褐煤中有机氮的赋存形态分布和分子结构特征

利用X射线光电子能谱(XPS)分析了先锋褐煤(XL)、小龙潭褐煤(XLT)和胜利褐煤(SL)及其萃取残渣表面有机氮的形态分布。结果表明,三种萃取残渣表面五种有机氮的含量分布各异,但均以吡咯型氮为主。考察了在300℃下Na OH催化的褐煤萃取残渣的超临界甲醇解反应,XL、XLT和SL萃取残渣超临界甲醇解所得石油醚可溶物的收率分别为46.0%、43.8%和47.6%(质量分数)。用傅里叶变换离子回旋共振质谱(FTICR/M S)分析石油醚可溶物中的含氮化合物(NCCs)。结果表明,NCCs主要包括N_1、N_1O_1-N_1O_5、N_2、N_2O_1-N_2O_4、N_3O_2和N_5O_2-N_5O_4类化合物。根据不饱和度和碳原子数的分布推测了NCCs的分子结构特征,表明绝大部分NCCs含羟基和羧基等含氧官能团,氮原子主要以吡咯、吡啶和氨基的形式存在于芳环结构中,以1-3个芳环的结构为主。褐煤中的-C-O-桥键的断裂是生成NCCs的一个重要路径。     

The role of mass spectrometric methods in ionic reaction mechanistic studies

The role of various mass spectrometric methods, including electron ionization, collisional activation, metastable peak shapes, analysis of neutrals from ionic unimolecular dissociations, field ionization kinetics, drift cell, and Fourier transform ion cyclotron resonance spectrometry, in ionic reaction mechanistic studies is described. This is illustrated by selected examples of research performed in the author’s group over the last three decades. They comprise inter alia intramolecular acid–base, anchimeric assistance, nucleophilic attack, isomerization, cycloaddition, S_N2, and hydride ion transfer reactions.     

Liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR MS): an early overview

Fourier-transform ion cyclotron resonance mass spectrometry has developed into one of the most powerful analytical techniques. This unique technique enables acquisition of high-resolution mass spectra with high accuracy, which in turn enables determination of the elemental composition of the analyzed compounds. Coupling with liquid chromatography affords a separation technique with a high-resolution detector which can be used to investigate very complex matrices. In this review some important instrumental developments are described and applications are presented; these show the advantages and disadvantages of this combination.Abbreviations CAD Collision-activated dissociation - CZE Capillary zone electrophoresis - ECD Electron-capture dissociation - FT Fourier-transform - MS Mass spectrometry - ICR Ion cyclotron resonance - IRMPD Infrared multi-photon dissociation - LC Liquid chromatography - LSIMS Liquid secondary-ion mass spectrometry - SORI Sustained off-resonance irradiation This contribution is dedicated to Professor Dr M.T. Reetz on the occasion of his 60th birthday.     

The carbon versus mass diagram to visualize and exploit FTICR‐MS data of natural organic matter

A two‐dimensional diagram is proposed, in which the carbon number of each formula is plotted against its nominal mass, to visualize large sets of molecular formula data that can be derived from data generated by ultrahigh‐resolution Fourier transform ion cyclotron resonance‐MS. In such a carbon versus mass (CvM) diagram, each formula (C_cH_hO_o) is unambiguously described by c, its (nominal) mass and the parameter i = c + o. Calculations of chemically allowable formulas illustrate that organic molecules occupy only certain spaces in such a diagram. The extension of these spaces increases with molecular mass in x‐direction (hydrogenation) and y‐direction (oxygenation). The data sets of molecules determined in natural organic matter(NOM) occupy only a certain range of the allowable space. The intensity of the mass spectrometric signals can be included as the third dimension into a CvM diagram. Separate CvM diagrams can be plotted for NOM molecules that include different heteroatoms. The benefits of the CvM diagram are illustrated by application onto data sets of fulvic acids from riverine and marine origin, of secondary organic aerosol, including organosulfates and organonitrates, as well as of ozonation of fulvic acids. The CvM diagram is a useful tool to visualize the elemental regularities in NOM isolates as well as the differences between isolates. It may also be applicable to large sets of molecular formula data generated in other disciplines such as petroleum biogeochemistry or metabolomics. Copyright © 2010 John Wiley & Sons, Ltd.     

Identification of the metabolites after oral administration of extract of ziziphi spinosae semen to rats or dogs by high‐performance liquid chromatography/linear ion trap FTICR hybrid mass spectrometry

Ziziphi spinosae semen (ZSS) is a traditional Chinese medicine that has been widely used to treat insomnia and anxiety. Modern pharmacological studies have demonstrated that flavonoids are the main active compounds in ZSS. However, the metabolites and the metabolic pathways of flavonoids in ZSS have not been investigated thoroughly. In this study, a method based on high‐performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICR‐MS) was established to identify the metabolites of flavonoids after oral administration of extract of ZSS to rats or dogs, using parent mass list‐triggered data‐dependent multiple‐stage mass analysis at a resolving power of 50,000 in the external calibration mode. The mass accuracies obtained for all full‐scan analyses were less than 4 ppm (<2 ppm in most cases). A total of 15 compounds were detected in biological samples of rats and dogs, and nine compounds were identified. The metabolic pathways of flavonoids of ZSS in rats and dogs were proposed. The results may help better understand the material basis and pharmacological mechanism of ZSS. Copyright © 2012 John Wiley & Sons, Ltd.     

