气相中苯二聚体离子结构的串联质谱研究

应用碰撞诱导解离技术研究了苯自身化学电离条件下和苯化学电离（甲苯为反应气）条件下离子－分子反应产物ｍ／ｚ１５５和１５６离子的碰撞诱导解离（ＣＩＤ）破裂特性，并与化学电离条件下质子化联苯生成ｍ／ｚ１５５离子的ＣＩＤ碎裂反应相比较，获得了苯离子１－分子反应产物ｍ／ｚ１５５和１５６离子的结构信息。     

3-苯基-1-丁炔-3-醇质谱碎裂中[C8H7]^+的结构及分子内质子迁移反应

报道了3-苯基-1-丁炔-3-醇的常规电子轰击质谱(EIMS)。利用碰撞诱导解离(CID)技术研究了质谱碎裂过程中产生的[C8H7]^+的气相离子结构。同时, 氘代同位素交换、亚稳(MI)和CID实验进一步证实了m/z 103离子的形成并不是分子离子的质谱碎裂中顺次失去甲基自由基和中性CO分子的直接氢迁移的协同反应, 而是在失去CO分子前后发生了二次质子迁移反应的逐步过程。在此基础上提出了一种独特的双分子质子键合复合物中间体的碎裂机理。     

气相中卤代苯离子-分子反应产物的串联质谱研究

应用碰撞诱导解离技术研究了氯代苯、溴代苯和碘代苯离子-分子反应产物的碎裂反应特性,与联苯的分子离子和质子化溴代联苯的碰撞诱导解离谱比较获得了产物离子的结构信息.     

大黄酸ESI-IT MS质谱行为及碎片离子的量子化学研究

采用电喷雾-离子阱质谱(ESI-IT MS),获取大黄酸分子的一级质谱和多级质谱碰撞诱导解离下的碎片离子,以量子化学计算大黄酸分子及其主要碎片离子的质谱行为。通过对质谱离子几何参数、键断裂能、电荷变化、自旋密度以及前线分子轨道的分析,可得到m/z 282.8、256.9、238.9、210.8、192.8、182.8、166.8离子的稳定构型以及质谱裂解途径,从而较系统地解释了大黄酸分子在ESI-IT MS中的裂解行为。     

β-羰基酰胺类化合物的配位及晶体结构

为确认β-羰基酰胺类化合物与铜离子的配位位点,合成了6种β-羰基酰胺类配体L1～L6,分别与Cu(Ⅱ)进行配位反应.对生成的配合物进行单晶培养,并采用X射线衍射仪测定了单晶结构.结果表明,只有配体L6(2-苯甲酰乙酰苯胺)的铜配合物能够得到单晶.在其单晶中,Cu(Ⅱ)离子与来自2个配体的4个氧原子配位形成长方形的构型;配合物中存在分子内氢键、分子间氢键和π-π相互作用.     

苯二氮卓类新精神活性物质Flubromazolam的快速检测

建立了气相色谱-质谱(GC-MS)和超高效液相色谱-串联四极杆飞行时间质谱(UPLC-Q-TOF MS)技术联合鉴定检材中flubromazolam的方法。未知样品用甲醇和水提取,取上清液,采用GC-MS和UPLC-Q-TOF MS进行分析。经GC-MS检测,保留时间为17.96 min的未知组分的质谱碎片主要特征离子峰有m/z 222,341,343,370,372,111,102,75。经UPLC-QTOF M S检测,保留时间为4.99 min的未知组分的准分子离子峰为m/z 371.0298,碰撞诱导解离(CID)模式下二级质谱主要离子有m/z 343.0114,302.9928,292.1118,263.0982,237.0951,223.0670。经美国缉毒署毒品分析谱库、缴获毒品分析科学工作组(SWGDRUG)分析谱库检索和文献查询获得的信息资料进行比对,确认目标物为flubromazolam。     

