GC-MS测定二氯甲烷溶液中的氯化苦及测定过程中产生的新生化合物

以GC—MS联用测定了二氯甲烷溶液中的氯化苦,并通过改变进样口温度和传输线温度研究温度变化对测定氯化苦的影响。当进样口温度高于200℃时,氯化苦会与二氯甲烷发生明显反应,形成新的产物。通过比较分别以氘代二氯甲烷和二氯甲烷做溶剂时所生成产物的GC—MS质谱图的不同,推测了反应产物的结构。并比较了正离子化学电离方式和负离子化学电离方式测定氯化苦的灵敏度。     

低碳醣的解吸化学电离(DCI)质谱

本文首次报道了一系列低碳醣以甲烷作反应气的正和负离子解吸化学电离质谱。考察和讨论了其质谱特征,碎裂规律和分子离子反应。指出负离子解吸化学电离质谱对鉴别低碳醣的分子离子可以提供十分有用的信息。     

血卟啉及其金属衍生物的化学电离质谱

本研究采用直接曝热技术，分别以氢气和甲烷为反应气，测定了１０个血卟啉衍生物和１３个金属血卟啉衍生物的正、负离子解吸化学电离质谱，探讨了各种化学电离质谱法在结构测定中的应用。     

简单高效制备甲烷气体的方法

乙酸钠、氢氧化钠、氧化钙研磨混合法制备甲烷气体的实验存在反应速率慢、产率低、试管易破裂及不易清洗等问题。基于此,在反应物不变的情况下,采用溶剂混合法,可实现快速、高效制备甲烷气体,同时也解决了试管破裂、不易清洗等问题。该方法解决了以往制备甲烷气体的不足,可有效应用于化学实验中。     

气相色谱-附加氯的化学电离与低分辨质谱法联用测定短链氯化石蜡含量

以己烷-二氯甲烷混合溶剂上气体经石英毛细管柱直接导入离子源为反应气,建立了气相色谱-附加氯的化学电离-低分辨质谱法检测短链氯化石蜡。加标回收率在84.9%~95.4%之间,测定值的相对标准偏差在15%~18%之间。本法应用于实际样品测试,并和碳骨架法进行了对比。结果表明:对于中链(MCCP)与短链的氯化石蜡(SCCP)质量比(mMCCP/mSCCP)比值较低样品,相对误差在3.67%~7.69%之间;对于mMCCP/mSCCP比值较高样品,相对误差为77.9%。     

气相中甲苯离子-分子反应产物的串联质谱研究

应用碰撞诱导解离技术, 研究了甲苯自身化学电离条件下离子-分子反应产物离子m/z 182和184的碰撞诱导解离(CID)反应特性。m/z183和184离子碎裂反应具有多种过渡态结构, 如二苯基甲烷衍生物结构、卓翁离子与甲苯形成的共价键结构、甲苯自由基离子与甲苯分子形成的π-配合物结构和苄基离子与甲苯形成的π-配合物结构。     

甲醇和乙醇在氩气-实时直接分析质谱中的应用

以氩气代替价格昂贵的氦气作为实时直接分析质谱(DART-MS)的工作气体以降低实验成本。甲醇和乙醇作为作为两种辅助性反应试剂,在Ar-DART-MS分析中充当能量传递的媒介和质子的供体,可以提高Ar-DART-MS的电离效率并扩展其应用范围。通过甲醇和乙醇作为反应性试剂在Ar-DART-MS的背景信号及对样品电离影响的分析,探讨了它们的应用范围,以及在电离过程中存在的一些可能的特征反应。该方法的有效性通过对利血平的分析结果获得。     

若干糖苷类化合物的负离子化学电离质谱研究

本文报道苦玄参苷类(picfeltarraenins)(1～5)、膜荚黄芪苷类(astramembrannins)(6～8)、雪胆素苷类(hemsamabilinins)(9,10)及其O-乙酰衍生物(11,12)和洋地黄毒苷(digitoxin)(13)的负离子化学电离质谱.用甲烷和二氯甲烷作为混合反应气,获得了满意的结果.谱中有特征的M~(?)或[M-1]~-,[M+Cl]~-和一系列脱糖基的碎片离子[M+Cl-nR]~-(R为不同类型的糖基)及糖基碎片离子[R+Cl]~-.乙酰化的糖苷还给出[M+Cl-nCH_2CO]~-或[M+Cl-nCH_3COOH]~-等碎片离子.     

