表面解吸常压化学电离质谱快速鉴别樟木制品

采用自行研制的表面解吸常压化学电离质谱(SDAPCI-MS),在无需样品预处理的情况下,对樟木制品及普通木材进行检测,在正离子模式及m/z 90～400范围内获得其化学指纹图谱,并通过主成分分析(PCA)方法对所获指纹谱图信息进行分析,进而对不同样品进行鉴别。结果表明,SDAPCI-MS能够对樟木表面多种特征化学成分(樟脑,香叶醇等)进行解吸电离,快速获得樟木的化学指纹谱图,并能够对目标组分做多级串联质谱鉴定。结合PCA方法,可对不同品质、不同种类的木材样品进行区分。结果表明,本方法灵敏度高,分析速度快(单个样品分析时间小于3 min),可望应用于珍贵木材快速无损分析及品质鉴定。     

表面解吸常压化学电离质谱快速鉴别硫磺熏蒸八角

采用自行研制的表面解吸常压化学电离质谱(DAPCI-MS),无需样品预处理,对硫磺熏蒸八角和未熏八角直接进行正、负离子模式检测,获得其化学指纹图谱,并通过主成分分析(PCA)及聚类分析(CA)方法对所获指纹谱图信息进行分析,进而对不同样品进行鉴别。结果表明,在正、负离子模式下,DAPCI-MS都可对八角表面多种特征化学成分进行分析,快速获得八角的化学指纹谱图,并能够对目标组分进行多级串联质谱鉴定,结合PCA及CA方法可对八角是否经硫磺熏蒸进行快速鉴别。本方法无需样品预处理,灵敏度高,分析速度快,无污染,可望应用于市场上硫熏制品的快速鉴别。     

表面解吸常压化学电离质谱法快速测定茶叶化学指纹图谱

表面解吸常压化学电离质谱;茶叶;指纹图谱;快速检测     

表面解吸常压化学电离质谱法快速判别樟树化学型

采用表面解吸常压化学电离质谱(SDAPCI-MS)技术直接对5种化学型的樟树叶粉末片剂进行分析,获得其化学指纹谱图信息.采用主成分分析(PCA)、聚类分析(CA)和反向传输人工神经网络(BP-ANN)对谱图信息进行分析,获得各化学型樟树叶粉末片剂的特征质谱信息,进而对不同化学型样品进行判别.结果表明,在正离子模式下,SDAPCI-MS能快速获取樟树的化学指纹谱图;PCA分析中的PC1,PC2和PC3贡献率分别为79.9%,12.9%和4.2%,共计97.0%.SDAPCI-MS结合CA和BP-ANN测试样本准确率均为100%,能够快速、有效地判别出樟树化学型.     

六味地黄丸的高效液相色谱/电喷雾电离-质谱分析

建立了高效液相色谱/电喷雾电离-质谱定性分析六味地黄丸的方法,通过2级质谱识别了其中的9种化学成分。色谱条件为:Zorbax SB-C18色谱柱;乙腈-水二元高压梯度洗脱;二极管阵列检测器,设定波长254 nm;流速1 mL/min。质谱条件为:Agilent离子阱质谱仪;电喷雾电离(ESI)离子源;负离子检出模式。结果表明,六味地黄丸的总离子流色谱图比紫外色谱图具有更强的特征性,以质谱作为检测器是一种很好的研究中药指纹图谱的方法。     

基于表面解吸常压化学电离质谱法快速评价咖啡种子活力

为快速、无损地区分不同活力的咖啡种子,采用自行研制的表面解吸常压化学电离质谱(DAPCI-MS),在无需样品预处理的前提下,获得咖啡种子表面的化学指纹图谱,并分别进行了主成分分析(PCA)、聚类分析(CA)和判别分析(DA),获得不同活力的咖啡种子样品的质谱信息特征.结果表明,在正离子模式下,DAPCI-MS结合多变量分析方法能有效区分不同活力的咖啡种子.PCA提取了3个主成分,累计贡献率达到92.2％;CA可以将相同活力的咖啡种子聚在一起,准确率为100％;DA对训练样本的回判正确率为100％,交叉验证分析成功率为100％,对外部验证样本进行DA,正确率95.7％.本方法具有无需样品预处理,分析速度快,灵敏度高,对种子无损伤等优点,能为其它种子活力测定提供参考.     