一种聚酰胺-胺型树枝状分子的电喷雾离子阱质谱分析

以己二胺为分子内核,室内合成了一类支化代数为1.0G的聚酰胺-胺型树枝状分子己二胺四丙酰胺二胺(1.0G支化物)。应用ESI-MS技术研究并表征了该支化物的分子结构与正、负离子扫描条件下的主要特征碎片离子及主要裂解途径。1.0G支化物在正、负离子模式下均可以得到较佳的质谱信息。在正离子模式下,容易与H+形成[M+H]+准分子离子,并裂解形成碎片m/z573.41,m/z 555.40,m/z 471.30,m/z 459.30,m/z 453.28,m/z 369.17,m/z357.16等。在负离子模式下丢失一个H+,形成[M-H]-准分子离子,并进一步碎裂成碎片m/z 571.43,m/z 511.29,m/z 457.20,m/z 397.05,m/z 342.99,m/z240.84等。分别阐述了1.0G支化物在正、负离子模式下的电喷雾质谱裂解规律并对主要特征碎片离子进行了结构归属,为进一步对聚酰胺-胺型树枝状分子的表征与结构指认提供了有价值的依据。     

3-羧基-1,2,4-三氮唑Mn~Ⅱ配合物的合成、结构及荧光性质

为了探讨3-羧基-1,2,4-三氮唑(MTC)配合物的性质。本文采用水热法合成了一个结构新颖的配合物[Mn(C_3H_2N_3O_2)_2(H_2O)_2]。通过红外光谱(IR)、元素分析、热重分析(TGA)和粉末X射线衍射(PXRD)等技术手段表征了配合物的结构和性能。X射线单晶衍射分析表明,配合物为一单核结构,属于单斜晶系P21/c空间群.MnⅡ离子采取六配位,每个Mn离子位于反演中心,分别与两个MTC配体中的1个O和1个N原子螯合配位,同时还与2个水分子配位,形成一个稍微变形八面体构型结构。同时,在配合物中存在着丰富的氢键和弱的π-π作用力,通过分子间氢键和弱π-π相互作用形成一个三维网络结构。固体荧光研究表明,配合物的发射峰为517nm,较配体发生7nm蓝移。该研究对新型金属有机配合物荧光材料的开发具有一定的指导和借鉴意义。     

高效液相色谱-质谱法对饲料及食品添加剂中三聚氰胺的测定

建立了饲料中三聚氰胺的高效液相色谱-质谱测定方法.色谱条件:Kromasil C18柱(4.6 mm×250mm,5 μm),流动相:乙腈-0.1%(体积分数)甲酸(体积比5:95),流速0.4 mL/min.采用正离子模式的电喷雾质谱检测,以一级质谱得到的准分子离子m/z 127作为母离子,进行碰撞诱导解离(CID)二级质谱(MS2)分析,选择母离子和MS2的碎片离子m/z 85、109定性确证,提取m/z 85、109、127三个离子质量色谱峰面积定量.实验优化了质谱条件.线性范围为0.01～0.5 mg/L,检出限0.01 mg/L(S/N=3),回收率为80%～99%.     

卤代芳香族羧酸与含氮配体合成镧系配合物的结构、热化学和荧光性质（英文）

采用室温溶液挥发法合成了五种结构新颖的镧系配合物,其结构通式为[Ln(2,4-DFBA)₃(phen)]₂ (Ln=Sm 1, Eu2, Er 3, 2,4-DFBA为2,4二氟苯甲酸的简写,phen为1,10-菲啰啉的简写),[Ln(2-Cl-6-FBA)₂(terpy)(NO₃)(H₂O)]₂ (Ln=Tb4, Dy 5, 2-Cl-6-FBA为2-氯-6-氟苯甲酸的简写, terpy为2,2’:6’2’’-三联吡啶的简写)。五个配合物可以分为两个系列,使用不同的镧系离子作为中心离子。通过X射线单晶分析,5种配合物均属于单斜晶系,空间群为P21/n。配合物1,2和配合物3虽然具有相同的分子通式,但配位方式明显不同,形成了前者为9配位的松饼型,后者是8配位的双帽三棱柱几何构型。二维面状超分子结构的形成方式也明显不同,区别在于配合物1和2通过微弱的π-π堆积作用形成。配合物4和5是同构的,结构中引入了硝酸根离子较为有趣,通过C―H···F氢键和π-π堆积作...     

用Fourier变换质谱研究苯胺衍生物的自身化学电离

报导了3-苯甲酰氧基苯胺和P-溴代苯胺在FT质谱中的自身化学电离, 采用多共振离子消除技术研究离子-分子反应机理. 着重探讨系列离子m/z 200, 290, 380和470的生成机理.     

