Fourier transform ion cyclotron resonance mass spectrometry in the speciation of high molecular weight sulfur heterocycles in vacuum gas oils of different boiling ranges

The analysis of sulfur aromatics in vacuum gas oils (VGO) distilled from an Iranian light crude oil is discussed. The VGOs were fractionated into three boiling ranges, 390–460, 460–520, and 520–550 °C, and were analyzed using liquid chromatographic separation on a Pd(II)-bonded stationary phase followed by identification with electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). It was possible to detect a large number of thiophenes, including a substantial number of isomers, in the three VGO fractions. Separation on the palladium phase and inclusion of sulfur-selective derivatization makes electrospray ionization of these nonpolar compounds possible. An elemental composition can be assigned to a large number of S₁ compounds without ambiguity in the presence of abundant hydrocarbons. With an increase in boiling temperature, an increase in the size of the aromatic system and the number of side chain carbon atoms was observed. In addition, the masses of higher magnitude shifted toward larger aromatic systems with an increase in boiling range. A comparison of FT-ICR MS and comprehensive gas chromatography is also given. This work is dedicated to Prof. B. Krebs on the occasion of his 70th birthday.     

傅里叶变换离子回旋共振质谱测定复杂表面活性剂组分

利用傅里叶变换离子回旋共振质谱(FT-ICR-MS),分析了两类复杂的离子型表面活性剂样品。实验结果表明：高分辨FT-ICR-MS,可以简单、快速、准确地获得两类化合物的结构信息,利用其高准确度的质量测定数据,计算出复杂样品中各组分的元素组成,鉴定出具体化合物,显示了FT-ICR-MS在分子结构分析和未知物鉴定中的强大能力。     

Study of the fragmentation mechanism of novel functionalized macrocycles by Fourier transform ion cyclotron resonance mass spectrometry

Liquid secondary ion mass spectrometry (L-SIMS) of six new functionalized macrocycles was investigated. All six compounds yielded abundant fragment ions and protonation molecular ions [M + H](+) under L-SIMS conditions. The proposed fragmentation mechanisms were supported by high-resolution accurate mass data from Fourier transform ion cyclotron resonance mass spectrometric and MS(n) experiments on using sustained off-resonance irradiation collision-induced dissociation.     

Determination of Metabolites in the Cerebellum of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Exposed Mice by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin elicits many harmful effects in tissues. Metabolomic changes and the associated pathway alterations caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin in the cerebellum, an area thought to be less affected by environmental alterations, remain unknown. Here, metabolomics was performed to identify endogenous metabolites that were associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin in the cerebellum of 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated mice using Fourier transform ion cyclotron resonance mass spectrometry. Distinct peaks were located in two mass ranges, 210 m/z–420 m/z and 450 m/z–570 m/z. In principal component space, the high-dose group was clearly separated from the control group. Six metabolites associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin dose were identified. The metabolite 1-palmitoyl lysophosphatidic acid increased with increasing doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin, indicating activation of the rat sarcoma pathway. Biosynthesis of the unsaturated fatty acid 18-hydroxyoleate was inhibited upon 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. The decrease in N-arachidonoyl taurine, implies that taurine increased, suggesting inhibition of neuronal signal transmission. A decrease in N-acetyl-aspartyl-glutamate has been associated with injury of the cerebellum through activation of N-methyl-D-aspartic acid receptors. An increase in glycerophosphoinositol suggests damage to blood–brain barrier function, and changes in purine metabolism were observed because inosine increased following 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. These results suggest that 2,3,7,8-tetrachlorodibenzo-p-dioxin activates the rat sarcoma pathway, alters fatty acid biosynthesis and purine metabolism, inhibits neurotransmitter systems, and is harmful to blood–brain barrier function in the cerebellum.     

环糊精对托品烷手性识别的电喷雾傅立叶变换离子回旋共振质谱研究

用电喷雾傅立叶变换离子回旋共振质谱仪分别研究了以α-环糊精、β-环糊精和γ-环糊精作为手性拆分剂对手性托品烷的手性区分效应,实验结果表明β-环糊精具备较α-环糊精和γ-环糊精更强的手性区分能力,β-环糊精和托品烷的二聚体复合物离子的强度随激发能量的变化和托品烷对映体含量值呈现出一定的线性关系.     

