European Journal of Mass Spectrometry最新文献

Vitamin K is an essential lipophilic vitamin that acts as a coenzyme in several metabolic pathways. Accurate measurement of apolar metabolites transported by lipoproteins in serum matrices requires high-recovery extractions of vitamin K and its derivatives following standardized protocols. Conventionally developed methods in this field have predominantly employed solid-phase extraction for the measurement of vitamin K and its derivatives. In this study, our objective was to develop an enzyme-assisted extraction method for the precise measurement of vitamin K and its derivatives. Our methodology involved mixing 450 µL of serum samples with 50 µL of an internal standard and 50 µL of a lipase enzyme solution. Following vortexing, the mixture was incubated at 37°C for 15 min to activate the enzymes. The enzyme reaction was subsequently quenched with a mixture of 250 µL of methanol and 1 mL of hexane, followed by centrifugation at 12,000 g for 5 min. The upper phase was collected, concentrated using a concentrator device, and dissolved in a 100 µL solution of methanol/acetone/isopropanol (7:1:1, v/v/v) for analysis. Spectrum analysis was performed using the open-source MZmine 3 software, and a reference interval was established using the Python programming language on the Google Colab platform. The developed method for measuring vitamin K and its derivatives exhibited limit of detection and limit of quantitation values of 0.005 and 0.01 ng/mL, respectively. In conclusion, our study presents a precise and reliable method for the measurement of vitamin K and its derivatives using enzyme-assisted extraction.

The objective of this study is to gain insights into the underlying metabolic transformations that occurred during the whole progression of cecal ligation and puncture (CLP)-induced sepsis, thus providing new targets for its treatment. High-performance liquid chromatography of quadrupole time of flight mass spectrometry (HPLC-Q-TOF-MS/MS) combined with multivariate statistical techniques was used to detect the s in serum from septic mice. Fifty male mice were divided into two groups, including the sham group (n = 7) and the CLP-induced sepsis group (n = 43). Animals were sacrificed at 1, 3, 5, and 7 days post-CLP and then serum were collected for metabolomic analysis. Multivariate regression analysis was carried out through MetaboAnalyst 5.0, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), to identify the s and screen out the related differential metabolites. Besides, the KEGG pathway analysis was used to analyze the related metabolic pathways in which the identified metabolites were involved. Based on the fold change (FC > 2.0 or <0.5), variable important in projection (VIP > 1.2), and P value (P < 0.05), we found 26, 17, 21, and 17 metabolites in septic mice at 1, 3, 5, and 7 days post-CLP, respectively, compared with that of the sham group. The PCA and PLS-DA pattern recognition showed a cluster-type distribution between the sham group and the CLP group. Dysregulated amino acid metabolism, as well as disturbed nucleotide metabolism, is observed. Several important metabolic pathways were identified between the sham group and the CLP group. Among them, phenylalanine metabolism, phenylalanine, tyrosine, and tryptophan biosynthesis showed striking at day 1 post-CLP. At day 3, phenylalanine, tyrosine, and tryptophan biosynthesis changed significantly. However, as the disease process, only pyrimidine metabolism showed the most significant alternation, compared to the sham group. Several differential metabolites were identified in the CLP group compared with that of the sham group and they were presented with dynamic alternation at different time points post-CLP, indicating metabolic disturbance occurred throughout the whole sepsis progression.

Bisphenols are known endocrine disruptors commonly utilized in food packaging and storage materials, which frequently come into touch with multiple food products packed in them. The bisphenols in fish feed and other feed materials for aquatic organisms are harmful. The consumption of such marine foods is hazardous. Hence, the feed of aquatic products needs to be verified for the presence of bisphenols. The present study was focused on developing and validating a rapid, selective, and sensitive method to quantify 11 bisphenols from the fish feed with dispersive solid-phase extraction, which was cleaned by an optimized amount of activated carbon spheres and silylated by N,O-bis(trimethylsilyl)trifluoro acetamide and analyzed by gas chromatography-mass spectrometry. The new method was rigorously tested and verified after carefully tuning various parameters affecting analyte recovery. Limit of detection (LOD) were set at 0.5-5 ng/g and limit of quantification (LOQ) at 1-10 ng/g, respectively, resulting in 95-114% recoveries. Interday and intraday precisions in terms of relative standard deviation were found to be less than 11%. The proposed approach was effectively applied in floating and sinking fish feeds. The obtained results showed that higher concentration of bisphenol A, followed by bisphenol TMC, and bisphenol M at a concentration of 256.10, 159.01, and 168.82 ng/g in floating feed and 88.04, 200.79, and 98.03 ng/g in sinking feed samples, respectively.