Nitrosonium complexes of [2.2]paracyclophane

The reaction of [2.2]paracyclophane with nitrosonium tetrachloroaluminate was studied by NMR (¹H, ¹³C) spectroscopy using deuterium isotopic perturbation technique. The resulting cationic complexes containing one and two nitrosonium ions are involved in fast (on the NMR time scale) interconversion. Quantum-chemical calculations performed on the DFT level (using triple zeta basis set) indicate the higher stability of 2η single-charged π-complexes relative to σ complexes corresponding to the addition of NO⁺ ion at the ipso and ortho positions. The formation of the single-charged π-complex is energetically more favorable, compared to the double-charged π-complex. The affinity of NO⁺ for [2.2]paracyclophane is much greater than for p-xylene, presumably due to stacking interaction between the aromatic rings in the π-complex.     

Utility of solution electrochemistry mass spectrometry for investigating the formation and detection of biologically important conjugates of acetaminophen

On-line formation and detection of glutathione and cysteine conjugates of acetaminophen were accomplished by the interfacing of a coulometric electrochemical cell with a thermospray mass spectrometer in a flow-injection experiment using a liquid chromatographic pump. Formation of the conjugates occurred only after acetaminophen was oxidized electrochemically by a two-electron transfer to N-acetyl-p-benzoquinoneimine and reacted in a mixing tee with either glutathione or cysteine. The newly formed conjugate was detected by thermospray mass spectrometry by observing the [M + H]+ ion for the acetaminophen-glutathione conjugate at m/z 457, or the [M + H]+ ion for the acetaminophen cysteine conjugate at m/z 271. Both the glutathione and cysteine conjugates produced a common fragment ion at m/z 184. The on-line reaction of glutathione and electrochemically generated N-acetyl-p-benzoquinoneimine was monitored at varying pH. At pH 8.5 the ion intensity for the acetaminophen-glutathione conjugate was greater than at lower pH, indicating that lower proton concentration enhanced the reaction of glutathione with N-acetyl-p-benzoquinoneimine. This on-line electrochemical-thermospray mass spectrometric method demonstrated that acetaminophen conjugates may be formed and detected in the time frame of 1 s.     

Characterization of sodiated glycerol phosphatidylcholine phospholipids by mass spectrometry

Fast atom bombardment mass spectrometry in the positive mode was used for the characterization of sodiated glycerol phosphatidylcholines. The relative abundance (RA) of the protonated species is similar to the RA of the sodiated molecular species. The sodiated fragment ion, [M + Na - 59](+), corresponding to the loss of trimethylamine, and other sodiated fragment ions, were also observed. The decomposition of the sodiated molecule is very similar for all the studied glycerol phosphatidylcholines, in which the most abundant ion corresponds to a neutral loss of 59 Da. Upon collision-induced dissociation (CID) of the [M + Na](+) ion informative ions are formed by the losses of the fatty acids in the sn-1 and sn-2 positions. Other major fragment ions of the sodiated molecule result from loss of non-sodiated and sodiated choline phosphate, [M + Na - 183](+), [M + Na - 184](+.) and [M + Na - 205](+), respectively. The main CID fragmentation pathway of the [M + Na - 59](+) ion yields the [M + Na - 183](+) ion, also observed in the CID spectra of the [M + Na](+) molecular ion. Other major fragment ions are [M + Na - 205](+) and the fragment ion at m/z 147. Collisional activation of [M + Na - 205](+) results in charge site remote fragmentation of both fatty acid alkyl chains. The terminal ions of these series of charge remote fragmentations result from loss of part of the R(1) or R(2) alkyl chain. Other major informative ions correspond to acylium ions.     

Radial stratification of ions as a function of mass to charge ratio in collisional cooling radio frequency multipoles used as ion guides or ion traps

Collisional cooling in radio frequency (RF) ion guides has been used in mass spectrometry as an intermediate step during the transport of ions from high pressure regions of an ion source into high vacuum regions of a mass analyzer. Such collisional cooling devices are also increasingly used as 'linear', two-dimensional (2D) ion traps for ion storage and accumulation to achieve improved sensitivity and dynamic range. We have used the effective potential approach to study m/z dependent distribution of ions in the devices. Relationships obtained for the ideal 2D multipole demonstrate that after cooling the ion cloud forms concentric cylindrical layers, each of them composed of ions having the same m/z ratio; the higher the m/z, the larger is the radial position occupied by the ions. This behavior results from the fact that the effective RF focusing is stronger for ions of lower m/z, pushing these ions closer to the axis. Radial boundaries of the layers are more distinct for multiply charged ions, compared to singly charged ions having the same m/z and charge density. In the case of sufficiently high ion density and low ion kinetic energy, we show that each m/z layer is separated from its nearest neighbor by a radial gap of low ion density. The radial gaps of low ion population between the layers are formed due to the space charge repulsion. Conditions for establishing the m/z stratified structure include sufficiently high charge density and adequate collisional relaxation. These conditions are likely to occur in collisional RF multipoles operated as ion guides or 2D ion traps for external ion accumulation. When linear ion density increases, the maximum ion cloud radius also increases, and outer layers of high m/z ions approach the multipole rods and may be ejected. This 'overfilling' of the multipole capacity results in a strong discrimination against high m/z ions. A relationship is reported for the maximum linear ion density of a multipole that is not overfilled.     

