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。     

Gas-phase reactions of the bis(η-cyclopentadienyl)methylzirconium cation with imines

The reactions of the bis(η⁵-cyclopentadienyl)methylzirconium cation (1) with four imines have been studied in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry. Reactivity of the bis(η⁵-cyclopentadienyl)methylzirconium cation is governed by the availability of a labile hydrogen in the corresponding imine. The products observed differ from those that might be expected in analogy with earlier work on ketones, aldehydes and alkenes (e.g., zirconocene η³-enolate and η³-allyl complexes): azomethyne/benzylidene species are found instead of enamines; however, the general reaction mechanism resembles that proposed for ketones and alkenes. An elimination reaction leading to final products was shown to be preceded by a fast migratory insertion/deinsertion equilibrium for alkyl-substituted imines. Such an equilibrium is not possible for aryl-substituted imines due to lack of lability of the aryl groups and thus only methane elimination was observed for these imines.     

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.     

Mass-spectrometric analysis of complex volatile and nonvolatile crude oil components: a challenge

Crude oil analysis has long been an inspiration for the development of analytical techniques. Especially mass spectrometry has flourished as a result of the challenge these extremely complex problems offer. Here an overview of different analytical methods is presented that shows different ways to analyze volatile and nonvolatile crude oil components. Focus has been placed on the use of mass spectrometry and especially the new developments that have been introduced using the emerging technique of Fourier transform ion cyclotron resonance mass spectrometry. These studies are examples of how far the development of analytical methods has come for the task of studying such complex problems.     

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.     

Manipulating internal energy of protonated biomolecules in electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

The internal energy of protonated leucine enkephalin has been manipulated in electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry with two newly designed pump-probe experiments. Blackbody infrared radiation was applied to pump an ion population into a well-defined internal energy distribution below the dissociation threshold. Following this pumping stage, the internal energy distribution was probed using on-resonance collisional activation to dissociate the ions. These pump-probe experiments were carried out in two different ways: (a) using on-resonance collisional activation with variable kinetic energies to dissociate the ions at a constant initial ion temperature (determining the precursor ion survival percentage as a function of kinetic energy) and (b) using on-resonance collisional activation with a constant kinetic energy to dissociate the ions at variable initial ion temperatures (to investigate the ion survival yield-initial ion temperature dependence). Using this approach, a detailed study of the effects of the initial ion temperature, the probing kinetic energy and the internal energy loss rate on the effective conversion efficiency of (laboratory-frame) kinetic energy to internal energy was conducted. This conversion efficiency was found to be dependent on the initial ion temperature. Depending on the experimental conditions the conversion efficiency (for collisions with argon) was estimated to be about 4.0 +/- 1.7%, which agrees with that obtained from a theoretical modeling. Finally, the reconstructed curves of the ion survival yield versus the mode of the (final) total internal energy distribution of the activated ion population (after pump and probe events) at different pump-probe conditions reveal the internal energy content of the activated ions.     

Molecular level comparison of water extractives of maple and oak with negative and positive ion ESI FT‐ICR mass spectrometry

Soluble extractives in wood function to protect living trees from destructive agents and also contribute to wood color and fragrance. Some extractive components have biological activities with medical applications. They also play important roles in wood processing and related applications. To increase the knowledge of wood chemistry, maple and oak were extracted by water. Ultraviolet/visible (UV/vis) spectroscopy indicated the presence of a phenolic compound, resorcinol, in maple extractives having higher molecular mass and more aromatic components than oak extractives. Negative and positive electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT‐ICR‐MS) identified thousands of formulas in the two samples in the m/z range of 200 to 800. They mainly fall into the lignin‐like, carbohydrate‐like, and tannin‐like compound categories. The top 25 peaks (ie, formulas) with the highest relative magnitude in negative ESI represented nearly 50% of the summed total spectral magnitude of all formulas assigned in the maple and oak extractives. Furthermore, the base peak (ie, most abundant peak) accounted for about 14% of the total abundance in each wood sample. Literature comparisons identified 17 of 20 formulas in the top five peaks of the four spectra as specific bioactive compounds in trees and other plants, implying the potential to explore utilization of maple and oak extractives for functional and medicinal applications. The various profiling of the top 25 peaks from the two samples also suggested the possible application of FT‐ICR‐MS for detecting chemical markers useful in profiling and identification of wood types and sources.     