GC-MS headspace analysis of the volatile components of soya oil without heating the sample

The analysis of volatile compounds, and particularly of certain hydrocarbons, e.g. pentane, and some aldehydes, e.g. hexanal, has been used to estimate the degree of oxidation of vegetable oil. We have tested a dynamic headspace technique without heating the sample during the purge time of the analysis. Some tests have been performed after heating the sample at 180°C for a specified time before the analysis, to compare the results of analysis with and without heating. The best results were obtained at room temperature.     

Metabolomics approach for determining growth-specific metabolites based on Fourier transform ion cyclotron resonance mass spectrometry

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS) is the best MS technology for obtaining exact mass measurements owing to its great resolution and accuracy, and several outstanding FT-ICR/MS-based metabolomics approaches have been reported. A reliable annotation scheme is needed to deal with direct-infusion FT-ICR/MS metabolic profiling. Correlation analyses can help us not only uncover relations between the ions but also annotate the ions originated from identical metabolites (metabolite derivative ions). In the present study, we propose a procedure for metabolite annotation on direct-infusion FT-ICR/MS by taking into consideration the classification of metabolite-derived ions using correlation analyses. Integrated analysis based on information of isotope relations, fragmentation patterns by MS/MS analysis, co-occurring metabolites, and database searches (KNApSAcK and KEGG) can make it possible to annotate ions as metabolites and estimate cellular conditions based on metabolite composition. A total of 220 detected ions were classified into 174 metabolite derivative groups and 72 ions were assigned to candidate metabolites in the present work. Finally, metabolic profiling has been able to distinguish between the growth stages with the aid of PCA. The constructed model using PLS regression for OD₆₀₀ values as a function of metabolic profiles is very useful for identifying to what degree the ions contribute to the growth stages. Ten phospholipids which largely influence the constructed model are highly abundant in the cells. Our analyses reveal that global modification of those phospholipids occurs as E. coli enters the stationary phase. Thus, the integrated approach involving correlation analyses, metabolic profiling, and database searching is efficient for high-throughput metabolomics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Determination of petroleum sulfonates in crude oil by column-switching anion-exchange chromatography

A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted with the dichloromethane/methanol （60/40）. The high performance liquid chromatography （HPLC） system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.     

Synchronous fluorescence spectroscopy and gas chromatography to determine the effect of UV irradiation on crude oil

The fate of the crude oil under irradiation was studied. After the UV irradiation, the fraction present in the highest percentage shifted from C8–C9 fraction to C13 one, in GC–MS analysis. An increase of the relative amount of the C13–C25 fraction was observed, while a decrease in the relative amount of the C7–C12 fractions was present. The synchronous fluorescence spectrum showed a maximum at 396 nm. Two hours irradiation of the sample induced an increase of the fluorescence emission in the region 420–550 nm. After 20, 40, 60, and 100 h irradiation we observed a decrease of the fluorescence emission.     

Fourier transform ion cyclotron resonance mass spectrometry of covalent adducts of proteins and 4-hydroxy-2-nonenal, a reactive end-product of lipid peroxidation

Covalent adduction of the model protein apomyoglobin by 4-hydroxy-2-nonenal, a reactive end-product of lipid peroxidation, was characterized by nanoelectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FTICR). The high mass resolving power and mass measurement accuracy of the instrument facilitated a detailed compositional analysis of the complex reaction product without the need for deconvolution and transformation to clearly show the pattern of adduction and component molecular weights. Our study has also demonstrated the value of electron capture dissociation over collision-induced dissociation for the tandem mass spectrometric determination of site modification for the 4-hydroxy-2-nonenal adduct of oxidized insulin B chain as an example. Figure FTICR allowed characterization of 4-hydroxy-2-nonenal (HNE)-modified apomyoglobin (an expanded spectrum of the +15 charge state is shown)     