通过碰撞使甲烷转换成汽油

将甲烷(天然气的主要成分)转换成组成汽油的较大碳氢化合物分子的流程加以简化将为全球提供取之不尽的运输燃料。阿拉斯加大学地球物理学家兼电气工程师William Sackinger 等最近获得“用于变换分子量的电器件”的专利权。用这种设备能将小的碳氢化合物分子变成较大者。在实验原型中,他和同事们将甲烷泵入由6百万只细小的玻璃反应管组成的反应器中,用电场对气体分子进行电离和加速,使它们同吸附在玻管上的其它碳氢化合物分子相撞并结合在一起。目前     

超高交联树脂吸附二氯甲烷蒸气的平衡和动力学特性及应用

开展了超高交联吸附树脂对气体中二氯甲烷的静态吸附行为研究,分别采用Langmuir、Freundlich和Dubinin-Astakov模型方程对吸附平衡数据进行拟合分析,拟合结果表明,Dubinin-Astakov方程能较好地拟合吸附平衡数据,表明在吸附过程中微孔填充起着很重要的作用;采用固定床吸附工艺研究了二氯甲烷在树脂上的动态吸附行为,用Yoon-Nelson模型对穿透曲线进行拟合,实验数据与模拟值吻合良好。在实验研究的基础上开发了二氯甲烷废气超高交联树脂吸附回收工艺并建立工业化装置,处理效果良好、运行稳定。     

Detection of chlordanes by positive ion chemical ionization in an ion trap: a comparative [correction of comparitive] study of the non-conventional reagents acetonitrile, acrylonitrile and dichloromethane

The detection of some chlordane compounds (heptachlor, cis-/trans-chlordane and cis-/trans-nonachlor) by positive ion chemical ionization (PICI) in an ion trap was studied using acetonitrile, acrylonitrile and dichloromethane as non-conventional reagent gases. These reagent gases initiated specific fragmentation reactions and resulted in different response factors. All reagent gases enabled detection limits in the low-pg range for heptachlor, whereas the detection limits of cis-/trans-chlordane and cis-/trans-nonachlor were in the mid-pg range. Additionally, the acetonitrile and dichloromethane PICI mass spectra of the cis- and trans-stereoisomers of chlordane and nonachlor were different.     

Improving quantitative gas chromatography-electron ionization mass spectrometry results using a modified ion source: demonstration for a pharmaceutical application

Gas chromatography-mass spectrometry is a well established analytical technique. However, mass spectrometers with electron ionization sources may suffer from signal drifts, hereby negatively influencing quantitative performance. To demonstrate this phenomenon for a real application, a static headspace-gas chromatography method in combination with electron ionization-quadrupole mass spectrometry was optimized for the determination of residual dichloromethane in coronary stent coatings. Validating the method, the quantitative performance of an original stainless steel ion source was compared to that of a modified ion source. Ion source modification included the application of a gold coating on the repeller and exit plate. Several validation aspects such as limit of detection, limit of quantification, linearity and precision were evaluated using both ion sources. It was found that, as expected, the stainless steel ion source suffered from signal drift. As a consequence, non-linearity and high RSD values for repeated analyses were obtained. An additional experiment was performed to check whether an internal standard compound would lead to better results. It was found that the signal drift patterns of the analyte and internal standard were different, consequently leading to high RSD values for the response factor. With the modified ion source however, a more stable signal was observed resulting in acceptable linearity and precision. Moreover, it was also found that sensitivity improved compared to the stainless steel ion source. Finally, the optimized method with the modified ion source was applied to determine residual dichloromethane in the coating of coronary stents. The solvent was detected but found to be below the limit of quantification.     

Enantiomeric Separation of Amino Alcohols by Ion-pair Chromatography

Many drugs or physiologically important compounds are chiral molecules and the optical isomers of them may differ in their pharmacological activities. In some instances differences in undesirable side-effects of these enantiomers are important. So the separation of chiral compounds is becoming increasingly important. Liquid chromatography (LC) is well known as an excellent method for separating and analyzing mixtures of stereoisomers. For resolving the ionic chiral compounds it is available t…     

Optimisation of piezoelectric injection of dopants and drift gas modifiers in transverse ion mobility spectrometry

Novel experimental methods are described for controlling the levels of dopant or drift gas modifier with piezoelectric actuation. The piezoelectric jetting of 2-butanol, acetone, 4-heptanone and dichloromethane was first optimised by applying a fractional factorial experimental design to the waveform required to actuate the dopants. The concentration of dopant entering a transverse ion mobility cell was dynamically controlled by a series of air flows at the interface between the actuator and the ion source, as well as the droplet injection frequency, as defined by the optimised waveform parameters. The optimisation methodology indicated that dwell time and dwell voltage were the most important factors in controlling the process. The optimised approach was then used to deliver varying levels of candidate dopants; 20.5 to 196.6 μg?m^?3 for 2-butanol, 35.4 to 164.3 μg?m^?3 for acetone, 17.8 to 58.2 μg?m^?3 for 4-heptanone and 27.6 to 270.2 μg?m^?3 for dichloromethane. The method enables reactant ion chemistry to be switched in the order of 3 to 5 sec, indicating the potential for introducing multiple dopants at varying concentrations into ion mobility spectrometers. The most volatile material dichloromethane was more difficult to control and the reproducibility and stability of the instrument responses to this compound was not as good as the other less volatile ones. The concept of extending this approach to mixtures and dual use formulations, doping and modification was proposed.     

