咪唑基引起缩合试剂3-(二乙氧基磷酰基)-氧-1,2,3-苯并三嗪-4(3H)-酮(DEPBT)的副反应

当用DEPBT作为缩合试剂合成含组氨酸的肌肽(β-Ala-His)衍生物时, 又偶然发现了另一个副反应. 在这个反应中, 没有得到预期的肌肽产物, 而是生成了一个结构与DEPBT相关的副产物EODhbt(3-乙氧基-3,4-二氢-1,2,3-苯并三嗪-4-酮). 本文报道了此副产物的发现、 结构鉴定及影响副反应的各种因素. 这对深入了解DEPBT的反应特性, 并且在含组氨酸的多肽合成中更有效地应用DEPBT提供了有用的信息.     

紫外线激活氚原子—制备氚标记单磷酸阿糖腺苷的研究

本文采用紫外线激活氚原子的方法,进行氚-氢同位素交换反应,制得氚标记单磷酸阿糖腺苷(9—~3H—mparaA)。产品的纯度是层析纯;放射性比活度16GBq.m mol~(-1);放射化学纯度92.0%。本法的优点是:交换反应温和、反应时间较短、不易破坏生物活性、引起的副产物少、产品分离和纯化较方便。     

1,10-邻菲咯啉-5,6-二酮制备反应中副产物的形成与控制

由1,10-邻菲咯啉合成1,10-邻菲咯啉-5,6-二酮反应的副产物的形成与控制研究表明,1,10-邻菲咯啉在5,6位二酮化反应中的副反应产物及主产物分离时产生的副产物均为4,5-二氮杂芴-9-酮,二酮化反应条件(包括作为氧化剂的强混合酸H2SO4/HNO3的加入量、时间和温度)和主产物分离时体系的酸度对副产物的形成有重要影响,优化了二酮化反应条件和产物分离时的体系pH控制范围。在此优化条件下,可有效控制副产物的形成,使主产物1,10-邻菲咯啉-5,6-二酮的收率达到92%以上。     

丁腈橡胶和聚乙二醇增韧环氧树脂制备胶粘剂及性能研究

本文在加热下环氧树脂(Polyethylene Glycol, EP)开环与端羧基丁腈橡胶(carboxyl-terminated Butadiene acrylonitrile, CTBN)与发生酯化反应生成预聚物,然后选用单一固化剂聚醚胺(Polyetheramine, D400)和混合固化剂聚乙二醇(Polyethylene Glycol, PEG,Mn=2000)与二乙基甲苯二胺(Diethyltoluene diamine, DETDA)作用下固化及粘接木块。重点探讨CTBN、EP、D400和PEG与DETDA各组成的用量对环氧树脂基粘胶性能的影响,并通过红外判定主要官能团反应,重点探讨胶粘固化物的润湿性、吸水性、拉伸强度和热重手段评价其环氧树脂粘胶性能。结果表明随着CTBN用量的增加,增韧环氧树脂的固化效果越来越好,但是增加到一定程度,有副反应的作用导致其固化效果与粘性都会逐渐降低。结论：对固化物进行表征综合评价,CTBN、EP和固化剂的质量比为1∶5∶2时,其粘性最强,韧性最高,进一步研究有望获得市场欢迎的产品。     

液相色谱-电喷雾质谱联用研究原花青素B3苄硫醇降解产物及反应条件

采用高效液相色谱-电喷雾串联质谱技术分析了原花青素B3苄硫醇降解过程的目标化合物和副反应产物,比较了不同反应条件对产物生成的影响。延伸单元的杂环裂解产物是反应的主要副产物,占副产物总量的50%以上;表异构化反应主要发生在末端单元。不同硫解条件对末端单元表异构化反应及硫解产率影响显著;在40℃、30 m in条件下,末端单元表异构化率最低(2.2%),硫解产率最高(88.7%),聚合度计算为2.1,适用于原花青素的定性、定量分析。     

