epileptic tissue, compared with 156 ions assigned to 137 species in the healthy hippocampus. The majority of these species were polysialylated and exhibited extensive structural diversity in both glycan and ceramide moieties, with important modifications including fucosylation, O-acetylation, GalNAc, and CH₃COO⁻ attachments. The gangliosidome associated with epilepsy was found characterized by a higher overall degree of sialylation than previously known, with the exclusive presence of highly sialylated GP, GS, and GO species reported here for the first time in relation to this disease. CID MS/MS experiments enabled the structural elucidation of several biologically relevant species, including O-Ac–GD1b (d18:1/20:2) and GT1b (d18:1/23:0), demonstrating the method's capacity to resolve complex structures and identify specific ganglioside isomers. Significant differences in the expression and modification patterns between pathological and control samples suggest disease-associated remodeling of membrane components. This study not only reveals novel molecular features of epilepsy-related ganglioside alterations but also establishes IMS CID MS/MS as a powerful analytical platform for advancing glycosphingolipidomics and exploring biomolecular signatures in neurological disorders.