电喷雾解吸电离质谱快速测定吴茱萸中生物碱

生物碱是许多中草药的活性有效成分,其含量的多少和种类的差异是导致中草药品质差异的重要因素.本文利用电喷雾解吸电离质谱(DESI-MS)能够在不需要样品预处理的前提下进行复杂基体样品分析的特点,采用酸性甲醇-水混合溶液作为喷雾试剂,在优化了的实验条件下快速获得了吴茱萸的DESI-MS指纹谱图,然后利用串联质谱对其中有重要活性的5种生物碱进行了结构鉴定.实验表明,基于固体表面解吸电离质谱分析的方法不需要萃取-分离手续,单个样品测定时间不超过1.5 min,大幅度提高了分析速度,有望在药品品质的在线监测和工艺过程控制中发挥重要作用.     

嗜酸性氧化亚铁硫杆菌代谢产物的常压化学电离质谱分析

本研究以721矿和745矿嗜酸性氧化亚铁硫杆菌为研究对象,采用常压化学电离质谱直接分析其代谢产物,分别考察了顶空采样( Headspace sampling)、界面采样( Interface sampling)和中性解吸采样( Neutral desorption sampling)3种进样方式对电离效果的影响。在优化条件下,常压化学电离质谱对微生物纯菌种和混合菌种的代谢产物均具有良好的分析能力,可根据获得的代谢产物指纹谱图结合主成分分析( PCA)方法和聚类分析( CA)方法区分2个放射性强弱不同区域共4类嗜酸性微生物样品,并对主要胺类、酯类等代谢成分进行串联质谱鉴定,为耐辐射微生物的相关研究提供了一种可借鉴的分析方法。     

脐橙果皮的室温和热辅助表面解吸常压化学电离质谱的比较

以脐橙果皮为研究对象,比较了室温和热辅助表面解吸常压化学电离源(DAPCI)的解吸电离特性,结合串联质谱技术,对果皮中香气、糖、黄酮类等主要成分进行了鉴定,并通过主成分分析(PCA)方法对热辅助DAPCI-MS所获外果皮指纹谱图信息进行分析,进而区分了3个不同产地脐橙。 结果表明,室温DAPCI-MS对脐橙果皮中的香气成分具有较强的解吸电离能力,而热辅助DAPCI-MS则更适合于分析果皮中的黄酮类和糖类及其衍生物。 DAPCI-MS具有灵敏度高、分析速度快等特点,有望成为农产品品质快速检测与产地识别研究的新方法。     

表面解吸常压化学电离质谱法直接分析牙齿微区表面

采用纳升取样表面解吸常压化学电离质谱法(nano-SDAPCI-MS)结合主成分分析(PCA),建立了一种采用具有微米级针尖的金属取样针直接对龋齿不同部位取样并进行快速质谱分析的方法.数据分析结果表明,同一颗龋齿不同部位的质谱指纹谱图之间存在差异;在不需要样品预处理的前提下通过串联质谱快速测定了龋齿中的乳酸、丙酮酸、苯乙酸和丙酸等成分.采用PCA方法可较好地将龋齿病灶位置与邻近正常组织进行区分,也可对不同牙病及健康牙齿进行区分.本方法可方便地对牙齿进行直接微区分析,为鉴别牙齿疾病及观测治疗效果提供了一种快速、简单的方法,为生物体中微细部位的快速取样及直接质谱分析提供了一种可能的解决方案.     