Edoxaban is an anti-coagulant medication and a director factor Xa inhibitor. A novel reverse phase liquid chromatography-mass spectrometry compatible method developed for separation and identification of new oxidative degradation impurities in edoxaban tosylate hydrate drug substance. The separation of three oxidative degradation impurities was achieved by using YMC Triart phenyl (250  ×  4.6) mm, 5 µm column with mobile phase containing gradient elution of mobile phase-A as 10 mM ammonium acetate and mobile phase-B as acetonitrile:methanol (1:1)% (v/v). The flow rate of the mobile phase is 0.7 mL/min with a column temperature of 40 °C and detection wavelength of 290 nm. Edoxaban tosylate hydrate shows significant degradation in oxidative stress conditions and forms three oxidative degradation products. The degradation products were identified and characterized by using a high-resolution mass spectrometry quadrupole-time of flight mass detector. The three oxidative degradation impurities of Edoxaban drug substance were well resolved with each other and along with Edoxaban drug substance peak. Among the three oxidative degradation impurities di-N-oxide impurity was the new oxidative degradation impurity identified for the first time and a novel reverse-phase high-performance liquid chromatography method was developed for separation of the three oxidative degradation impurities.

Conventional endoscopic biopsy tests are not suitable for early detection of the acute onset and progression of peptic ulcer as well as various gastric complications. This also limits its suitability for widespread population-based screening and consequently, many people with complex gastric phenotypes remain undiagnosed. Here, we demonstrate a new non-invasive methodology for accurate diagnosis and classification of various gastric disorders exploiting a pattern-recognition-based cluster analysis of a breathomics dataset generated from a simple residual gas analyzer-mass spectrometry. The clustering approach recognizes unique breathograms and "breathprints" signatures that clearly reflect the specific gastric condition of an individual person. The method can selectively distinguish the breath of peptic ulcer and other gastric dysfunctions like dyspepsia, gastritis, and gastroesophageal reflux disease patients from the exhaled breath of healthy individuals with high diagnostic sensitivity and specificity. Moreover, the clustering method exhibited a reasonable power to selectively classify the early-stage and high-risk gastric conditions with/without ulceration, thus opening a new non-invasive analytical avenue for early detection, follow-up, and fast population-based robust screening strategy of gastric complications in the real-world clinical domain.

Thermal decomposition of cycloheptane was studied using flash pyrolysis coupled with vacuum ultraviolet (118.2 nm) single photon ionization time-of-flight mass spectrometry at temperatures ranging from 295 K to 1380 K. C-C bond breaking of cycloheptane leading to the 1,7-heptyl diradical was considered as the initiation step. The 1,7-heptyl diradical could readily isomerize to 1-heptene and decompose into several fragments, with dissociation to •C₄H₉ and •C₃H₅ as the predominant product channel. The 1,7-heptyl diradical could undergo direct dissociation, as evidenced by the production of the C₅H₁₀ species. Quantum chemistry calculations at UCCSD(T)/cc-pVDZ//UB3LYP/cc-pVDZ level of theory on the initial reaction pathways of cycloheptane were also carried out to support the experimental observations. Other possible initiation channels, as well as some secondary reaction products, were also identified.