渤海稠油及其组分中杂原子化合物的负离子电喷雾-高分辨质谱分析

采用沉淀法和色谱分离法将渤海某油田稠油分离成沥青质、胶质、剩余分3个组分。采用负离子电喷雾技术(ESI)结合高分辨傅立叶变换离子回旋共振质谱仪(FT-ICRMS)研究了该稠油及各组分的分子组成。结果表明,剩余分中有较少的极性杂原子化合物能被负离子ESI电离,如N1,N1O1,O1和O2类,其等效双键数(DBE)较小。胶质和原油中极性化合物有相同的杂原子类型,包括N1,N1O1,N1O2,N2,N2O2S1,O1,O2,其中胶质和原油中N1,O1,O2类化合物的DBE-碳数分布图相似。沥青质中富集高缩合度且多杂原子的酸性化合物,如含杂原子N,S的氧化程度高的化合物(N2O1,N1O3,S1O3)及O3类化合物,这些物质具有较高的界面活性,易吸附在界面上促进界面张力降低和增强界面膜强度,从而有利于乳状液稳定存在。N1O1,N1O2,N1O3类化合物,N2O1类化合物可能分别是N1化合物,N2化合物的氧化降解产物;随着氧化降解程度增加,降解产物的极性明显增强。     

Isomer separation of hyperbranched polyesteramides with gas-phase H/D exchange and a novel MS(n) approach: DoDIP

Two approaches are introduced that provide information about the isomeric composition of hyperbranched polyesteramides. The first approach is based on a novel tandem mass spectrometric (MS(n)) approach that allows the study of different types of isomeric structures by a separation based on their difference in appearance energy. The method is called DoDIP: dissociation of depleted ion populations. A first MS/MS step is used to fragment isomers with relatively low appearance energy. The isomers with higher appearance energy are fragmented in a second MS/MS step of higher energy. The second approach is based on gas-phase H/D exchange experiments that result in a bimodal isotopic distribution for oligomers X(n)D(n+1) of which one distribution corresponds to a type of isomeric structure that exhibits H/D exchange behaviour and the other to an isomeric structure that does not exhibit H/D exchange behaviour. X is a difunctional anhydride of phthalic acid (P), 1,2-cyclohexanedicarboxylic acid (C), succinic acid (S) or glutaric acid (G). D in X(n)D(n+1) is a trifunctional diisopropanolamine and n the degree of polymerization. The type of isomeric structure that does not exhibit H/D exchange behaviour has a non-alternating monomer sequence that contains an amine bond with a relatively high proton affinity. The other isomeric structure that does exhibit H/D exchange behaviour has an alternating monomer sequence containing only amide and ester bonds with relatively low proton affinity. Oligomer structures were confirmed with additional MS(2) experiments after H/D exchange. H/D exchange experiments on the fragments obtained after MS(2) of the parent ion show that next to previously postulated mechanisms for the cleavage of the ester and amide bond another reaction pathway must be operational. A new mechanism is introduced to explain the H/D exchange behaviour of the fragments that requires a cleavage of the amide bonds only. Two types of fragments are formed by this mechanism. One type is protonated due to the cleavage of the amide bond whereas the other type has an oxazolonium ion structure due to the loss of an additional H(2)O.     

基质与样品的相互作用对于傅立叶变换离子回旋共振质谱测定低分子量多肽的影响

通过比较两种极性差异较大的基质2,5-二羟基苯甲酸(DHB)和2’,6’-二羟基苯乙酮(DHAP)按不同比例混合时,AngiotensinⅡ的基质辅助激光解析电离-傅立叶变换离子回旋共振质谱(MALDI-FT/ICRMS)谱图的不同,并结合基质-AngiotensinⅡ在不同结晶方式下的共结晶和基质晶体的扫描电镜照片,发现基质为10μmol/L DHB和15μmol/L DHAP以体积比4:1组成的混合物时,基质结晶为致密的层状结构,而以薄层法与AngiotensinⅡ生成的共结晶,AngiotensinⅡ在基质晶体上面形成分散的柱状小晶体,此时得到的MALDI-FT/ICRMS质谱图优于干滴法。     