Programmable gate delayed ion mobility spectrometry-mass spectrometry: a study with low concentrations of dipropylene-glycol-monomethyl-ether in air

The concept of using a short ionisation event, in this case a pulsed corona discharge, in conjunction with programmed gate delay is described. This technique is proposed for the selective study of different ionisation processes within the reaction region of an ion mobility spectrometer. The utility of such an approach was tested in a study of the ionisation of dipropylene-glycol-monomethyl-ether (DPM); a compound commonly used to test the operation of ion mobility spectrometers. Dipropylene-glycol-monomethyl-ether at a concentration of 113 microg m(-3) in air, with a water level of 75 mg m(-3) in air, was analysed using a switchable, high resolution ion mobility spectrometer, operating in the positive mode at 40 degrees C at ambient pressure. The ion mobility spectrometer was fitted with a pulsed corona discharge ionisation source, doped with ammonia at a concentration of 1.3 mg m(-3) in the reaction region, and interfaced to a mass spectrometer. Synchronisation of the ionisation event to the operation of the shutter grids for the drift region enabled different parts of the product ion population to be injected into the drift tube, and programming the gate delays produced a map of the gate delay verses drift time response surface. Ammonium bound dipropylene-glycol-monomethyl-ether was observed, [(DPM)NH4]+ (m/z 166) as well as the ammonium bound dimer [(DPM)2NH4]+ (m/z 314), the same as those observed with a 63Ni source. Two other species were also observed, but their molecular identity was not elucidated. One of them m/z 146, also observed with 63Ni, formed ammonium bound ions [(m/z 146)NH4]+ (K0= 1.49 cm2 V(-1) s(-1)), ammonium bound dimer ions [(m/z 146)2NH4]+(K0= 1.18 cm2 V(-1) s(-1)) and a mixed cluster ion with DPM [(m/z 146)(DPM)NH4]+(K0= 1.18 cm2 V(-1) s(-1)); while the other, m/z 88 a decomposition product, formed ammonium bound monomer [(m/z 88)NH4]+(K0= 1.68 cm2 V(-1) s(-1)), dimer ions [(m/z 88)2NH4]+(K0= 1.40 cm2 V(-1) s(-1)) and a mixed cluster ion containing DPM and ammonium, [(DPM)(m/z 88)2NH4]+(K0= 1.40 cm2 V(-1) s(-1)). The assignment of responses to these ions required the additional dimensionality in the data provided from the gate delay studies. The relationships evident in the programmable gate delay data enabled these ions to be differentiated from alternative assignments of possible nitrogen clusters, formed at the interface of the mass spectrometer.     

Nitramine anion fragmentation: A mass spectrometric and Ab initio study

The fragment ion formation characteristics of the radical anions generated from hexahydro-1,3,5-trinitrotriazine (RDX) and its three nitroso metabolites were studied using GC/MS with negative chemical ionization (NCI) to understand the fragmentation mechanisms responsible for the formation of the most abundant ions observed in their NCI mass spectra. Ab initio and density functional theory calculations were used to calculate relative free energies for different fragment ion structures suggested by the m/z values of the most abundant ions observed in the NCI mass spectra. The NCI mass spectra of the four nitramines are dominated by ions formed by the cleavage of nitrogen-nitrogen and carbon-nitrogen bonds in the atrazine ring. The most abundant anions in the NCI mass spectra of these nitramines have the general formulas C(2)H(4)N(3)O (m/z 86) and C(2)H(4)N(3)O(2) (m/z 102). The analyses of isotope-labeled standards indicate that these two ions are formed by neutral losses that include two exocylic nitrogens and one atrazine ring nitrogen. Our calculations and observations of the nitramine mass spectra suggest that the m/z 86 and m/z 102 ions are formed from either the (M--NO)(-) or (M--NO(2))(-) fragment anions by a single fragmentation reaction producing neutral losses of CH(2)N(2)O or CH(2)N(2)O(2) rather than a set of sequential reactions involving neutral losses of HNO(2) or HNO and HCN.     