表面解吸常压化学电离质谱直接测定香辛蔬菜化学指纹

采用表面解吸常压化学电离质谱技术在无需样品预处理的前提下,对香辛蔬菜如韭菜、洋葱和大蒜的挥发性成分进行了快速检测,并对部分成分进行了二级串联质谱分析。 结果表明,韭菜叶片挥发性主要成分为2-甲基-2-戊烯、二甲基硫代亚磺酸酯、甲基烯丙基硫代亚磺酸酯等,其中二甲基硫代亚磺酸酯和甲基烯丙基硫代亚磺酸酯产生较强的M+H2O·+信号。 未切开的洋葱鳞茎挥发性成分质谱信号较弱,质谱图中主要是一些电晕放电产生的初始离子信号。 切开后的洋葱鳞茎挥发性成分质谱信号明显增强,主要是丙烯基次磺酸、丙基烯丙基硫代亚磺酸酯和二丙基硫代亚磺酸酯。 大蒜鳞茎挥发性成分主要是二烯丙基硫代亚磺酸酯。 切开后的大蒜鳞茎挥发性成分主要是丙烯基次磺酸。 实验对韭菜的二甲基硫代亚磺酸酯和甲基烯丙基硫代亚磺酸酯、洋葱的丙烯基次磺酸、大蒜的二烯丙基硫代亚磺酸酯进行了二级串联质谱分析。 表面解吸常压化学电离质谱技术无需样品预处理,分析速度快且对样品不造成破坏。     

Structural analysis of lipid A from Escherichia coli O157:H7:K- using thin-layer chromatography and ion-trap mass spectrometry

Rapid separation and structural identification of lipid A from Escherichia coli were performed using thin-layer chromatography (TLC) and mass spectrometry (MS). After the resolved spot of the lipid A had been scraped from TLC plate, the sample was re-extracted from the removed powder with chloroform-methanol (2 : 1, v/v) and analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and electrospray ionization (ESI) ion-trap MS. For detailed structural characterization, multiple-stage mass analysis (MS(4)) of the major species in ESI-MS/MS provided important information about the series of fragment ions. The dominant fragment ions in each MS stage were produced from the loss of fatty acyl groups mainly driven by charge-remote processes, and this information about the fragment ions can be used to deduce the composition or the position of the fatty acid substituent in the lipid A. In contrast, MALDI-TOFMS indicated that fragmentation resulted from charge-driven processes. Molecular mass profiling and fragmentation analysis provides essential information for clarifying the detailed structure of the lipid A from E. coli O157:H7:K(-).     

成骨细胞膜色谱/超高效液相色谱-飞行时间质谱法快速筛选六味地黄汤抗骨质疏松活性成分

采用成骨细胞建立了细胞膜色谱/超高效液相色谱-飞行时间质谱（CMC/UPLC-TOF/MS）的分析方法。该法可快速筛选中药方剂六味地黄汤中潜在的抗骨质疏松活性成分，通过细胞试验和斑马鱼骨质疏松模型试验验证了筛选结果梓醇的体内外药效作用。以六味地黄汤水提物（90 g/L）为样品，通过CMC/UPLC-TOF/MS分析，快速鉴别细胞膜色谱柱保留成分群，高选择性获取六味地黄汤中16种潜在活性成分。该文以前沿色谱法分析梓醇、丹皮酚、齐墩果酸与细胞膜色谱固定相的亲和强度，选择亲和强度和含量较高的梓醇进行体内外药效验证，发现梓醇在对小鼠成骨细胞有显著促生长作用，能提高骨质疏松斑马鱼头部骨矿化面积。CMC/UPLC-TOF/MS筛选方法能在复杂中药方剂中快速得到抗骨质疏松活性成分，具有操作简便、快速、高效灵敏的优势。     

Distinguishing authentic and counterfeit banknotes by surface chemical composition determined using electrospray laser desorption ionization mass spectrometry