Iron Perchlorate on Silica Gel as Multi-purpose Reagent for Catalysis of Closure and Rupture of Carbon-Oxygen Bond in Epoxides,Alcohols, and Esters

Aliphatic alcohols and water in the presence of catalytic amounts of Fe³⁺ ion introduced as acids esterification with various type alcohols was carried out using the system Fe(ClO₄)₃-silica gel in dichloromethane under conditions excluding solvolysis. Acetylation and formylation of alcohols was performed by efficient transesterification with ethyl acetate and ethyl formate.     

Chiral separation of amines with N-benzoxycarbonylglycyl-L-proline as selector in non-aqueous capillary electrophoresis using methanol and 1,2-dichloroethane in the background electrolyte

N-Benzoxycarbonylglycyl-L-proline (L-ZGP) has been introduced as a chiral selector for enantioseparation of amines in non-aqueous capillary electrophoresis. Methanol mixed with different proportions of dichloromethane, 1,2-dichloroethane or 2-propanol containing L-ZGP and ammonium acetate was used as the background electrolyte. Enantioseparation of different types of pharmacologically active amines was performed, e.g. the local anaesthetic bupivacaine and the beta-adrenoceptor blocking agent pindolol. Addition of the solvents (dichloromethane, 1,2-dichloroethane or 2-propanol) gave an improved chiral separation partly due to a distinct decrease in the electroosmotic flow. The use of 1,2-dichloroethane in the background electrolyte gave higher precision in migration time (RSD 2.2%) compared to the systems containing dichloromethane. An enantiomeric separation of mepivacaine was performed within 72 s by use of short-end injection with an effective capillary length of 8.5 cm.     

Cationic and anionic fragmentation of dichloromethane following inner-shell (Cl 1s) photoexcitation

The cationic and anionic fragmentation of dichloromethane (CH2Cl2) molecule have been investigated in the energy range of the Cl K shell by using synchrotron radiation, ion yield spectroscopy, and electron-ion coincidence spectroscopy. Total and partial ion-yield and mass spectra have been recorded as a function of the photon energy. We were able to identify several singly and multiply charged cationic fragments and the following anionic species: H-; C-; Cl-. The present results provide the first experimental report of negative ion formation from a molecule excited at the Cl 1s edge. In addition, our electron-ion coincidence data provide strong evidence of the preservation of molecular alignment for the photodissociation of CH2Cl2 after deep core-electron resonant excitation.     

Ion aggregation of methylpyrazinium iodide and its derivatives in crystals and in solutions of nonpolar solvents

Aggregation of methylpyrazinium iodide and its derivatives in chloroform and dichloromethane solutions was studied by EAS and ¹H NMR spectroscopy. The isopentylpyrazinium iodide ion quadruple formation constants in solutions were evaluated. Formal extinction coefficient in the outer-sphere charge transfer band maxima does not depend on the degree of aggregation in the system. A model suggested for the formation of ion quadruples in solutions was discussed in terms of the density functional theory and using the X-ray diffraction data for crystalline methylpyrazinium iodides and its derivatives.     

流动注射纳米微反应器化学发光法测定盐酸阿米替林

在酸性条件下,盐酸阿米替林分子中氮原子被质子化后与阴离子AuCl4-形成离子缔合物,该缔合物被二氯甲烷带入鲁米诺的氯化十六烷基三甲基铵反胶束纳米微反应器中,离解出来的AuCl4-立即与鲁米诺产生化学发光.在一定浓度范围内,发光强度与盐酸阿米替林的含量成线性关系,从而间接测定盐酸阿米替林的含量.在优化的实验条件下,线性范...     

Method for the analysis in maize of the Fusarium mycotoxin moniliformin employing ion-pairing extraction and high-performance liquid chromatography

The Fusarium mycotoxin moniliformin (hydroxycyclobutenedione) has been determined in maize using a novel method with a recovery of 70-80% at 400-1600 micrograms/kg and 60% at the detection limit of 100 micrograms/kg. The method requires extraction of the toxin into aqueous tetra-n-butylammonium hydroxide and removal of cations from this solution by ion-exchange chromatography. Following clean-up by partitioning against dichloromethane, further quaternary ammonium reagent was added to the aqueous phase which was absorbed onto a hydrophilic matrix and the tetra-n-butylammonium moniliformate ion pair extracted into dichloromethane. After evaporation of the organic eluent, the residue was dissolved in aqueous sodium chloride and moniliformin quantitated by ion-pair high-performance liquid chromatography with UV detection. A batch of five samples may be analysed in 5-6 h including the chromatographic determination.