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。     

Studies on Fragmentation of Peptide by Nano-electrospray Ionization Fourier Transform Ion Cyclotron Resonance Multi-stage Tandem Mass Spectrometry

The sequence analysis of peptides was performed by nano-electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry(Nano-ESI-FT-ICR-MSn) and several peptides were chosen as examples. With the aid of the collision induced dissociation(CID), FT-ICR provides not only precise mass/charge ratio, but also structure information of the selected peptides. The fragment ions were identified according to the observed molecular weights and peptide sequence was determined successfully. So Nano-ESI-FT-ICR-MSn is a useful tool for identification of the amino acid sequence of peptides with high confidence. Besides, a pathway for the dehydration of y ions without amino acids containing carboxylic acid under sustained off-resonance irradiation collision-induced dissociation(SORI-CID) condition was proposed.     

液相基质辅助激光解吸电离-傅里叶变换离子回旋共振质谱研究

选用液相基质制样,考察了激光强度、回旋池开门时间等因数对基质辅助激光解吸电离-傅里叶变换离子回旋共振质谱(MALDI—FT—ICR—MS)检测结果的影响,优化了实验条件。使用液相制样方法对5类实际样品进行了MALDI—FT-ICR—MS检测,结果表明：液相基质具有很好的通用性,质谱信号稳定、持久。利用FT-ICR—MS特有的超高分辨率与准确度,能够很准确地测定化合物组成。     

Synthesis of 1-(1-Adamantyl)-2-hydroxy-3-amino-3-R-propanones

Previously unknown cis-1-(1-adamantyl)-2,3-epoxy-3-R-propanones were highly selectively obtained by epoxidation of ,-unsaturated ketones with hydrogen peroxide in alkaline medium. The regioselectivity of the epoxide ring cleavage with amines (piperidine and morpholine) was studied.     

傅立叶变换离子回旋共振质谱法分析铝材封闭剂中的成分

该文采用傅立叶变换离子回旋共振质谱(FT-ICR-MS)技术,对一种铝材封闭剂(表面处理剂)中的未知成分进行了分析,发现了萘磺酸钠、醋酸镍、苯甲酸钠等成分。根据FT-ICR-MS测定得到的精确分子离子数据,以及同位素精细结构,推测出未知物离子分子式,再结合电感藕合等离子体质谱(ICP-MS)和气相色谱-质谱(GC-MS)分析,推断出未知成分的结构,确认其为萘磺酸钠等成分。文中还发现质谱图中有2组质量数相差62的簇离子:234.8、296.8、358.9和410.7、472.7、534.7,结合二级质谱分析,推断出这两组离子为醋酸镍与醋酸、苯甲酸加合产生的准分子离子,同时还产生二聚体、三聚体离子,合理地解析了质谱图中所出现的未知离子的归属。该研究对化工产品中未知物剖析及产品创新提供了一种新的思路和方法,并发现了镍金属离子与有机酸结合后在质谱中的离子化规律。     

Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometric Study on Sodium Azide Cluster Ions

Introduction Mass spectrometry (MS) has been an important technique for studying size-dependent cluster properties with unparalleled sensitivity, specificity, and versatil-ity.1,2 Especially Fourier transform ion cyclotron reso-nance (FT-ICR) MS offers the benefits of ultra-high mass resolving power, superior mass accuracy, and the ability of affording useful structure information with tandem MS. The introduction of electrospray ionization (ESI) as a gentle mode of ion generation for MS…     

Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results

We report relative dephasing cross sections for the 20 biogenic protonated amino acids measured using the cross sectional areas by Fourier transform ion cyclotron resonance (CRAFTI) technique at 1.9 keV in the laboratory reference frame, as well as momentum transfer cross sections for the same ions computed from Boltzmann-weighted structures determined using molecular mechanics. Cross sections generally increase with increasing molecular weight. Cross sections for aliphatic and aromatic protonated amino acids are larger than the average trend, suggesting these side chains do not fold efficiently. Sulfur-containing protonated amino acids have smaller than average cross sections, reflecting the mass of the S atom. Protonated amino acids that can internally hydrogen-bond have smaller than average cross sections, reflecting more extensive folding. The CRAFTI measurements correlate well with results from drift ion mobility (IMS) and traveling wave ion mobility (TWIMS) spectrometric measurements; CRAFTI results correlate with IMS values approximately as well as IMS and TWIMS values from independent measurements correlate with each other. Both CRAFTI and IMS results correlate well with the computed momentum transfer cross sections, suggesting both techniques provide accurate molecular structural information. Absolute values obtained using the various methods differ significantly; in the case of CRAFTI, this may be due to errors in measurements of collision gas pressure, measurement of excitation voltage, and/or dependence of cross sections on kinetic energy.