傅立叶变换离子回旋共振质谱法测定生物样品中的溶血磷脂酰胆碱

建立了一种快速、同时测定复杂生物样品中4种溶血磷脂酰胆碱(LPCs)的傅立叶变换离子回旋共振质谱(FTICR-MS)分析方法。生物样品以甲醇-氯仿(9∶1,体积比)超声萃取30 min,离心后取上清液过0.22μm滤膜,进行FTICR-MS分析。质谱分析采用250μL微量进样器直接进样,进样流速为120μL/h;电喷雾(ESI)正离子模式检测,扫描质荷比范围为m/z 50～1 000,采用外标法进行定量分析。结果表明,4种LPCs在0.5～100μg/L质量浓度范围内呈良好的线性关系,相关系数(r~2)均不小于0.993 0。4种LPCs的检出限为0.02～0.03μg/L,定量下限为0.07～0.1μg/L。在血液和大鼠肝脏样本中,3个加标水平下4种LPCs的平均回收率为70.8%～95.0%,相对标准偏差(RSD)为1.2%～9.8%。该方法简单快速,灵敏度高,准确性和重复性好,适用于复杂生物样品中LPCs的快速测定。     

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.     

Qualitative and quantitative studies on chemical constituents of Ling-gui-zhu-gan decoction: In vitro and in vivo

Ling-gui-zhu-gan decoction has significant therapeutic effects in the treatment of diseases related to phlegm and fluid retention. In this study, we aimed to qualitatively characterize the chemical constituents of Ling-gui-zhu-gan decoction in vitro and in vivo by HPLC coupled to Fourier transform ion cyclotron resonance MS, and quantitively determine the contents of typical chemical constituents by HPLC method. As a result, a total of 75 chemical constituents were discovered including 37 flavonoids and their glycosides, 20 saponins, 9 sterols, 3 organic acids and their derivatives, 3 lactones, 2 coumarins, and 1 alcohol. Among them, 17 chemical constituents were specifically identified. Subsequently, an HPLC method was established for simultaneous determination of seven chemical constituents. Finally, a total of 40 prototype components were initially detected by HPLC-MS method in the biological samples of rats after their water extract was orally administrated. Among them, 29, 27, 12, and 32 prototype components were detected in plasma, bile, urine, and feces, respectively. Moreover, 34 metabolites, including 16 phase II metabolites, were detected for the first time. In conclusion, this study lays the foundation for the identification of chemical components in vitro and in vivo and the elucidation of the potential pharmacodynamic components of Ling-gui-zhu-gan decoction.     

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.     

Identification of chemical components in Baidianling Capsule based on gas chromatography–mass spectrometry and high‐performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry

Baidianling Capsule, which is made from 16 Chinese herbs, has been widely used for treating vitiligo clinically. In this study, the sensitive and rapid method has been developed for the analysis of chemical components in Baidianling Capsule by gas chromatography–mass spectrometry in combination with retention indices and high‐performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry. Firstly, a total of 110 potential volatile compounds obtained from different extraction procedures including alkanes, alkenes, alkynes, ketones, ethers, aldehydes, alcohols, phenols, organic acids, esters, furans, pyrrole, acid amides, heterocycles, and oxides were detected from Baidianling Capsule by gas chromatography–mass spectrometry, of which 75 were identified by mass spectrometry in combination with the retention index. Then, a total of 124 components were tentatively identified by high‐performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry. Fifteen constituents from Baidianling Capsule were accurately identified by comparing the retention times with those of reference compounds, others were identified by comparing the retention times and mass spectrometry data, as well as retrieving the reference literature. This study provides a practical strategy for rapidly screening and identifying the multiple constituents of a complex traditional Chinese medicine.     

