Mass Spectra of Substituted N-Alkylpyrroles and Related Compounds

Under El conditions, substituents on N-alkylpyrroles affect fragmentation of the alkyl groups. The electron-withdrawing character of the cyano group retarded formation of a N-methylene cation, and a labile substituent, i.e., -CHO, -CH₂COOMe, competed with an N-alkyl group to be a initial fragmentation center, MNDO calculation of the heat of formation of possible fragment ions showed that protonated pyridine is the most stable among the isobaric ions.     

噻二唑基取代硫脲化合物的低分辨质谱研究

研究了两类１９种取代硫脲类化合物的低分辨ＥＩ质谱。其主要裂解方式为噻二唑环开裂，硫代羰基裂解及中性丢失。杂原子的存在对质谱裂解有重要影响     

Interpretation and Deconvolution of Nanodisc Native Mass Spectra

Nanodiscs are a promising system for studying gas-phase and solution complexes of membrane proteins and lipids. We previously demonstrated that native electrospray ionization allows mass spectral analysis of intact Nanodisc complexes at single lipid resolution. This report details an improved theoretical framework for interpreting and deconvoluting native mass spectra of Nanodisc lipoprotein complexes. In addition to the intrinsic lipid count and charge distributions, Nanodisc mass spectra are significantly shaped by constructive overlap of adjacent charge states at integer multiples of the lipid mass. We describe the mathematical basis for this effect and develop a probability-based algorithm to deconvolute the underlying mass and charge distributions. The probability-based deconvolution algorithm is applied to a series of dimyristoylphosphatidylcholine Nanodisc native mass spectra and used to provide a quantitative picture of the lipid loss in gas-phase fragmentation.

几种挥发性有机酚的离子淌度谱测定

应用离子淌度谱仪在负高压方式下测得苯酚、２－氯代酚、２，４－二氯代酚及五氯代酚的折合淌度值分别为２．１２、２．０１、１．９３、１．７４ ｃｍ２Ｖ－１ｓ－１，检测限分别为 １．０、０．１、０．５、０．５μｇ／Ｌ，２－氯代酚、２，４－二氯代酚的二聚体的折合淌度值分别为 １．６０、１．４７ｃｍ２Ｖ１ｓ１，并对苯酚、２－氯代酚和２，４－二氯代酚的混合物进行了分析测定，并讨论了淌度值与分子量、分子形状之间的关系。     

The Features of Organoelement Compounds Conformational Analysis

Abstract

Conformational analysis of organoelement compounds (OEC) has anumber of features. There are some common characteristics of OEC electronic structure to be of importance:     

Analysis of Mass Spectra of Azobenzene Compounds with

“推－拉”型偶氮苯化合物分子的共振结构决定了其关键碎裂方式,有内氢键作用时偶氮则附着于给电子端,而后续的碎裂过程则遵循各自主要官能团的裂解规律。     

Mass Spectra and Ion Collision Cross Sections of Hemoglobin

Mass spectra of commercially obtained hemoglobin (Hb) show higher levels of monomer and dimer ions, heme-deficient dimer ions, and apo-monomer ions than hemoglobin freshly prepared from blood. This has previously been attributed to oxidation of commercial Hb. Further, it has been reported that that dimer ions from commercial bovine Hb have lower collision cross sections than low charge state monomer ions. To investigate these effects further, we have recorded mass spectra of fresh human Hb, commercial human and bovine Hb, fresh human Hb oxidized with H₂O₂, lyophilized fresh human Hb, fresh human Hb both lyophilized and chemically oxidized, and commercial human Hb oxidized with H₂O₂. Masses of α-monomer ions of all hemoglobins agree with the masses expected from the sequences within 3 Da or better. Mass spectra of the β chains of commercial Hb and oxidized fresh human Hb show a peak or shoulder on the high mass side, consistent with oxidation of the protein. Both commercial proteins and oxidized fresh human Hb produce heme-deficient dimers with masses 32 Da greater than expected and higher levels of monomer and dimer ions than fresh Hb. Lyophilization or oxidation of Hb both produce higher levels of monomer and dimer ions in mass spectra. Fresh human Hb, commercial human Hb, commercial bovine Hb, and oxidized commercial human Hb all give dimer ions with cross sections greater than monomer ions. Thus, neither oxidation of Hb or the difference in sequence between human and bovine Hb make substantial differences to cross sections of ions.     