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Fourier Transform Ion Cyclotron Resonance Mass Resolution and Dynamic Range Limits Calculated by Computer Modeling of Ion Cloud Motion

Particle-in-Cell (PIC) ion trajectory calculations provide the most realistic simulation of Fourier transform ion cyclotron resonance (FT-ICR) experiments by efficient and accurate calculation of the forces acting on each ion in an ensemble (cloud), including Coulomb interactions (space charge), the electric field of the ICR trap electrodes, image charges on the trap electrodes, the magnetic field, and collisions with neutral gas molecules. It has been shown recently that ion cloud collective behavior is required to generate an FT-ICR signal and that two main phenomena influence mass resolution and dynamic range. The first is formation of an ellipsoidal ion cloud (termed “condensation”) at a critical ion number (density), which facilitates signal generation in an FT-ICR cell of arbitrary geometry because the condensed cloud behaves as a quasi-ion. The second phenomenon is peak coalescence. Ion resonances that are closely spaced in m/z coalesce into one resonance if the ion number (density) exceeds a threshold that depends on magnetic field strength, ion cyclotron radius, ion masses and mass difference, and ion initial spatial distribution. These two phenomena decrease dynamic range by rapid cloud dephasing at small ion density and by cloud coalescence at high ion density. Here, we use PIC simulations to quantitate the dependence of coalescence on each critical parameter. Transitions between independent and coalesced motion were observed in a series of the experiments that systematically varied ion number, magnetic field strength, ion radius, ion m/z, ion m/z difference, and ion initial spatial distribution (the present simulations begin from elliptically-shaped ion clouds with constant ion density distribution). Our simulations show that mass resolution is constant at a given magnetic field strength with increasing ion number until a critical value (N) is reached. N dependence on magnetic field strength, cyclotron radius, ion mass, and difference between ion masses was determined for two ion ensembles of different m/z, equal abundance, and equal cyclotron radius. We find that N and dynamic range depend quadratically on magnetic field strength in the range 1–21 Tesla. Dependences on cyclotron radius and Δm/z are linear. N depends on m/z as (m/z)^–2. Empirical expressions for mass resolution as a function of each of the experimental parameters are presented. Here, we provide the first exposition of the origin and extent of trade-off between FT-ICR MS dynamic range and mass resolution (defined not as line width, but as the separation between the most closely resolved masses).     

Syntheses of Heterocycles from the Sodium Salts of 3-(1-Adamantyl)-1-hydroxy-1-propen-3-one and 4-(1-Adamantyl)-1-hydroxy-1-buten-3-one

The interaction of the sodium salts of 3-(1-adamantyl)-1-hydroxy-1-propen-3-one and 4-(1-adamantyl)-1-hydroxy-1-buten-3-one with hydroxylamine, hydrazine, and guanidine leads to the synthesis of 5-(1-adamantyl)-5-hydroxy- and 5-(1-adamantylmethyl)-5-hydroxy-2-isoxazolines, 3-(1-adamantyl)- and 3-(1-adamantylmethyl)pyrazoles, 3-(1-adamantyl)-2-phenylpyrazole, and 4-(1-adamantyl)-2-amino- and 4-(1-adamantylmethyl)-2-aminopyrimidines.     

Favorskii Rearrangement in the Reaction of 3-(1-Adamantyl)-1-chloro-2-propanone with Amines

The reaction of 3-(1-adamantyl)-1-chloro-2-propanone with amines [diethylamine, (1-adamantyl)methylamine, p-toluidine, and piperidine] in diethyl ether at room temperature involves the Favorskii rearrangement and yields N,N-disubstituted amides of 3-(1-adamantyl)propanoic acid.     

