- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Qualitative and Quantitative Distinction of <i>ortho</i> -, <i>meta</i> -, and <i>para</i> -Fluorotoluene by Means of Chirped Femtosecond Laser Ionization
摘要： Femtosecond-laser ionization mass spectrometry (fs-LIMS) is demonstrated to be a powerful analytical method providing access to the qualitative distinction of structural isomers of ortho-, meta-, and para-fluorotoluene. The key point of the approach presented is a systematic variation of the spectral phase of the fs-laser pulses, which characteristically affects the fragmentation pattern observed in the mass spectra. Variation of the linear chirp parameter is also helpful for rationalizing the fragmentation mechanism. Ultimately two ternary mixtures of the three title isomers are quantitatively analyzed in situ with an accuracy of 5% for the molar fractions.
关键词： structural isomers,Femtosecond-laser ionization mass spectrometry,fragmentation pattern,spectral phase,quantitative analysis,fluorotoluene
更新于2025-09-23 15:19:57
-
Localization of metabolites of human kidney tissue with infrared laser-based selected reaction monitoring mass spectrometry imaging and silver-109 nanoparticle-based surface assisted laser desorption/ionization mass spectrometry imaging
摘要： Infrared (IR) Laser Ablation-remote-Electrospray Ionization (LARESI) platform coupled to a tandem mass spectrometer (MS/MS) operated in selected reaction monitoring (SRM) or multiple reaction monitoring (MRM) modes was developed and employed for imaging of target metabolites in human kidney cancer tissue. SRM or MRM modes were employed to avoid artifacts that are present in full scan MS mode. Four tissue samples containing both cancerous and non-cancerous regions, obtained from three patients with renal cell carcinoma (RCC), were imaged. Sixteen endogenous metabolites that were reported in the literature as varying in abundance between cancerous and non-cancerous areas in various human tissues were selected for analysis. Target metabolites comprised ten amino acids, four nucleosides and nucleobases, lactate and vitamin E. For comparison purposes, images of the same metabolites were obtained with ultraviolet (UV) desorption/ionization mass spectrometry imaging (UV-LDI-MSI) using monoisotopic silver-109 nanoparticle-enhanced target (109AgNPET) in full-scan MS mode. The acquired MS images revealed differences in abundances of selected metabolites between cancerous and non-cancerous regions of the kidney tissue. Importantly, the two imaging methods offered similar results. This study demonstrates the applicability of the novel ambient LARESI SRM/MRM MSI method to both investigating and discovering cancer biomarkers in human tissue.
关键词： biomarker,cancer,chemical engineering,mass spectrometry,kidney,imaging,clear cell renal cell carcinoma
更新于2025-09-23 15:19:57
-
Advantages and Limitations of Laser-Assisted Mass Spectrometry for the Local Determination of the Trace Element Composition of Fluid Inclusions in Quarzites in the Bural-Sardyk Deposit (Vostochny Sayan, Buryatia)
摘要： The effect of laser radiation on the surface and volume of natural quartz of the Bural-Sardyk deposit (East Sayan, Buryatia) is studied. The influence of the main parameters of laser radiation with a wavelength of 213 nm (prefix NWR-213) and the properties of the sample on the results of elemental mass spectrometric analysis with inductively coupled plasma are established. The features of laser ablation of various microinclusions in quartz are considered. The main problems arising from the laser evaporation of fluid inclusions in quartzites for the quantitative determination of their chemical composition are indicated.
关键词： superquartzite,fluid inclusions,LA-ICP-MS,inductively coupled plasma mass spectrometry,laser ablation,quartz
更新于2025-09-23 15:19:57
-
Application of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging for Evaluating the Quality of Fish Fillets
摘要： Consumption of fish is rapidly increasing worldwide. It is important to evaluate fish fillet quality because fish undergoes physical and chemical changes during frozen storage. Fish fillets exhibit formaldehyde (FA) accumulation from the decomposition of trimethylamine N-oxide. FA is a powerful protein denaturant; thus, it is important to avoid FA buildup during fish processing to preserve fish quality, especially texture. To determine where FA accumulates, in order to maintain the quality of fish fillets, we performed matrix-assisted laser desorption/ionization mass spectrometry imaging, aiming to identify muscle-derived peptides, which reflect conditions such as denaturation and/or aggregation. We used frozen sections from which lipophilic molecules were washed out and detected various peptide peaks. Furthermore, we tried to identify indices to represent fish fillet softening by protease treatment. We could detect characteristic peaks owing to FA and protease treatment; the findings were consistent with the results of texture profiles showing fish fillet’s real solidity. These molecules might thus serve as effective markers to evaluate fish fillet quality.
