European Journal of Mass Spectrometry最新文献

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.

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${}^F$)${}_4$).

Applied sciences have increased focus on omics studies which merge data science with analytical tools. These studies often result in large amounts of data produced and the objective is to generate meaningful interpretations from them. This can sometimes mean combining and integrating different datasets through data fusion techniques. The most strategic course of action when dealing with products of unknown profile is to use exploratory approaches. For omics, this means using untargeted analytical methods and exploratory data analysis techniques. The current study aimed to perform data fusion on untargeted multimodal (negative and positive mode) liquid chromatography-high-resolution mass spectrometry data using multiple factor analysis. The data fusion results were interpreted using agglomerative hierarchical clustering on biplot projections. The study reduced the thousands of spectral signals processed to less than a hundred features (a primary parameter combination of retention time and mass-to-charge ratios, RT_m/z). The correlations between cluster members (samples and features from) were calculated and the top 10% highly correlated features were identified for each cluster. These features were then tentatively identified using secondary parameters (drift time, ion mobility constant and collision cross-section values) from the ion mobility spectra. These ion mobility (secondary) parameters can be used for future studies in wine chemical analysis and added to the growing list of annotated chemical signals in applied sciences.

Introduction: Serum free light chain (FLC) measurements are increasingly prominent for patients with plasma cell disorders (PCDs) in screening, prognostic stratification, and monitoring therapy responses. Objectives: We aimed to develop a sensitive, reliable, and accurate method for diagnosing PCDs that can notably decrease the time and cost of current methods. Methods: Here, we present a novel approach for FLC measurement using immunoenrichment on micro-affinity chromatography in combination with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) detection. In this study, serum free kappa (κ) and free lambda (λ) light chain (LC) levels in the serum of 105 patients were compared between the nephelometric serum FLC quantification and MALDI-TOF MS detection. Results: Cohen's kappa coefficient between the MALDI-TOF MS-based method and the FLC assay revealed an almost perfect agreement in the case of normal (negative) results (κ = 0.92; 95% confidence interval (CI): 0.837 to 0.968) and a good agreement in the case of increased (positive) results (κ = 0.76; 95% CI: 0.608 to 0.870). In Spearman's correlation analysis, the best correlation was found between serum free κ/λ ratios (r = 0.628, 0.496 to 0.732; p <0.0001). Our method showed sensitivity (92.5%) and specificity (76.3%) for discrimination between the κ/λ FLC ratio compared to the serum FLC assay. Conclusion: The proposed method can significantly contribute to diagnosing and monitoring PCDs as it can significantly be time-saving, cost-effective in FLC measurement.

Although showing fascinating chemical properties and reactivity in solution, heavier tetrelylidyne complexes with M≡E triple bonds have not been studied in the gas phase before due to their high sensitivity towards air and moisture. We selected four group 6 germylidyne complexes, [Cp(PMe₃)₂M≡GeAr^Mes] (M = Mo (1-Mo), W (1-W), Ar^Mes = 2,6-dimesitylphenyl) and [Tp'(CO)₂M≡GeAr^Mes] (M = Mo (2-Mo), W (2-W), Tp' = κ³-N,N',N''-hydridotris(3,5-dimethylpyrazolyl) borate), for a mass-spectrometric study. Liquid Injection Field Desorption Ionization (LIFDI) proved to be a well-suited technique to ionize these sensitive compounds as the spectra show the molecular ions as radical cations and only minor traces of fragmentation or degradation products. In addition, Atmospheric Pressure Chemical Ionization (APCI) connected to a high-resolving tandem mass spectrometer allowed us to study the gas-phase fragmentation behaviour of these compounds. The fragmentation patterns not only comprise the expected losses of phosphane or carbonyl ligands, respectively, but also indicate C-H bond activation by the electron-deficient metal centre. An enhanced reactivity of the tungsten species is visible in a preferred methyl abstraction in the phosphane complex 1-W compared to 1-Mo. Although degradation in solution before ionization obviously can destroy the M≡Ge triple bond, the cleavage of the M≡Ge bond upon gas-phase activation is not observed for the Mo species and only as a minor pathway for the W compounds, highlighting the high bonding energy between metal and tetrel.

Electron ionization mass spectrometry (EI-MS) is often used to characterize volatile and thermally stable organometallic complexes relevant for chemical vapor deposition (CVD) processes. However, this method has limitations for thermally unstable and labile organometallic complexes. In this context, EI-MS is not the preferred method of choice for characterizing such compounds. With three different representative organometallic complexes based on the transition metals yttrium, iridium, and silver, relevant as precursors for CVD of different materials, the significance of liquid injection field desorption/ionization mass spectrometry (LIFDI-MS) as an important precursor characterization tool is exemplified. The precursors are not only reactive toward ambient air, but also thermally labile especially in the case of iridium and silver complexes. As a promising alternative, LIFDI-MS is used to overcome the limitations of EI-MS. For the first time, these complexes were successfully analyzed using LIFDI-MS. The comparison between EI-MS and LIFDI-MS highlights that LIFDI-MS is superior for the mass spectrometric analysis of sensitive and labile complexes. In terms of precursor characterization, LIFDI-MS can be fully exploited to gain valuable insights into the decomposition mechanisms and identifying the nuclearity of organometallic precursors used for CVD applications.

We report the synthesis of molybdenum and tungsten bromo dicarbonyl complexes (POCOP^tBu)M^IIBr(CO)₂ (M  =  Mo or W; POCOP^tBu  =  κ³-C₆H₃-1,3-[OP(tBu)₂]₂) supported by an anionic PCP pincer ligand, and the chromium complex (PNP^tBu)Cr⁰(CO)₃ (PNP^tBu  =  2,6-bis(di-tert-butyl-phosphinomethyl)pyridine) bearing a neutral PNP pincer scaffold. The three group six complexes described in this study have been characterized by Liquid Injection Field Desorption Ionization Mass Spectrometry (LIFDI-MS), NMR, and IR spectroscopy. Single crystal X-ray diffraction studies show the Mo^II and W^II complexes adopt a six-coordinate distorted trigonal prismatic geometry, whereas the Cr⁰ complex exhibits a distorted octahedral geometry.

Field desorption (FD) traditionally is an ionization technique in mass spectrometry (MS) that is performed in high vacuum. So far only two studies have explored FD at atmospheric pressure or even superatmospheric pressure, respectively. This work pursues ion desorption from 13-µm activated tungsten emitters at atmospheric pressure. The emitters are positioned in front of the atmospheric pressure interface of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer and the entrance electrode of the interface is set to 3-5 kV with respect to the emitter. Under these conditions positive, and for the first time, negative ion desorption is achieved. In either polarity, atmospheric pressure field desorption (APFD) is robust and spectra are reproducible. Both singly charged positive and negative ions formed by these processes are characterized by accurate mass-based formula assignments and in part by tandem mass spectrometry. The compounds analyzed include the ionic liquids trihexyl(tetradecyl) phosphonium tris(pentafluoroethyl) trifluorophosphate) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, the acidic compounds perfluorononanoic acid and polyethylene glycol diacid, as well as two amino-terminated polypropylene glycols. Some surface mobility on the emitter is prerequisite for ion desorption to occur. While ionic liquids inherently provide this mobility, the desorption of ions from solid analytes requires the assistance of a liquid matrix, e.g. glycerol.