羟甲基取代香豆素化合物的质谱

羟甲基取代香豆素化合物是亮菌甲素的同类物,由于亮菌甲素治疗胆道感染有较好的效果,而引起医学和化学界的重视,对从天然产物中提取和分离亮菌甲素及香豆素衍生物的合成进行了很多研究工作,关于香豆素及其衍生物的质谱亦有报道。     

用高分辨质谱研究二茂铁类化合物

研究了八种N－二茂铁甲基苯胺衍生物的电子电离质谱（EI－MS），并与快原子轰击质谱（FAB－MS）作了比较，讨论了这些化合物的质谱特征。通过精确质量测量，确认了M^ -2 OH离子，并采用碰撞诱导裂解（CID）探讨了化合物质谱中主要离子间的关系。     

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。     

微波等离子炬质谱负模式检测水中常见过渡金属离子

研究了负离子模式下锰、铁、钴、镍、铜和锌等常见过渡金属的微波等离子体炬(MPT)质谱特征,阐明了这些金属元素在MPT中形成阴离子的规律;初步得出饮用水中这些金属元素的最低检出限(LOD)均在约20μg/L量级,为实际检测这些金属元素奠定了基础.     

一些有机硅立体异构体的氧化亚氮负化学电离质谱研究

本文以氧化亚氮(N_2O)为反应气首次研究了一些有机硅立体异构体的负化学电离(NCI)质谱。反应离子(Reactant ions)和样品分子中硅及活性氢原子作用分别产生加合离子[M+O]~-和准分子离子[M-H]~-,它们的碎裂过程显示一定的立体专一性,为这些立体异构体的辨析提供了判据。     

The Photooxidation of Some Anthryl Phosphorus Compounds

Abstract

The photo-oxidation of anthryl phosphorus compounds occurs via a Type II process. All products observed can be accounted for by involving a 9, 10-endoperoxide, which may subsequently fragment, resulting in cleavage of the phosphorus moiety from the anthracene nucleus.     

Investigation of Spectra（NMR,Mass）of Some Fe3S3Cluster Compounds

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Electron Impact Mass Spectra of Some Arylpyridines

The mass spectra of 56 arylpyridines were studied under EI conditions. The fragmentations of this series of compounds are relatively simple because of a stable skeleton containing two aromatic rings. The orientations of cleavage of the methoxyl and methoxycarbonyl groups strongly depend on their position on the pyridine ring and can be applied to the differentiation of the isomers.     

Photoelectron Spectra of Nonmetal Compounds and Their Interpretation by MO Models

The results of (low energy) photoelectron spectroscopy render possible a better appreciation of the “Nature of the Chemical Bond”. The application of this new experimental method is demonstrated utilizing representative compounds of the nonmetal elements, and a close symbiosis delineated with molecular orbital models. In particular, general consequences are discussed concerning electron deficiency, σ- and π-interactions, electron pair delocalization, and substituent effects or geometric perturbations. Photoelectron spectroscopic ionization energies permit evaluation of parameters for specified molecular groups, allow correlation with numerous other experimental data, and are didactically valuable in the teaching of general chemistry.     

取代螺环戊烷的电子轰击和化学电离正,负离子质谱

本文报道了苯取代螺环戊烷衍生物的电子轰击(EI)正离子和化学电离正、负离子(PNCI)质谱。通过亚稳离子测定,研究了该类化合物的裂解机理。在卤代螺环戊烷的EI质谱中,分子离子峰都很弱,甚至不出现M 离子。其特征离子为[M-X]~ 、[M-2X] 和[M-X-HX]~ 。CI正离子谱有较强的[M H]~ 、[M-2X]~ 和[M-x]~ ,CI负离子谱的特征离子为[M X]~-,它们在多数情况下为基峰离子,另外还出现HX_2~-或X~-离子。     

含酯糖链皂甙的负离子快原子轰击质谱分析

本实验用负离子快原子轰击(FAB)法测定了8个含酯糖链的双糖链皂甙样品,给出了明显的脱质子分子离子峰,由碎片离子峰可推测糖基的连接顺序;不仅对难挥发、热不稳定和极性大的样品可直接进样分析,而且对在酯糖链皂甙中出现以酯裂解为基峰的碎片,还可初步确定糖链在甙元上的连接位置。     

Thermal Behaviour of Some Organ0 Phosphorus Compounds

Abstract

So far organophosphorus chemists have been interested in synthesizing low coordinated phosphorus compounds and in studying them in solution at temperatures rarely above 300 °C. As a matter of fact there are few reports on the behaviour of dicoordinated phosphorus molecules at temperatures above 500 °C under low pressure. Another interesting point is that such a study would allow to assess the correla- tion between mass spectral processes and thermal ones.