关键词： mass spectrometry imaging,peptide,matrix-assisted laser desorption/ionization,protease,formaldehyde
更新于2025-09-23 15:19:57
-
Investigating the Effects of Chemical Gradients on Performance and Reliability within Perovskite Solar Cells with TOF-SIMS
摘要： Time-of-flight secondary-ion mass spectrometry (TOF-SIMS), a powerful analytical technique sensitive to all components of perovskite solar cell (PSC) materials, can differentiate between the various organic species within a PSC absorber or a complete device stack. The ability to probe chemical gradients through the depth of a device (both organic and inorganic), with down to 100 nm lateral resolution, can lead to unique insights into the relationships between chemistry in the absorber bulk, at grain boundaries, and at interfaces as well as how they relate to changes in performance and/or stability. In this review, the technique is described; then, from the literature, several examples of how TOF-SIMS have been used to provide unique insight into PSC absorbers and devices are covered. Finally, the common artifacts that can be introduced if the data are improperly collected, as well as methods to mitigate these artifacts are discussed.
关键词： perovskite solar cells,time-of-flight secondary-ion mass spectrometry,performance,degradation
更新于2025-09-23 15:19:57
-
Subcellular chemical imaging of structurally similar acridine drugs by near-field laser desorption/laser postionization mass spectrometry
摘要： Insights into the pharmacologic effect on cellular processes and the potential toxicological effects are vital to new drug development and evaluation, yet research on these subjects remains a great challenge due to the lack of information regarding the spatiotemporal distribution of drugs and metabolites within a single cell. Mass spectrometry imaging (MSI) has proven to be a label-free and high-throughput approach for visualizing drug distribution in spatial and temporal domains. However, single-cell drug imaging has been limited so far by detection sensitivity and microscale lateral resolution. Herein, we report near-field laser desorption/laser postionization mass spectrometry (NDPI-MS) for single-cell imaging of two structurally similar drugs, proflavine and ethacridine, and subcellular distributions of proflavine at different drug concentrations were investigated. The NDPI-MS imaging results indicate that proflavine was accumulated in lysosomes, which was verified by laser scanning confocal microscopy (LSCM). Additionally, a distinguished subcellular distribution pattern of ethacridine from proflavine could be visualized, highlighting the complexity of the interaction between the drugs and biological environment even though these two drugs possess similar structures. Taken together, the present results demonstrate the great potential of the integrated single-cell MSI platform for characterizing the drug distribution and its phenotype changes within individual cells, expediting the identification and evaluation of newly developed drugs.
关键词： single cell imaging,mass spectrometry,acridine drugs,laser postionization,near-field
更新于2025-09-23 15:19:57
-
A Simple Method for the Evaluation of the Pulse Width of an Ultraviolet Femtosecond Laser Used in Two-Photon Ionization Mass Spectrometry
摘要： A simple method was proposed for on-site evaluation of the pulse width of an ultraviolet femtosecond laser coupled with a mass spectrometer. This technique was based on measurement of a two-photon ionization signal in mass spectrometry by translation of the prism in the pulse compressor of the femtosecond laser. The method was applied to optical pulses that were emitted at wavelengths of 267, 241, and 219 nm; the latter two pulses were generated by four-wave Raman mixing using the third harmonic emission of a Ti:sapphire laser (267 nm) in hydrogen gas. The measurement results show that this approach is useful for evaluation of the pulse width of the ultraviolet femtosecond laser used in mass spectrometry for trace analysis of organic compounds.