Electrospray laser desorption ionization mass spectrometry (ELDI/MS) was used to rapidly distinguish authentic banknotes from counterfeits of the US dollar and the New Taiwan dollar. The banknotes' surfaces were irradiated with a pulsed ultraviolet laser, after which the desorbed ink compounds entered an electrospray plume and formed ions via interactions with charged solvent species. Authentic banknotes were found to differ from their counterfeit equivalents in their surface chemical compositions. The detected chemical compounds included various polymers, plasticizers and inks; these results were comparable with those obtained using solvent extraction followed by electrospray ionization mass spectrometry analysis. Because of the high spatial resolution of the laser beam, ELDI/MS analysis resulted in minimal damage to the banknotes. Copyright © 2013 John Wiley & Sons, Ltd.     

High sequence-coverage detection of proteolytic peptides using a bis(terpyridine)ruthenium(II) complex

The use of a bis(terpyridine)ruthenium(ii) complex for peptide labeling (Ru-CO labeling) supplied high intensity peaks in mass spectrometry (MS) analysis that overcame the contribution of protonation or sodiated adduction to peptides. Ru-CO-labeled insulin A- and B-chains were detected simultaneously in comparable peak abundance by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The mass spectra of chymotryptic peptide fragments of Ru-CO-labeled insulin also simultaneously indicated both N-terminal fragment ions, and amino acid sequences were determined easily by matrix-assisted laser desorption/ionization post-source-decay (MALDI-PSD). The sensitivity of detecting Ru-CO-labeled peptide fragment ions was not dependent on the length or the sequences of the peptides. The Ru-CO labeling method was applied to tryptic myoglobin fragments. The method indicated that each fragment ion is detected nearly equal in abundance and enabled the desired fragment ions to be distinguished from matrix clusters or their in-source fragments in lower mass regions. The desired fragment ions can be found in the mass region higher than 670.70 (= Ru-CO). This method provided a high sequence coverage (96%) by peptide mass fingerprinting (PMF). Application of this method to a protein mixture (myoglobin, lysozyme and ubiquitin) successfully achieved high sequence-coverage characterization (>90%) of these proteins simultaneously.     

Desorption sonic spray ionization for (high) voltage-free ambient mass spectrometry

Sonic spray ionization is shown to create a supersonic cloud of charged droplets able to promote efficient desorption and ionization of drugs directly from the surfaces of commercial drug tablets at ambient conditions. Compared with desorption electrospray ionization (DESI), desorption sonic spray ionization (DeSSI) is advantageous since it uses neither heating nor high voltages at the spray capillary. DeSSI therefore provides a more friendly environment in which to perform ambient mass spectrometry (MS). DeSSI-MS is herein evaluated for the analysis of drug tablets, and found to be, in general, as sensitive as DESI-MS. The (high) voltage-free DeSSI method provides, however, cleaner mass spectra with less abundant solvent cluster ions and with enough abundant analyte signal for tandem mass spectrometry (MS/MS). These features may therefore facilitate the DeSSI-MS detection of low molar mass components or impurities, or both. The higher-velocity supersonic DeSSI spray also facilitates matrix penetration thus providing more homogenous sampling and longer lasting ion signals.     

Analysis of amphetamines and fentanyls by atmospheric pressure desorption/ionization on silicon mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry and its application to forensic analysis of drug seizures

The suitability of atmospheric pressure desorption/ionization on silicon mass spectrometry (AP-DIOS-MS) and matrix-assisted laser desorption ionization mass spectrometry (AP-MALDI-MS) for the identification of amphetamines and fentanyls in forensic samples was studied. With both ionization techniques, the mass spectra recorded showed abundant protonated molecules, and the background did not disturb the analysis. The use of tandem mass spectrometry (MS/MS) allowed unambiguous identification of the amphetamines and fentanyls. AP-DIOS-MS/MS and AP-MALDI-MS/MS were also successfully applied to the identification of authentic compounds from drug seizures. Common diluents and tablet materials did not disturb the analysis and compounds were unequivocally identified. The limits of detection (LODs) for amphetamines and fentanyls with AP-DIOS-MS/MS were 1-3 pmol, indicating excellent sensitivity of the method. The LODs with AP-MALDI-MS/MS were about 5-10 times higher.     