Synthesis of 4-(1-Adamantyl)- and 4-(1-Adamantylmethyl)-substituted Halothiazoles

1-Adamantyl bromomethyl ketone and 1-adamantylmethyl chloromethyl ketone react with potassium thiocyanate in dimethylformamide to give the corresponding thiocyanatoketones which cyclize under the influence of HCl into 4-(1-adamantyl) and 4(-adamantylmethyl)chlorothiazole respectively. 4-(1-Adamantyl)-2-amino-5-bromothiazole and its N-derivative were synthesized by the reaction of 1-adamantyl dibromomethyl ketone with thioureas and N-substituted thiourea in acetonitrile.     

cAMP及其衍生物金属离子铬合物的核磁共振研究

本文报导用核磁共振谱研究了有重要生理意义的二价金属离子与cAMP及其衍生物双丁酰cAMP的相互作用,比较了环苷酸与金属络合时各谱线的化学位移值和谱线宽度。     

1-乙酰基-3-(2-羟基-4,6-二甲氧基苯基)-5-苯基-2-吡唑啉的合成及锌离子探针的研究

设计合成了1-乙酰基-3-(2-羟基-4,6-二甲氧基苯基)-5-苯基-2-吡唑啉(4), 测试了其紫外光谱和荧光光谱, 研究了其对锌离子的选择性识别作用. 结果表明, 化合物4作为锌离子荧光探针, 受常见离子的干扰较小, 对于锌离子有着较高的选择性和较低的检出限.     

直馏柴油中硫化物甲基锍盐合成及电喷雾-高分辨质谱分析

在四氟硼酸银的催化作用下,以碘甲烷对直馏柴油进行甲基衍生化反应,使其中的有机硫化物转变成极性较强的锍盐,再用电喷雾-傅立叶变换离子回旋共振质谱仪进行检测。结合气相色谱-脉冲火焰光度检测器(GC-PFPD)分析,研究不同类型的硫化物甲基衍生化反应的选择性和转化率。结果表明:柴油中硫化物在室温条件下容易与碘甲烷发生甲基化反应,大部分硫化物转化为锍盐,总转化率超过80%,苯并噻吩类比二苯并噻吩类更易发生甲基衍生化反应,转化率也相应较高。烷基二苯并噻吩不同取代位异构体间反应选择性存在较大差异,高分辨质谱分析结果表明,直馏柴油中存在环状硫醚类化合物。     

Characterization of O+ Ion-implanted Glassy Carbon Using the Superconducting Electron Cyclotron Resonance Ion Source and Selective Dopamine Detection

The O and N gas ions (O³⁺, O⁺, N²⁺, and N⁴⁺) were implanted on the glassy carbon surface employing the electron cyclotron resonance ion source, which were characterized using electrochemical and surface analysis methods. The modified electrode was examined for the catalytic oxidation of bioorganic molecules including dopamine, where the O⁺ ion implanted GC revealed the best catalytic performance. The XPS and Raman results represented that the ion implantation made enrichment in graphite nanocrystalline structure with edge plane, showing the enhanced electrochemical activity. It showed excellent performance for dopamine detection without significant interferences between 50.0 nM and 400.0 μM with the detection limit of 10.0±2.5 nM (95 % confidence level). The reliability of proposed electrode was evaluated by the real urine sample analysis.     

傅立叶变换离子回旋共振质谱法对赤灵芝的化学成分鉴定和指纹图谱研究

建立了基于傅立叶变换离子回旋共振超高分辨质谱(FTICR-MS)的赤灵芝化学成分鉴定和指纹图谱分析方法,并应用于不同产地赤灵芝样品的来源区分。样品采用50%甲醇进行回流提取后,以流动注射的进样方式进行直接质谱分析。以ESI离子源在负离子模式下进行检测,质荷比扫描范围为100～1 000 Da。采用精确分子量测定和碰撞诱导解离实验进行化学成分鉴定,通过与文献进行比对,共鉴定出63种化学成分(1种萜烯醛、3种糖、4种三萜醇、6种有机酸和49种三萜酸类成分)。采用聚类分析和主成分分析(PCA)对所获得的质谱指纹图谱进行统计学分析,在95%的置信区间下,多个批次不同产地的赤灵芝样品得到了较好的来源区分。研究结果表明该方法可实现赤灵芝的直接、快速、高效分析和指纹图谱研究,在中药分析领域有着广阔的应用前景。