Studies on chemical constituents of Flos Puerariae-Semen Hoveniae medicine pair by HPLC and Fourier transform ion cyclotron resonance mass spectrometry

Alcoholic liver disease is currently the most clinically concerning liver disease, which occurs from chronic alcohol abuse. Flos Puerariae and Semen Hoveniae have been used to treat alcohol drinking excessively for thousands of years in China. In this study, the ethanol extract of the medicine pair was qualitatively and quantitatively analyzed by high-performance liquid chromatography and Fourier transform ion cyclotron resonance mass spectrometry. First, the high-performance liquid chromatography fingerprint was established to obtain the overall chromatographic data of its chemical constituents. Next, high-performance liquid chromatography-mass spectrometry was applied to identify its chemical constituents. Then, the characteristic constituents were simultaneously quantified by high-performance liquid chromatography. In addition, the chemical constituents that were absorbed into rat plasma were identified by high-performance liquid chromatography-mass spectrometry. As a result, a total of 48 chemical constituents in the medicine pair were detected and identified in vitro. Meanwhile, the content of seven representative constituents, including dihydromyricetin, glycitin, genistin, tectoridin, glycitein, genistein, and tectorigenin were simultaneously determined. Furthermore, a total of 19 chemical constituents were detected in rat plasma after oral administration. In short, the chemical constituents of the medicine pair were initially investigated in this study, which will lay the foundation for the discovery of its pharmacodynamic substances in further works.     

Lung alveolar proteomics of bronchoalveolar lavage from a pulmonary alveolar proteinosis patient using high-resolution FTICR mass spectrometry

High-resolution Fourier transform ion cyclotron resonance (FTICR) mass spectrometry was developed and applied to the proteome analysis of bronchoalveolar lavage fluid (BALF) from a patient with pulmonary alveolar proteinosis. With use of 1-D and 2-D gel electrophoresis, surfactant protein A (SP-A) and other surfactant-related lung alveolar proteins were efficiently separated and identified by matrix-assisted laser desorption/ionization FTICR mass spectrometry . Low molecular mass BALF proteins were separated using a gradient 2-D gel. An efficient extraction/precipitation system was developed and used for the enrichment of surfactant proteins. The result of the BALF proteome analysis show the presence of several isoforms of SP-A, in which an N-non-glycosylierte form and several proline hydroxylations were identified. Furthermore, a number of protein spots were found to contain a mixture of proteins unresolved by 2-D gel electrophoresis, illustrating the feasibility of high-resolution mass spectrometry to provide identifications of proteins that remain unseparated in 2-D gels even upon extended pH gradients. Yu Bai and Dmitry Galetskiy both contributed equally to this work.     

Application of FT-ICR-MS for the study of proton-transfer reactions involving biomolecules

Fourier transform ion cyclotron resonance mass spectrometry, combined with modern ionization (fast atom bombardment , electrospray ionization, matrix-assisted laser desorption–ionization), fragmentation (collision-induced dissociation, surface-induced dissociation, one-photon ultraviolet photodissociation, infrared multiphoton dissociation, blackbody infrared radiative dissociation, electron-capture dissociation), and separation (high-performance liquid chromatography, liquid chromatography, capillary electrophoresis) techniques is now becoming one of the most attractive and frequently used instrumental platforms for gas-phase studies of biomolecules such as amino acids, bioamines, peptides, polypeptides, proteins, nucleobases, nucleosides, nucleotides, polynucleotides, nucleic acids, saccharides, polysaccharides, etc. Since it gives the possibilities to trap the ions from a few seconds up to thousands of seconds, it is often applied to study ion/molecule reactions in the gas phase, particularly proton-transfer reactions which provide important information on acid–base properties. These properties determine in part the three-dimensional structure of biomolecules, most of their intramolecular and intermolecular interactions, and consequently their biological activity. They also indicate the form (unionized, zwitterionic, protonated, or deprotonated) which the biomolecule may take in a nonpolar environment. Figure Biomolecules in the gas-phase acidity-basicity scale