The application of electrospray ionization coupled to ultrahigh resolution mass spectrometry for the molecular characterization of natural organic matter

Mass spectrometry has recently played a key role in the understanding of natural organic matter (NOM) by providing molecular-level details about its composition. NOM, a complex assemblage of organic molecules present in natural waters and soils/sediments, has the ability to bind and transport anthropogenic materials. An improved understanding of its composition is crucial in order to understand how pollutants interact with NOM and how NOM cycles through global carbon cycles. In the past, low-resolution (>3000) mass analyzers have offered some insights into the structure of NOM, but emerging ultrahigh resolution (>200,000) techniques such as electrospray ionization (ESI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) have significantly advanced our knowledge of NOM chemistry. Here, a review of the recent literature on the advancements of NOM characterization and the applications of mass spectrometry to this central task is presented. Various methods for the analysis and display of the extremely complex mass spectra, such as the van Krevelen diagram and Kendrick mass defect analysis, are discussed. We also review tandem mass spectrometry techniques employed to gain structural information about NOM components. Finally, we show how ESI-FT-ICR-MS has been applied to examine specific issues that are important to the NOM scientific community, such as NOM reactivity, transport and fate, degradation, and existence of components, which are indicators of NOM origin. In general, ultrahigh resolution provided by FT-ICR-MS is essential for the complete separation of the thousands of peaks present in the complex NOM mixture and will clearly lead to additional future advancements in the areas of aquatic, soil, and analytical chemistry.     

类肝素化合物的傅立叶变换离子回旋共振-电喷雾质谱研究

采用负离子模式的电喷雾傅立叶变换离子回旋共振质谱(ESI-FTICR-MS)对3个合成的肝素类化合物DHα、THα和THβ进行了全扫描一级谱和持续非共振辐照碰撞诱导解离(SORI-CID)串联质谱分析。样品浓度10μmol/L,流动泵注射直接进样。化合物中的磺酸胺和磺酸酯结构容易在一般电喷雾条件下发生分解,失去一个或者多个SO3,一级全扫描谱图中得到的谱峰均是带有单电荷或者双电荷的准分子离子峰。在串联质谱中,部分双电荷离子发生解离时,其二级谱图中子离子由单电荷子离子和双电荷子离子共同组成。通过对谱峰的局部放大,利用同位素峰的峰间距,能直接给出子离子的带电荷情况。同时,结合FTICRMS提供的高质量精度质谱数据,能够对所选取母离子的碎裂途径进行确认。离子质荷比测量的平均误差小于3.0×10-6。为结构复杂的类肝素化合物的质谱分析提供了借鉴。     

沙特常压渣油超临界流体萃取分馏宽馏分中含硫化合物的分子表征

采用超临界流体萃取分馏(SFEF)装置,将沙特中质原油常压渣油(SZAR)按照分子大小和极性强弱进行多级萃取分馏,得到四个宽馏分和一个萃余残渣。考察了四个宽馏分沸程分布、密度、残炭值、黏度、相对分子质量、硫和氮含量以及结构族组成等基本性质均随萃取压力的变化趋势。采用甲基衍生化作用使含硫化合物转化为含有极性的甲基硫盐,结合正离子模式下的电喷雾(ESI)电离源的傅里叶变换离子回旋共振质谱(FT-ICR MS)分析各馏分中所包含的含硫化合物的分子组成。结果表明,超临界萃取分馏技术可以将馏分按照分子大小进行分离,且对于非烃类化合物具有富集作用。各个馏分中含量最高的均为包含一个硫原子的S1类化合物,且二苯并噻吩(DBE=6)类含量最高。馏分越重,S1、S2类化合物含量越高、种类越繁多、且缩合程度更高,包含的更多的大分子含硫化合物。     

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。     

傅里叶变换离子回旋共振质谱仪:过去、现在与未来

对傅里叶变换离子回旋共振高分辨率质谱仪的发展历程、串联质谱解离技术及最新的应用进行了详细描述,并对其发展趋势进行了展望。     

复方板蓝根颗粒化学成分的质谱研究

利用电喷雾多级串联质谱(ESI-MSn)和傅里叶变换离子回旋共振质谱(FT-ICR-MS)技术,对复方板蓝根颗粒经溶剂萃取后的95%(体积分数)醇提和水提部位的化学成分进行了系统研究,鉴定出多种氨基酸成分、糖及其衍生物、有机酸、氨基酸和单糖的梅拉德反应初级产物以及含硫化合物表告依春.该方法灵敏快速,适宜于中药提取物的化学成分分析.