The nature of collision-induced dissociation processes of doubly protonated peptides: comparative study for the future use of matrix-assisted laser desorption/ionization on a hybrid quadrupole time-of-flight mass spectrometer in proteomics.

Comparative MS/MS studies of singly and doubly charged electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) precursor peptide ions are described. The spectra from these experiments have been evaluated with particular emphasis on the data quality for subsequent data processing and protein/amino acid sequence identification. It is shown that, once peptide ions are formed by ESI or MALDI, their charge state, as well as the collision energy, is the main parameter determining the quality of collision-induced dissociation (CID) MS/MS fragmentation spectra of a given peptide. CID-MS/MS spectra of singly charged peptides obtained on a hybrid quadrupole orthogonal time-of-flight mass spectrometer resemble very closely spectra obtained by matrix-assisted laser desorption/ionization post-source decay time-of-flight mass spectrometry (MALDI-PSD-TOFMS). On the other hand, comparison of CID-MS/MS spectra of either singly or doubly charged ion species shows no dependence on whether ions have been formed by ESI or MALDI. This observation confirms that, at the time of precursor ion selection, further mass analysis is effectively decoupled from the desorption/ionization event. Since MALDI ions are predominantly formed as singly charged species and ESI ions as doubly charged, the associated difference in the spectral quality of MS/MS spectra as described here imposes direct consequences on data processing, database searching using ion fragmentation data, and de novo sequencing when ionization techniques are changed.     

Quantitative and qualitative determination of Liuwei Dihuang tablets by HPLC-UV-MS-MS

A method is developed for the analysis of allantoin, gallic acid, dihydromelittoside, loganin, paeoniflorin, benzoylpaeoniflorin, and paeonol in Liuwei Dihuang tablets by high-performance liquid chromatography (HPLC)-UV-mass spectrometry (MS)-MS. Gradient elution with methanol-acetonitrile-water-formic acid solvent system is employed in the HPLC-electrospray ionization-MS study. The positive-ion ESI mode is suitable for these compounds. The peaks of gallic acid, loganin, dihydromelittoside, paeoniflorin, benzoylpaeoniflorin, and paeonol are identified by their mass spectra and the fragments of their MS-MS spectra. Allantoin, gallic acid, loganin, paeoniflorin, and paeonol are simultaneously determined by UV detection at 210 nm for quantitative purposes.     

Identification of mammalian cell lines using MALDI-TOF and LC-ESI-MS/MS mass spectrometry

Direct mass spectrometric analysis of complex biological samples is becoming an increasingly useful technique in the field of proteomics. Matrix-assisted laser desorption/ionization mass spectroscopy (MALDI-MS) is a rapid and sensitive analytical tool well suited for obtaining molecular weights of peptides and proteins from complex samples. Here, a fast and simple approach to cellular protein profiling is described in which mammalian cells are lysed directly in the MALDI matrix 2,5-dihydroxybenzoic acid (DHB) and mass analyzed using MALDI-time of flight (TOF). Using the unique MALDI mass spectral "fingerprint" generated in these analyses, it is possible to differentiate among several different mammalian cell lines. A number of techniques, including MALDI-post source decay (PSD), MALDI tandem time-of-flight (TOF-TOF), MALDI-Fourier transform ion cyclotron resonance (FTICR), and nanoflow liquid chromatography followed by electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS) were employed to attempt to identify the proteins represented in the MALDI spectra. Performing a tryptic digestion of the supernatant of the cells lysed in DHB with subsequent LC-ESI-MS/MS analysis was by far the most successful method to identify proteins.