岩石抽提物中极性化合物超高分辨质谱识别

采用具有超高分辨率的负离子电喷雾-傅立叶变换离子回旋共振质谱（ESI FT-ICR MS）分析了储层岩石抽提物中的石油酸及中性氮化物的分子组成,得到了抽提物中杂原子化合物类型分布、等效双键数（Double bonds equivalent,DBE）及碳数分布特征。研究结果表明,储层抽提物中含有多达16种不同杂原子类型的化合物,包括N1、N1O1、N1O2、N1O3、N1S1、N1S2、N2、N2S1、O1、O1S1、O2、O2S1、O1S2、O2S2、O3和O4,其中N1、N1S1、O2及O2S1类具有较高的相对丰度。抽提物中的N1类化合物以咔唑和苯并咔唑类化合物为主;N1S1类化合物以C2~C8烷基取代的咔唑并苯并噻吩类化合物为主;O2类化合物主要为1~2环环烷酸,其次还在抽提物中鉴别出具有较高相对丰度的DBE为5和6的O2类化合物;而O2S1类化合物中以DBE为7和8的O2S1具有最高的相对丰度。     

渤海稠油及其组分中杂原子化合物的负离子电喷雾-高分辨质谱分析

采用沉淀法和色谱分离法将渤海某油田稠油分离成沥青质、胶质、剩余分3个组分。采用负离子电喷雾技术(ESI)结合高分辨傅立叶变换离子回旋共振质谱仪(FT-ICR MS)研究了该稠油及各组分的分子组成。结果表明,剩余分中有较少的极性杂原子化合物能被负离子ESI电离,如N_1,N_1O_1,O_1和O_2类,其等效双键数(DBE)较小。胶质和原油中极性化合物有相同的杂原子类型,包括N_1,N_1O_1,N_1O_2,N_2,N_2O_2S_1,O_1,O_2,其中胶质和原油中N_1,O_1,O_2类化合物的DBE-碳数分布图相似。沥青质中富集高缩合度且多杂原子的酸性化合物,如含杂原子N_,S的氧化程度高的化合物(N_2O_1,N_1O_3,S_1O_3)及O_3类化合物,这些物质具有较高的界面活性,易吸附在界面上促进界面张力降低和增强界面膜强度,从而有利于乳状液稳定存在。N_1O_1,N_1O_2,N_1O_3类化合物,N_2O_1类化合物可能分别是N_1化合物,N_2化合物的氧化降解产物;随着氧化降解程度增加,降解产物的极性明显增强。     

基于FT-ICR质谱仪的光解离光谱自动化谱图采集程序的开发与应用

光解离光谱在气相离子结构及动力学研究中发挥着重要的作用。这种方法非常灵活,可在实验室中利用不同种类的激光器及质谱仪的结合来开展相应的研究。但也存在一些问题,例如,自动化水平低,费时,长时间的操作容易引入人为错误,使实验结果的可信度降低。为解决此类问题,该工作开发了一套可用于光谱自动采集和分析的程序AutoMS。该程序包含：(1)AutoSpecMS用于在无需改变原仪器配套的商业化操作软件的前提下,实现多台商业激光器及一台商业高分辨FT-ICR质谱仪的集成,只需要预设参数即可自动获取action光谱;(2)AutoDataMS用于实验数据的分析,可以通过一维、二维或三维图示的方法来展示光解离质谱和光谱等。为验证改程序的可行性,针对tetraphenylpyrrin(四苯基卟啉,TPP),tetra(4-carboxypyryl)porphyrin(四对羧基苯基卟啉,TCPP)以及tetra(4-aminophenyl)porphyrin(四对氨基苯基卟啉,TCPP)三种卟啉衍生物分别开展了相应的实验。使用光解离光谱自动采集程序采集了TPP, TCPP和TAPP在210~700 nm波段的紫外-可见光解离光谱。同时获得了相关光解离碎片离子的单通道光谱,有利于用户对所研究体系的解离机理及解离动力学等方面开展深入的分析探讨。光解离质谱可观察到目标离子在特定波长激光照射下的具体解离碎片,与光解离光谱相结合,可以更好地帮助研究者理解离子在特定波段内的光解离行为。使用AutoDataMS可分别获得样品的2D及3D光解离质谱-光谱,增强了结果的可视化,使研究者更方便地获得光谱中的相关信息。对数据进行进一步分析可看出,不同的取代基对紫外可见光谱的吸收产生了差异明显的影响。此外通过AutoDataMS程序的功能扩展,还实现了对质子化TPP在500～650 nm波段内各离子的相关度分析,加深了对实验数据的理解。由此可见该方法及程序具有较好的扩展性和实用性,并可以为其他相关的工作提供很好的参考。     

Characterization of nucleic acid higher order structure by high-resolution tandem mass spectrometry

Mass spectrometry (MS) is extensively used for the identification and sequencing of nucleic acids but has so far seen limited use for characterization of their higher order structures. Here, we have applied a range of different tandem mass spectrometry techniques, including electron detachment dissociation (EDD), infrared multiphoton dissociation (IRMPD), activated ion (AI) EDD, and EDD/IRMPD MS³, in a Fourier transform ion cyclotron resonance mass spectrometer to the characterization of three isomeric 15mer DNAs with different sequences and predicted solution-phase structures. Our goal was to explore whether their structural differences could be directly probed with these techniques. We found that all three 15mers had higher order structures in the gas phase, although preferred structures were predicted for only two of them in solution. Nevertheless, EDD, AI EDD, and EDD/IRMPD MS³ experiments yielded different cleavage patterns with less backbone fragmentation for the more stable solution-phase structure than for the other two 15mers. By contrast, no major differences were observed in IRMPD, although the extent of backbone cleavage was higher with that technique for all three 15mers. Thus, experiments utilizing the radical ion chemistry of EDD can provide complementary structural information compared to traditional slow heating methods, such as IRMPD, for structured nucleic acids.     