The electron ionisation mass spectra of an extensive set of 53 ionised monosubstituted and disubstituted cinnamamides [XC₆H₄CH=CHCONH₂, X = H, F, Cl, Br, I, CH₃, CH₃O, CF₃, NO₂, CH₃CH₂, (CH₃)₂CH and (CH₃)₃C; and XYC₆H₃CH=CHCONH₂, X = Y = Cl; and X, Y = F, Cl or Br] are reported and discussed. Particular attention is paid to the significance of loss of the substituent, X, from the 2-position, via a rearrangement that is sometimes known as a proximity effect, which has been reported for a range of radical-cations, but is shown in this work to be especially important for ionised cinnamamides. When X is in the 2-position of the aromatic ring, [M - X]⁺ is formed to a far greater extent than [M - H]⁺; in contrast, when X is in the 3-position or 4-position, [M - H]⁺ is generally much more important than [M - X]⁺. Parallel trends are found in the spectra of XYC₆H₃CH=CHCONH₂: the signal for [M - X]⁺ dominates that for [M - Y]⁺ when X is in the 2-position and Y in the 4-position or 5-position, irrespective of the nature of X and Y. Further insight is obtained by studying the competition between expulsion of X^· and alternative fragmentations that may be described as simple cleavages. Loss of ^·NH₂ results in the formation of a substituted cinnamoyl cation, [XC₆H₄CH=CHCO]⁺ or [XYC₆H₃CH=CHCO]⁺; this process competes far less effectively with the proximity effect when X is in the 2-position than when it is in the 3-position or 4-position. Additional information has been obtained by investigating the competition between formation of [M - H]⁺ by the proximity effect and loss of CH₃^· by cleavage of a 4-alkyl group to give a benzylic cation, [R¹R²CC₆H₄CH=CHCONH₂]⁺ (R¹, R² = H, CH₃).

A comparative mass spectrometric investigation using electrospray ionisation (ESI) and liquid injection field desorption/ionisation (LIFDI) techniques is reported for the highly luminescent and cationic copper cluster [(PCP)${}_3$Cu${}_4$]${}^{+}$ (1[Formula: see text], PCP = [1,3-(Ph${}_2$P)${}_2$C${}_6$H${}_3$]${}^{-}$). Depending on the available counter ion X${}^{-}$, ion pairs consisting of the original or a modified cluster cation and the weakly coordinating counter ion can be detected by LIFDI-high-resolution-mass spectrometry in addition to the cluster cation. Notably, only large counter ions with an extremely low tendency for metal coordination give rise to the observation of ion pairs, whereas smaller ions such as BF${}_4^{-}$ do not show peaks corresponding to ion pairs in their mass spectra. In principle, two pathways were identified for the formation of positively charged ion pairs: (i) association of a generated Cu${}^{+}$ ion to the neutral ion pair [(PCP)${}_3$Cu${}_4$]X (1+X, X${}^{-}$ = BAr${}_{20}^F$, BAr${}_{24}^F$) and (ii) abstraction of an electron from the neutral ion pair [(PCP)${}_3$Cu${}_4$]X (1+X), leading to the oxidised ion pair [1+X][Formula: see text] (X${}^{-}$ = Al(OR${}^F$)${}_4$).

Gaussian and exponentially modified Gaussian functions were incorporated into integrating algorithms used by an open-source, cross-platform tool called CycloBranch. The quantitation is demonstrated on bacterial pyoverdines separated by fine isotope features. Using our algorithm, we can separate the m/z values 694.25802 and 694.26731 (a 0.009 Da difference), where the former belongs to the most intense peak of pyoverdine D (PvdD), and the latter to the second most intense peak of pyoverdine E (PvdE) in the respective isotopic clusters of [M + Fe-H]²⁺ ions. The areas under chromatographic curves of standards were analyzed for the limit of detection (LOD), limit of quantitation (LOQ), and regression coefficient calculations. The quantitative module returned a LOD and LOQ of 1.4 and 4.3 ng/mL, respectively, for both PvdD and PvdE in human urine. If present and detected in mass spectra, the intensities of user-defined [M + H]⁺, [M + Na]⁺, [M + K]⁺, [M + Fe-H]²⁺, or other ion types, can be accumulated and used for quantitation. The quantitation result is returned by CycloBranch in seconds or minutes, contrary to an hours-long manual approach, prone to user-born errors originating from necessary copying among various software environments. Native Bruker, Waters, Thermo, txt, mgf, mzML, and mzXML data formats are supported in CycloBranch, which is freely available at https://ms.biomed.cas.cz/cyclobranch.