Tandem mass spectrometry of intact oxidation products of diacylphosphatidylcholines: evidence for the occurrence of the oxidation of the phosphocholine head and differentiation of isomers

Three glycerophosphatidylcholine (GPC) phospholipids (oleoyl-, linoleoyl- and arachidonoylpalmitoylphosphatidylcholine) were oxidized under Fenton reaction conditions (H(2)O(2) and Fe(2+)), and the long-chain oxidation products were detected by electrospray mass spectrometry (ES-MS) and characterized by ES-MS/MS. The intact oxidation products resulted from the insertion of oxygen atoms into the phospholipid structure. The tandem mass spectra of the [MNa](+) molecular ion showed, apart from the characteristic fragments of GPC, fragment ions resulting from neutral losses from [MNa](+), and combined with loss of 59 and 183 Da from [MNa](+). These ions resulted from cleavage of the bond near the hydroxy group by a charge-remote fragmentation mechanism, allowing its location to be pinpointed. The fragments thus formed reflected the positions of the double bonds and of the derivatives along the unsaturated fatty acid chain, giving very useful information, as they allowed the presence of structural isomers and positional isomers to be established. The identification of the fragment ion at m/z 163, which is 16 Da higher than the five-membered cyclophosphane ion (m/z 147), in some tandem mass spectra, is consistent with the oxidation of the phosphocholine head. Some ions were found to occur with the same m/z value; in two of the phospholipids and based on the MS/MS data, structural and positional isomers were differentiated. Our findings indicate that MS/MS is a valuable tool for the identification of the wide complexity of structural features occurring in oxidized phosphatidylcholines during lipid peroxidation in cellular membranes.     

电喷雾质谱法分析假单胞菌的代谢产物鼠李糖脂

采用电喷雾质谱(ESI-MS)结合碰撞诱导解离(CA)技术,分析了假单胞菌BS-03,利用甘油产的鼠李糖脂提取物。根据一级和二级质谱图确定了提取物中存在23种鼠李糖脂组分,主要由4种物质(RhC10、RhC10C10、Rh2C10和Rh2C10C10)构成,其中前3种的丰度较高也较平均。该提取物中单鼠李糖脂的含量高于双鼠李糖脂,并且双鼠李糖脂的二级质谱图中普遍存在强度较高的m/z为205、247的特征碎片离子,而单鼠李糖脂中却不存在此特征碎片离子。     

Detection and characterization by mass spectrometry of radical adducts produced by linoleic acid oxidation

The formation of linoleic acid radical species under the oxidative conditions of the Fenton reaction (using hydrogen peroxide and Fe (II)) was monitored by FAB-MS and ES-MS using the spin trap 5,5-dimethyl-1-pyrrolidine-N-oxide, DMPO. Both the FAB and ES mass spectra were very similar and showed the presence of ions corresponding to carbon- and oxygen centered spin adducts (DMPO/L*, DMPO/LO*, and DMPO/LOO*). Cyclic structures, formed between the DMPO oxygen and the neighboring carbon of the fatty acid, were also observed. Electrospray tandem mass spectrometry of these ions was performed to confirm the proposed structure of these adducts. All MS/MS spectra showed an ion at m/z 114, correspondent to the [DMPO + H]+, and a fragment ion due to loss of DMPO (loss of 113 Da), confirming that they are DMPO adducts. ES-MS/MS spectra of alkoxyl radical adducts (DMPO/LO*) showed an additional ion at m/z 130 [DMPO - O + H]+, while ES MS/MS of peroxyl radical adducts (DMPO/LOO*) showed a fragment ion at m/z 146 [DMPO - OO + H]+, confirming both structures. Other fragment ions were observed, such as alkyl acylium radical ions, formed by cleavage of the alkyl chain after loss of water and the DMPO molecule. The identification of fragment ions observed in the MS/MS spectra of the different DMPO adducts suggests the occurrence of structural isomers containing the DMPO moiety both at C9 and C13. The use of ES tandem mass spectrometry, associated with spin trapping experiments, has been shown to be a valuable tool for the structural characterization of carbon and oxygen-centered spin adducts of lipid radicals.