Metabolomic Profiling of Fresh Goji (Lycium barbarum L.) Berries from Two Cultivars Grown in Central Italy: A Multi-Methodological Approach

The metabolite profile of fresh Goji berries from two cultivars, namely Big Lifeberry (BL) and Sweet Lifeberry (SL), grown in the Lazio region (Central Italy) and harvested at two different periods, August and October, corresponding at the beginning and the end of the maturation, was characterized by means of nuclear magnetic resonance (NMR) and electrospray ionization Fourier transform ion cyclotron resonance (ESI FT-ICR MS) methodologies. Several classes of compounds such as sugars, amino acids, organic acids, fatty acids, polyphenols, and terpenes were identified and quantified in hydroalcoholic and organic Bligh-Dyer extracts. Sweet Lifeberry extracts were characterized by a higher content of sucrose with respect to the Big Lifeberry ones and high levels of amino acids (glycine, betaine, proline) were observed in SL berries harvested in October. Spectrophotometric analysis of chlorophylls and total carotenoids was also carried out, showing a decrease of carotenoids during the time. These results can be useful not only to valorize local products but also to suggest the best harvesting period to obtain a product with a chemical composition suitable for specific industrial use. Finally, preliminary studies regarding both the chemical characterization of Goji leaves generally considered a waste product, and the biological activity of Big Lifeberry berries extracts was also investigated. Goji leaves showed a chemical profile rich in healthy compounds (polyphenols, flavonoids, etc.) confirming their promising use in the supplements/nutraceutical/cosmetic field. MG63 cells treated with Big Lifeberry berries extracts showed a decrease of iNOS, COX-2, IL-6, and IL-8 expression indicating their significant biological activity.     

Prospects of Ion Chemical Reactions with Heavy Elements in the Gas Phase

Heavy element chemistry is related to the fundamental interest that lies in exploring the upper limits of the periodic table. Chemical properties of the heaviest elements have already been studied at single atoms in aqueous solutions and in the gas phase up to an atomic number Z = 107. These techniques allow to study nuclides with half lives as short as about 1 s. Next generation chemistry experiments could be envisaged with an ion trap technique already developed for stable isotopes. At very low production rates in the order of 1 per 100 s and/or half lives as short as about 10 ms, the ion-molecule reactions can be studied in a buffer gas cell, in which the heavy elements are stopped and thermalize with a high probability as singly charged ions. Ion-molecule reactions with well defined buffer gas admixtures, as, e.g., O₂, H₂O, CH₄, CO₂, are identified by mass selective detection. This revised version was published online in July 2006 with corrections to the Cover Date.     

双光束光解离在牛泛素蛋白离子的自顶向下质谱分析中的应用研究

自顶向下(Top-down)质谱分析方法是将完整蛋白质离子碎片化,从而在分子水平上提供更加精准、丰富的与蛋白质结构相关的生物学信息.该文首次将3μm红外激光与210 nm紫外激光共同引入到傅里叶变换离子回旋共振质谱仪(FT-ICR MS)的分析池中,获得了牛泛素蛋白离子的自顶向下质谱.通过优化两束激光被引入的时间序列,...     

石油芳烃组分中未知化合物——三叔丁基苯基磷酸酯的高分辨质谱分析

将大气压光电离(APPI)、电喷雾(ESI)、实时直接分析(DART)多种电离源和傅立叶变换离子回旋共振质谱(FT-ICR MS)联用对石油芳烃样品中的未知化合物进行研究。通过高分辨质谱的精确质量,结合碰撞诱导解离(CAD)技术,经分析并与文献标准物质谱图比对,推断未知物为三(2,4-二-叔丁基苯基)磷酸酯(TDTBPP),并研究了其在不同大气压电离源中的电离特性。APPI谱图中主要为[M+H]~+峰,同时存在M.~+峰。ESI谱图中主要为[M+Na]~+(不加甲酸)或[M+NH4]~+峰(加甲酸)。DART谱图中主要为[M+NH4]~+峰,而EI谱图中基峰为m/z 57(叔丁基),次强峰为[M-CH3]~+峰。     

A Comparative Study of Pyrolysis Liquids by Slow Pyrolysis of Industrial Hemp Leaves,Hurds and Roots

This study assessed the pyrolysis liquids obtained by slow pyrolysis of industrial hemp leaves, hurds, and roots. The liquids recovered between a pyrolysis temperature of 275–350 °C, at two condensation temperatures 130 °C and 70 °C, were analyzed. Aqueous and bio-oil pyrolysis liquids were produced and analyzed by proton nuclear magnetic resonance (NMR), gas chromatography–mass spectrometry (GC-MS), and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). NMR revealed quantitative concentrations of the most abundant compounds in the aqueous fractions and compound groups in the oily fractions. In the aqueous fractions, the concentration range of acetic acid was 50–241 gL⁻¹, methanol 2–30 gL⁻¹, propanoic acid 5–20 gL⁻¹, and 1-hydroxybutan-2-one 2 gL⁻¹. GC-MS was used to compare the compositions of the volatile compounds and APPI FT-ICR MS was utilized to determine the most abundant higher molecular weight compounds. The different obtained pyrolysis liquids (aqueous and oily) had various volatile and nonvolatile compounds such as acetic acid, 2,6-dimethoxyphenol, 2-methoxyphenol, and cannabidiol. This study provides a detailed understanding of the chemical composition of pyrolysis liquids from different parts of the industrial hemp plant and assesses their possible economic potential.