顶空-气相色谱-质谱联用分析桂花和叶中挥发性成分

采用谱库检索结合准确质量测定、保留指数、串联质谱技术的多维定性分析策略鉴定化合物, 能够提高定性分析的效率和准确性. 运用顶空-气相色谱-四极质谱、顶空-气相色谱-飞行时间质谱以及顶空-气相色谱-串联质谱联用技术对桂花样品进行了分析检测, 并采用多维定性分析思路对检出的挥发性成分进行了鉴定. 结果共确认出47种挥发性成分, 其中单萜类和倍半萜类化合物为主要组分. 该定性分析策略准确可靠, 可以广泛应用于复杂样品挥发性成分的定性分析中.     

基于准确质量测定和保留指数的GC-MS分析薄荷挥发性成分

采用顶空-气相色谱-四极质谱法和顶空-气相色谱-飞行时间质谱法对薄荷挥发性成分进行了检测, 分别从薄荷茎和叶中鉴定出39种和64种挥发性组分, 其中以酮类和萜烯类化合物为主. 本定性分析策略在复杂样品挥发性成分的定性分析中具有良好的应用前景.     

电喷雾-飞行时间质谱测定氨基醇类化合物及衍生物的准确质量

本文应用聚乙二醇400(PEG400)作内标,通过电喷雾-飞行时间质谱测定5个氨基醇类化合物及衍生物的准确质量,并考察了锥孔电压、锥孔温度等因素对准确质量测定的影响.     

液相色谱-大气压化学电离飞行时间质谱分析氢化可的松中微量杂质

大气压化学电离是1种较软的离子化方法,溶剂在雾化气及加热的作用下雾化,并迅速汽化.在大气压状态的区域内,汽化的分子在高电压条件下相互间发生碰撞及电荷转移,形成等离子体.样品分子M通过这一区域时与其反应,从而实现离子化,产生[M+H]+或[M-H]-准分子离子.为了进一步了解样品分子结构,采用源内碰撞诱导的技术即在离子源内增加喷口的电压,使分子离子碰撞裂解产生碎片离子.综合检测到的准分子离子和碎片离子信息,可更多地了解所测分子的结构信息.氢化可的松为肾上腺皮质激素类药物,有抗炎和抗风湿作用,亦称抗炎激素.在药品生产过程中,由于原料、副反应等因素引入了一些杂质.液质联用的方法可以简单、快速地提供这些杂质的分子信息.     

电喷雾质谱法研究细胞色素Tb5及其F35Y突变体蛋白肽链和辅基的相互作用

本文通过牛肝线粒体细胞色素Tb5和它的F35Y突变体蛋白相对分子质量的外标法测定,得到细胞色素Tb5全蛋白的相对分子质量为10077.5脱辅基蛋白的相对分子质量为9461.4F35Y突变体蛋白的相对分子质量为10093.6,它的脱辅基蛋白的相对分子质量为9477.5,不同nozzle电压下的电喷雾质谱结果表明,该电压的大小明显影响蛋白肽链与血红素辅基之间的非共价结合,随着电压的降低,全蛋白谱峰的强度逐渐增大,然而,过低的电压导致了Na^+,K^+离子加合峰相对强度的增加,而不利于谱图分析。同时,考察到细胞色素Tb5在甲醇溶液和酸性溶液中的变性行为,因此选择nozzle电压70V,10%的甲醇水溶液和pH=7为得到全蛋白质谱峰的最佳条件。相同实验条件下得到的野生型CytTb5和F35Y突变体全蛋白的质谱峰相比较,其相对丰度有悬殊的差异,表明F35Y突变体蛋白的血红素结合能力明显低于野生型蛋白。通过解离出的Hemeb的分子离子峰进行解析,证明铁仍以三价离子存在于血红素辅基中。     

顶空-固相微萃取-毛细管气相色谱-质谱联用方法快速分析香精中挥发性化学成分

通过在香精样品中加入饱和NaCl溶液,建立了适合香精样品直接自动化分析的顶空一固相微萃取一毛细管气相色谱-质谱联用分析方法。采用保留指数检索对质谱检索结果进行进一步的确认,以提高对挥发性成分定性分析的准确性。结果表明：香精中主要含有茴香脑(42．4％)、丁子香烯(5．5％)和β-石竹烯(4．3％)。该方法的精密度为4．0％～8．9％。     