沃特世为您提供猪肉中“瘦肉精”残留检测方案

近日来,"瘦肉精"事件的发生使人们再次将注意力集中到动物体内的β-受体激动剂的检测。常说的"瘦肉精"是一类动物用药,例如莱克多巴胺(Ractopamine)及克伦特罗(Clenbuterol)等。沃特世作为色谱分析行业的领导者,再一次展现了本公司集成样品前处理SPE产品、色谱产品、质谱产品于一体的技术优势,在第一时间推出了包含前处理在内的     

1,5-苯并硫氮杂(艹卓)-β-内酰胺的合成及其副产物的研究

以3-(3S-叔丁氧基)丁二酰亚胺基乙酰氯作为烯酮的来源,和1,5-苯并硫氮杂(艹卓)反应合成了4个具有光学活性的新型1,5-苯并硫氮杂(艹卓)-β-内酰胺衍生物.通过1H NMR,IR,MS谱和元素分析对其结构进行了表征,在得到目标产物的同时还得到了该反应的另外两个副产物,并且通过单晶X射线衍射确定了这两个副产物的结构.     

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。     

气色相谱-质谱法测定化妆品中的氯霉素

氯霉素是一种广谱抗生素,化妆品卫生规范规定氯霉素等抗生素为禁用物质.关于氯霉素的检测多采用高效液相色谱(HPLC)[1]和高效液相色谱-质谱(HPLC-MS)[2] 测定,或者经N,O-双三甲基硅烷基-三氟乙酰胺(BSTFA)、三甲基氯硅烷(TMCS)等硅烷化[3-4]后进行气相色谱(GC)、GC-MS测定.本文建立了采用较为普通的乙酸酐试剂进行衍生化,然后用GC-MS测定的方法.将该法应用于化妆品中氯霉素的检测,取得了较好的效果.     

鲜湿米粉中两种乳酸链球菌素的HPLC-MS/MS检测方法

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时测定鲜湿米粉中乳酸链球菌素A(Nisin A)和乳酸链球菌素Z(Nisin Z)的分析方法。样品经p H 3.0的水(甲酸调节p H值)提取,以Hilic Plus色谱柱分离待测物,在电喷雾正离子化模式下,采用多反应监测(MRM)模式检测。结果表明,Nisin A和Nisin Z在100~2 000μg/L范围内线性关系良好,相关系数均大于0.999,方法检出限分别为0.01、0.02 mg/kg,回收率为95.6%~107.0%,RSD均小于2.0%。该方法准确、可靠,适用于鲜湿米粉中Nisin A和Nisin Z的含量检测。     

Practical approaches to the ESI‐MS analysis of catalytic reactions

Electrospray ionization mass spectrometry (ESI‐MS) is a soft ionization technique commonly coupled with liquid or gas chromatography for the identification of compounds in a one‐time view of a mixture (for example, the resulting mixture generated by a synthesis). Over the past decade, Scott McIndoe and his research group at the University of Victoria have developed various methodologies to enhance the ability of ESI‐MS to continuously monitor catalytic reactions as they proceed. The power, sensitivity and large dynamic range of ESI‐MS have allowed for the refinement of several homogenous catalytic mechanisms and could potentially be applied to a wide range of reactions (catalytic or otherwise) for the determination of their mechanistic pathways. In this special feature article, some of the key challenges encountered and the adaptations employed to counter them are briefly reviewed. Copyright © 2014 John Wiley & Sons, Ltd.     

电喷雾电离质谱在化学中应用新进展

电喷雾电离质谱(ESI-MS)是本世纪发展的非常重要的质谱,具有无碎片的特点,可分析检测非挥发性的、极性的、热不稳定的化合物。评述了ESI-MS在富勒烯化学、无机配合物、簇合物、有机化学反应,金属有机化合物及超分子化学中的应用进展。     

ESI‐TOF mass spectrometry of cationic carbosilane dendrimers: A potent tool for characterization of structural defects