关键词： pulse width,mass spectrometry,ultraviolet femtosecond laser,ionization
更新于2025-09-23 15:19:57
-
Impact of Tryptophan Oxidation in Complementarity-Determining Regions of Two Monoclonal Antibodies on Structure-Function Characterized by Hydrogen-Deuterium Exchange Mass Spectrometry and Surface Plasmon Resonance
摘要： Purpose Tryptophan’s (Trp) unique hydrophobic and structural properties make it an important antigen binding motif when positioned in complementarity-determining regions (CDRs) of monoclonal antibodies (mAbs). Oxidation of Trp residues within the CDR can deleteriously impact antigen binding, particularly if the CDR conformation is altered. The goal of this study was to evaluate the conformational and functional impact of Trp oxidation for two mAb subtypes, which is essential in determining the structure-function relationship and establishing appropriate analytical control strategies during protein therapeutics development. Methods Selective Trp oxidation was induced by 2,2′-Azobis(2-amidinopropane) dihydrochloride (AAPH) treatment in the presence of free methionine (Met). The native and chemically oxidized mAbs were characterized by hydrogen-deuterium exchange mass spectrometry (HDX-MS) for conformational changes and surface plasmon resonance (SPR) for antigen-antibody binding. Results Treatment of mAbs with AAPH selectively oxidized solvent accessible Trp residues. Oxidation of Trp within or in proximity of CDRs increased conformational flexibility in variable domains and disrupted antigen binding. Conclusions Trp oxidation in CDRs can adversely impact mAbs’ conformation and antigen binding. Trp oxidation should be carefully evaluated as part of critical quality attribute assessments. Oxidation susceptible Trp should be closely monitored during process development for mAbs to establish appropriate analytical control for manufacturing of drug substance and drug product.
关键词： Tryptophan oxidation,surface plasmon resonance,complementarity-determining region,hydrogen-deuterium exchange mass spectrometry,monoclonal antibody
更新于2025-09-23 15:19:57
-
Neon plasma for effective ionisation of oxygen and fluorine in pulsed glow discharge – high ionisation energy elements quantification in potassium titanyl phosphate single crystals
摘要： Neon glow discharge was tested for the direct analysis of solid dielectric materials by pulsed glow discharge time-of-flight mass spectrometry with an emphasis on the elements with high ionisation energy. The findings for neon were compared to conventional argon glow discharge. Fluorine doped potassium titanyl phosphate (KTP) single crystals were used for analysis. The following parameters were optimised: repelling pulse delay, discharge duration and voltage and pressure in the discharge cell. Relative sensitivity factors were used for quantification; titanium was used for normalisation. Similar to argon glow discharge, the most effective mechanism for fluorine and oxygen ionisation was found to be attributed to high-energy electrons under short repelling pulse delays. Penning ionisation of oxygen in neon glow discharge was found to be less efficient. Overall, the use of neon significantly benefited fluorine and oxygen determination; the limits of detection for oxygen (0.0005 mass %) and fluorine (0.0002 mass %) decreased several times compared to argon glow discharge (0.001 and 0.01 mass %, respectively) as a result of more effective ionisation. The improvement was especially pronounced for fluorine, due to the alleviation of plasma-based interferences. However, for other KTP constituents – potassium, phosphorus and titanium – the analytical performance was expectedly lower, due to the lower sputtering rates in neon glow discharge. The limits of detection for potassium and phosphorus were significantly increased, being 0.008 mass % and 0.01 mass %, respectively. Notably, the performance for non-high ionisation energy elements was adequate for their single-run quantification along with oxygen and fluorine at non-trace levels. Thus, the use of neon as discharge medium for pulsed glow discharge mass spectrometry is clearly justified for the determination of high ionisation energy elements such as oxygen and fluorine in non-conducting matrices.
关键词： oxygen,mass spectrometry,neon,direct determination,fluorine,pulsed glow discharge
更新于2025-09-19 17:15:36
-
Раrаdохical Sесоndаrу Emissiоn Mаss Sресtrum оf thе Lеuсо Fоrm оf Mеthуlеnе Bluе
摘要： A paradoxical relation between the secondary emission mass spectra of Methylene Blue and its leuco form is revealed: in the mass spectrum of the dye cation Cat+ (oxidized form with the molecular weight 284), an intense product of its reduction with m/z 285 is recorded, while the mass spectrum of the leuco dye (reduced form with the molecular weight 285) corresponds to an oxidized form with a dominating peak at m/z 284. An explanation of this empirical fact is proposed: the redox reactions induced by ionizing factors under the conditions of secondary emission experiments pass in the direction permitted for the particular initial form of the redox-active compound. Namely, an oxidized form undergoes reduction, whereas the reduced form is oxidized. This effect should be taken into account for the correct identification of redox-active compounds by their secondary emission mass spectra and for simulating redox reactions in the systems containing redox-active dyes under mass spectrometric conditions.
关键词： leuco form,Methylene Blue cationic dye,secondary emission mass spectrometry,redox reactions
更新于2025-09-19 17:15:36