Exact Mass Measurements for a-Allenic Alcohol by Atmospheric Pressure Chemical Ionization／Time-of-flight Mass Spectrometry

The atmospheric pressure chemical ionization/time,of-flight mass speetrmtry (APEI/TOF-MS) was applied to determine the mass of five a.aIIenic alcohols via their vrotonated molecu.lar ions nslna Imsifive ion mode. Polyethylene Idycol (PEG) was used as the hlternal reference. All results were obtained under the resolution of about 5000 FWHM (full width at the half maximum). Solvent effects were studied and the satired results were obtained in acetonitrile. Comvared with the theoreflcal values, nun absolute errors were less thRn 1.0 mmu. The efTeets Of nozzle pote.Jldal, push pulse potential, pug pulse potentlai, puO bias potential and ic(lulsltion rate on exact mass determina/lon were also discussed. APCI/TOF.MS is proven to be a very semi/ire analytical technique and an alternative ionizafion mode in analytical technique lablle compounds with relatively weak polarity, such as a-allenic alcohol.     

GC/MS中保留指数和保留温度回归分析应用于单萜烯结构确认

GC／MS定性分析中,由于同分异构体的质谱图相似,常常出现结构鉴定错误．同分异构体化合物的保留行为具有较大地差别,采用文献保留指数和保留温度测定值回归分析方法对2篇已发表论文进行了研究,发现了对单萜烯类同分异构体结构鉴定中存在的错误,并提出可能的正确结构．文献保留指数和保留温度测定值回归分析方法可以简化GC／MS色谱峰的定性分析过程,提高定性分析的准确性,在样品定性分析中具很强的使用价值．     

Comparative Analysis of the Volatile Components in the Fresh Roots and Rhizomes of Curcuma wenyujin by Static Headspace Gas Chromatography Mass Spectrometry

Static headspace GC-MS method coupled with H/D exchange was firstly developed to determine and identifythe volatile components in the fresh root and rhizome of Curcuma wenyujin.The TIC chromatograms of 3 batchesof fresh roots harvested at different time showed significant difference in the volatile components:the constitutionwas the same but the content of them was different.More than 60 volatile components in fresh roots(Root of C.wenyujin)and rhizomes(Rhizome of C.wenyujin)of C.wenyujin were detected,of which 51 and 48 volatile com-ponents were identified respectively.The fresh roots and rhizomes of C.wenyujin were found to have the similarvolatile components.The contents of these components were calibrated by the response of β-elemene.In addition,the principal active component,β-elemene,was further confirmed and relatively quantified by its standard.γ-terpinene showed obvious allylic hydrogen/deuterium exchange using deuterium oxide which gave a new methodto identify some compounds containing allylic hydrogen.At the same time,the active hydrogen compounds werealso further confirmed.The results show that HS-GC-MS method is a fast,simple and efficient way for the analysisof volatile components from medical plants.     

Detection of Radical Adducts with Small Molecular Weights by Matrix-Assisted Laser Desorption/Ionization with Fourier Transform Mass Spectrometry

As an alternative method, matrix-assisted laser desorption/ionization with Fourier transform mass spectrometry （MALDI-FTMS） has been successfully used to detect and identify free radical adducts with small molecular weights of hydroxyl and 2-cyano-2-propyl radicals trapped with 5,5-dimethylpyrroline N-oxide （DMPO）. The detection and identification by MS/MS experiments using sustained offresonance irradiation collision-induced dissociation （SORI-CID） of [（DMPO＋·OH-·H）＋H^＋] （m/z 130.0868） and [DMPO＋2 ·CH（CH3）2CN＋H^＋] （m/z 250.1917） have demonstrated that MALDI-FTMS could be an effective method for detection and identification of free radical adducts. Other radical adducts have been also detected and identified. The approach of MALDI-FTMS is simple, fast, and sensitive which has potential for high-throughput analysis.