Macromolecular polyelectrolytes are gaining considerable attention for the application in medicine that implies their detailed characterization. We have successfully applied electrospray ionization mass spectrometry (ESI MS) to the analysis of defects in the structure of three generations of polycationic carbosilane dendrimers bearing series of quarternary phosphonium groups at their periphery. Besides expected defects caused by incomplete conversion of particular reaction steps during the synthesis of dendritic scaffold and subsequent peripheral functionalization, also, several products of side reactions were observed together with defects created in the course of measurement (particularly ion exchange products). Defective molecules can be to some extent separated by means of gel permeation chromatography that proves that they are not products of in source fragmentation processes. Within the reaction sequence used for the synthesis of dendrimers under study, hydrosilylation was the source of most defects; the effectivity of quarternization depends on the type of phosphine. Results confirm high sensitivity of ESI MS towards defects, stability of the carbosilane skeleton towards fragmentation under the conditions of ESI ionization, and capability to detect both lower‐ and higher‐molecular weight impurities arising from the synthetic sequence in the same m/z range as the target dendrimer, thus providing valuable view of the polydispersity.     

1-取代哌啶-4-酮肟醚的合成与杀菌活性测定

以取代苄胺或苯乙胺为起始原料, 依次经Michael 加成, Dieckmann缩合, 水解脱羧, 肟化和醚化等多步反应合成了11个未见文献报道的1-取代哌啶-4-酮肟醚5a～5k. 目标化合物的结构经元素分析, IR, 1H NMR和MS测定确证. 初步杀菌活性测试表明, 部分化合物有较好的杀菌活性.     

Identification of ilaprazole metabolites in human urine by HPLC‐ESI‐MS/MS and HPLC‐NMR experiments

Ilaprazole is a new proton pump inhibitor designed for the treatment of gastric ulcers, and limited data is available on the metabolism of the drug. In this article, the structural elucidation of urinary metabolites of ilaprazole in human was described by HPLC‐ESI‐MS/MS and stopped‐flow HPLC‐NMR experiments. Urinary samples were precipitated by sodium carbonate solution, and then extracted by liquid–liquid extraction after adding ammonium acetate buffer solution. The enriched sample was separated using a C₁₈ reversed‐phase column with the mobile phase composed of acetonitrile and 0.05 mol/L ammonium acetate buffer solution in a gradient solution, and then directly coupled to ESI‐MS/MS detection in an on‐line mode or ¹H‐NMR (500 MHz) spectroscopic detection in a stopped‐flow mode. As a result, four sulfide metabolites, ilaprazole sulfide (M1), 12‐hydroxy‐ilaprazole sulfide (M2), 11,12‐dihydroxy‐ilaprazole sulfide (M3) and ilaprazole sulfide A (M4), were identified by comparing their MS/MS and NMR data with those of the parent drug and available standard compounds. The main biotransformation reactions of ilaprazole were reduction and the aromatic hydroxylation of the parent drug and its relative metabolites. The result testified that HPLC‐ESI‐MS/MS and HPLC‐NMR could be widely applied in detection and identification of novel metabolites. Copyright © 2010 John Wiley & Sons, Ltd.     

Solution or Gas Phase? Oxidation and Radical Formation in Electrospray Ionization Mass Spectrometry (ESI MS)

The relationship between one‐electron (e^?) oxidation processes and the formation of radical cations of endogenous and exogenous compounds in vivo is of considerable interest. This paper reports on the experiments that allow FTICR mass spectrometric (MS) detection of ion signals that are consistent with the formation of radical cations of caffeine (CA) and theophylline (TP) during electrospray ionization (ESI) in ESI FTICR MS and in on‐line electrochemistry (EC)/ESI FTICR MS in positive mode. Significantly, the signals of the radicals of CA^?+ and TP^?+can be enhanced by simple modifications of the operating conditions in ESI MS, facilitating investigations of radical formation and related reactions.     

Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites in urine by LC‐MS after derivatization and its application for differentiation between positional isomers of prilocaine

The demand for clinical toxicology analytical methods for identifying drugs of abuse and medicinal drugs is steadily increasing. Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites by GC‐EI‐MS and LC‐ESI‐MS/MS is of great analytical challenge. These compounds exhibit only/mostly fragments/product ions representing the amine‐containing residue, while the aromatic amide moiety remains unidentified. This task becomes even more complicated when discrimination between positional isomers of such compounds is required. Here, we report the development of a derivatization procedure for the differentiation and structural elucidation of a mixture of local anesthetic drugs and their metabolites that possess tertiary and secondary amines in water and urine. A method based on two sequential “in‐vial” instantaneous derivatization processes at ambient temperature followed by LC‐ESI‐MS/MS analysis was developed. 2,2,2‐Trichloro‐1,1‐dimethylethyl chloroformate (TCDMECF) was utilized to selectively convert the secondary amines into their carbamate derivatives, followed by hydrogen peroxide addition to produce the corresponding tertiary amine oxides. The resulting derivatives exhibited rich fragmentation patterns, enabling improved structural elucidation of the original compounds. The developed method was successfully applied to the differentiation and structural elucidation of prilocaine and its four positional isomers, which all possess similar GC and LC retention times and four of them exhibit almost identical EI‐MS and ESI‐MS/MS spectra, enabling their structural elucidation in a single LC‐ESI‐MS/MS analysis. The developed technique is fast and simple and enables discrimination between isomers based on different diagnostic ions/fragmentation patterns.     

Re-examination of the anion derivatives of isoflavones by radical fragmentation in negative electrospray ionization tandem mass spectrometry: experimental and computational studies

This paper reports theoretical and experimental studies of gas‐phase fragmentation reactions of four naturally occurring isoflavones. The samples were analyzed in negative ion mode by direct infusion in ESI‐QqQ, ESI‐QqTOF and ESI‐Orbitrap systems. The MS/MS and MSⁿ spectra are in agreement with the fragmentation proposals and high‐resolution analyses have confirmed the formulae for each ion observed. As expected, compounds with methoxyl aromatic substitution have showed a radical elimination of ?CH₃ as the main fragmentation pathway. A second radical loss (?H) occurs as previously observed for compounds which exhibit a previous homolytic ?CH₃ cleavage (radical anion) and involves radical resonance to stabilize the anion formed. However, in this study we suggest another mechanism for the formation of the main ions, on the basis of the enthalpies for each species. Compounds without methoxy substituent dissociate at the highest energies and exhibit the deprotonated molecule as the most intense ion. Finally, energy‐resolved experiments were carried out to give more details about the gas‐phase dissociation reaction of the isoflavones and the results are in agreement with the theoretical approaches. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct characterization of iodine covalently bound to fulvic acids by electrospray mass spectrometry.

Numerous studies have demonstrated that humic substances (HS) react with iodine to form iodo derivatives and thereby can control the bioavailability of radioisotopes. Unfortunately, none of these studies have provided detailed insights into product compounds and so far, to our knowledge, the direct analysis of these species by electrospray ionization (ESI) mass spectrometry has not been explored. The reactivity of iodine with fulvic acids (FA) present in HS was investigated by means of ESI coupled with a quadrupole time-of-flight (Q-TOF) mass spectrometer. ESI spectra of solutions, that were indicated by MS/MS analysis to have formed iodinated species, apparently displayed singly charged ions corresponding in m/z to hypothesized species, viz., [RI - H](-), R = (substituted FA compound). MS/MS analysis based on the diagnostic fragment ions for FA compounds and their iodo derivatives suggests that FA undergo aromatic substitutions. Furthermore, significant differences in mass profiles are observed that presumably result from extended redox reactions. The ESI-MS technique opens up new opportunities to understand the scavenging properties of HS towards radionuclides and heavy metals for environmental studies.     

肟醚噻二唑硫醚化合物的合成及其抗肿瘤活性

将2-巯基-5-取代基-1,3,4-噻二唑经与β-氯苯丙酮取代、盐酸羟胺肟化和氯甲基噁二唑醚化,合成了6种3-(5-取代基-1,3,4-噻二唑-2-硫代基)-1-苯基丙酮-O-(5-苯基-1,3,4-噁二唑-2-甲基)肟醚化合物(4a~4f),用1H NMR、IR、MS和元素分析表征了其结构。 用MTT法测试了6种目标化合物对人黑色素瘤细胞株B16、人白血病细胞株HL60和人肝癌细胞株SMMC-7721的体外细胞毒活性。 测试结果表明,部分化合物对3种癌细胞具有潜在的体外生长抑制活性。