Study by ESI‐FTICRMS and ESI‐FTICRMSn of zinc and cadmium thiophenolate complexes used as precursors for the synthesis of II–VI nanosemiconductors

[M₄(SC₆H₅)₁₀][(CH₃)N]₂, [M₁₀L₄(SC₆H₅)₁₆][(CH₃)N]₄ and [Cd₁₇S₄(SC₆H₅)₂₈][(CH₃)N]₂(M = Cd or Zn, and L = S or Se) zinc and cadmium thiophenolates have been studied by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (ESI‐FTICRMS) and tandem ESI‐FTICRMS (ESI‐FTICRMSⁿ). ESI‐FTICRMS demonstrated its ability to characterize and study such compounds, which may be used as precursors of II–VI nanomaterials. The obtained mass spectrum has been found to be highly relevant of the investigated thiophenolate and the fragmentation behavior of some of the detected ions is indicative of its stability. More specifically, it has been demonstrated that ESI in‐source activation or fragmentation experiments conducted in the Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) cell induced the formation of a very stable entity, which corresponds to the general formula M₄L₄ (M = Zn or Cd and L = S or Se). The elimination of SC₆H₅^? and/or M(SC₆H₅)₂ moieties by various activation processes from the studied thiophenolates led systematically to this structure. Copyright © 2009 John Wiley & Sons, Ltd.     

High mass resolution breath analysis using secondary electrospray ionization mass spectrometry assisted by an ion funnel

In this study, we used secondary electrospray ionization mass spectrometry assisted by an ion funnel (IF) operating at ambient pressure to find compounds in the mass range of 100–500 m/z in online breath fingerprinting experiments. In low‐resolution experiments conducted on an ion trap instrument, we found that pyridine is present in breath of individuals long after drinking coffee. In high‐resolution experiments conducted on a Fourier transform ion cyclotron resonance, we found more than 30 compounds in the mass range of 100–500 m/z in analogous online breath experiments. More than a third of these compounds have molecular weights above 200 Daltons and have not been mentioned in previous studies. In low‐resolution experiments as well as experiments without the IF, these compounds could not be detected. Copyright © 2012 John Wiley & Sons, Ltd.     

Chip‐based nanoelectrospray ionization with Fourier transform mass spectrometric detection to screen for local anesthetics intended to mask limb sore in walking horses

We report a high‐throughput chip‐based nanoelectrospray ionization method coupled with Fourier transform mass spectrometry to screen for local anesthetics in samples collected by swabbing. These drugs have been used to mask pain on the limbs of walking horses after forbidden practices of soring or physical abuse. Optimized for lidocaine, the method afforded sub‐ppm mass accuracy for nine local anesthetics included in the study. From doped cotton swabs, two third and all of the analytes were detected after adding 10 ng and 100 ng of each drug, respectively. Benzocaine and/or lidocaine were found on positive swab samples collected during walking horse competitions. Copyright © 2015 John Wiley & Sons, Ltd.     

N-alkylpyridinium quaternization combined with liquid chromatography–electrospray ionization-tandem mass spectrometry: A highly sensitive method to quantify fatty alcohols in thyroid tissues

A highly sensitive method was developed for the identification and quantification of fatty alcohols in biological tissues. In the presence of pyridine-d₀ and triflic anhydride (Tf₂O), fatty alcohols were converted into permanently charged N-alkylpyridinium ions. Stable isotope-labeled derivatives were generated by pyridine-d₅ and added as internal standard (IS). The mixture was analyzed by liquid chromatography coupled to positive electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS). This method was optimized and validated in terms of reaction time, derivatization efficiency, stability, desalting, and ion suppression effect. Besides, fatty alcohols exhibited good linear relationship (r² > 0.993) over the concentration range of 10 ng mL⁻¹–1 μg mL⁻¹. The limits of detection (LODs) were lowered from previously reported 0.1 ng mL⁻¹ to 0.25 pg mL⁻¹. Precision (RSD% < 15.6%), accuracy (93.0–107.2%), matrix effect, and recovery (in thyroid tissues) were validated as well. Finally, this method was applied for the analysis of ten even carbon-numbered fatty alcohols (C₈–C₂₄) in human thyroid carcinoma and para-carcinoma tissues, revealing a significant decrease of fatty alcohols (free and esterified) in thyroid carcinoma tissues (p < 0.05).     

“Polymeromics”: Mass spectrometry based strategies in polymer science toward complete sequencing approaches: A review

Mass spectrometry (MS) is the most versatile and comprehensive method in “OMICS” sciences (i.e. in proteomics, genomics, metabolomics and lipidomics). The applications of MS and tandem MS (MS/MS or MSⁿ) provide sequence information of the full complement of biological samples in order to understand the importance of the sequences on their precise and specific functions. Nowadays, the control of polymer sequences and their accurate characterization is one of the significant challenges of current polymer science. Therefore, a similar approach can be very beneficial for characterizing and understanding the complex structures of synthetic macromolecules. MS-based strategies allow a relatively precise examination of polymeric structures (e.g. their molar mass distributions, monomer units, side chain substituents, end-group functionalities, and copolymer compositions). Moreover, tandem MS offer accurate structural information from intricate macromolecular structures; however, it produces vast amount of data to interpret. In “OMICS” sciences, the software application to interpret the obtained data has developed satisfyingly (e.g. in proteomics), because it is not possible to handle the amount of data acquired via (tandem) MS studies on the biological samples manually. It can be expected that special software tools will improve the interpretation of (tandem) MS output from the investigations of synthetic polymers as well. Eventually, the MS/MS field will also open up for polymer scientists who are not MS-specialists. In this review, we dissect the overall framework of the MS and MS/MS analysis of synthetic polymers into its key components. We discuss the fundamentals of polymer analyses as well as recent advances in the areas of tandem mass spectrometry, software developments, and the overall future perspectives on the way to polymer sequencing, one of the last Holy Grail in polymer science.