MALDI-TOF MS characterization of polystyrene synthesized by ATRP

In this work, we investigated the peculiar peaks found in the MALDI-TOF mass spectra of polystyrenes (PS) with a bromine end prepared by atom transfer radical polymerization when silver trifluoroacetate (AgTFA) and THF were used as cationization agent and solvent, respectively, in the MALDI sample preparation. In the MALDI mass spectrum, PS with a terminal bromine was not detected but the species with a terminal double bond (U series), and −22 m/z (T series) and +18 m/z (W series) peaks relative to U series appeared as major peaks. While the U species was reported as a result of the elimination reaction of HBr, but the origin and the structure of the other species have not been elucidated. We found that the −22 m/z peak of U_n is in fact T_n-2, which is the adduct of THF and the anion of the Ag salt, TFA⁻ (+186 m/z) to U_n-2. The +18 m/z peak was confirmed to be the species with a terminal OH. All these reactions were catalyzed by Ag salt and the T and W series were not found at all when NaTFA was used as a cationization agent.     

Evaluation of MALDI-TOF/MS Technology in Olive Oil Adulteration

Adulteration of extra virgin olive oil (EVOO) by addition of other vegetable oils or lower-grade olive oils is a common problem of the oil market worldwide. Therefore, we developed a fast protocol for detection of EVOO adulteration by mass spectrometry fingerprinting of triacylglycerol (TAG) profiles based on MALDI-TOF/MS. For that purpose, EVOO TAG profiles were compared with those of edible sunflower oil and olive oil composed of refined olive oil and virgin olive oils. Adulteration of EVOO was simulated by addition of sunflower and mixture of refined olive oil and virgin olive oils at 1, 10 and 20% w/w. Results of mass spectrometry TAG profiling were compared with routinely assessed K values for identification of adulteration. MALDI-TOF/MS technology coupled with statistical analysis was proven as useful for detection of adulteration in EVOO at a rate down to 1%. In contrast, standard spectrophotometric methods failed to identify minor adulterations. In addition, the ability of MALDI-TOF/MS in detection of adulteration was tested on EVOO samples from different geographical regions. Results demonstrated that MALDI-TOF/MS technology coupled with statistical analysis is able to distinguish adulterated oils from other EVOO.     

在Freidel-Crafts反应型催化剂作用下的芳烷基醚与芳香族化合物缩聚反应的研究——(Ⅱ)缩聚反应动力学及机理

本文研究了芳烷基醚与芳香族化合物在Friedel-Crafts反应型催化剂作用下缩聚反应动力学.提出了反应速度方程V=k[X]_0[Ar].求得一系列的反应速度常数和反应活化能数据.用核磁共振波谱测定了反应的中间产物——正碳离子,提出了该缩聚反应为正碳离子进攻芳环的亲电取代机理模型.     

Identification of Dermatophyte Species after Implementation of the In-House MALDI-TOF MS Database

Despite that matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has become a powerful tool in the clinical microbiology setting, few studies have till now focused on MALDI-TOF MS-based identification of dermatophytes. In this study, we analyze dermatophytes strains isolated from clinical samples by MALDI-TOF MS to supplement the reference database available in our laboratory. Twenty four dermatophytes (13 reference strains and 11 field isolated strains), identified by both conventional and molecular standard procedures, were analyzed by MALDI-TOF MS, and the spectra obtained were used to supplement the available database, limited to a few species. To verify the robustness of the implemented database, 64 clinical isolates other than those used for the implementation were identified by MALDI-TOF MS. The implementation allowed the identification of the species not included in the original database, reinforced the identification of the species already present and correctly identified those within the Trichophyton mentagrophytes complex previously classified as Trichophyton. tonsurans by MALDI-TOF MS. The dendrogram obtained by analyzing the proteic profiles of the different species of dermatophytes reflected their taxonomy, showing moreover, in some cases, a different clusterization between the spectra already present in the database and those newly added. In this study, MALDI-TOF MS proved to be a useful tool suitable for the identification of dermatophytes for diagnostic purpose.     

Combined MALDI-TOF MS and NMR characterization of copoly(arylen ether sulphone)s

The synthesis and the chemical characterization of some novel random copolyethersulphones of the type P(ESES-co-EES) (Polyethersulphone-ethersulphone:Polyetherethersulphone), is reported. The ESES:EES molar ratio was varied from 80:20 to 20:80 and all the copolymers were terminated with reactive amino groups, and then were fully characterized through (¹H and ¹³C)-NMR and MALDI-TOF MS analysis to confirm their chemical structures and chemical compositions. End chains were revealed by these techniques. Contrary to chlorine-ended copolymers, oligomers terminated with hydroxyl groups were revealed in the amine-ended copolymers, indicating that transetherification reactions occur during the capping reaction with m-aminophenol. Cycles were also revealed by MALDI-TOF MS, that revealed also some unexpected end chains may be formed for the impurities in the feed. The glass transition temperatures of the copolymers have been determined by differential scanning calorimetry (DSC).     

3-氨基喹啉与常用基体在MALDI-TOFMS测定天然提取植物多糖的比较

采用3-氨基喹啉(3-AQ)、二元基体3-AQ/2,5-二羟基苯甲酸(DHB)及常用于糖类物质测定的DHB和二元基体DHB/1-羟基异喹啉(1-HIQ)对一天然提取植物糖样进行了基体辅助激光解吸/电离飞行时间质谱(MALDI-TOF MS)分析。实验结果表明:此植物糖样由线形和环形聚己糖组成,其最大分子量至少达3000 Da;3-AQ与常用基体DHB及DHB/HIQ相比较,能提供更准确、更全面的样品组成及分子结构信息,且具有优越于常用基体解吸电离环状糖分子的能力。     

二维电泳-质谱分析麦拓莱霉素发酵过程中差异蛋白

引言 本课题组从土壤中筛选到一株藤黄灰链霉菌菌株,该菌株能产生一种新型的抗生素--麦拓莱霉素.麦拓莱霉素具有抗HIV蛋白酶活性和抗Coxsackie-virus B6 病毒 [1]活性,有很好的工业化前景.但目前产量还比较低,其生产过程的优化和产量的提高是亟待解决的问题.     

Detection of Ricin Intoxication in Mice Using Serum Peptide Profiling by MALDI-TOF/MS

Ricin toxin has been regarded as one of the most potent poisons in the plant kingdom, and there is no effective therapeutic countermeasure or licensed vaccine against it. Consequently, early detection of ricin intoxication is necessary. In this study, we took mice as test subjects, and used the technique of Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) and ClinProt™ microparticle beads to set up an effective detection model with an accuracy of almost 100%. Eighty-two peaks in the mass range 1000–10,000 m/z were detected by ClinProTools software, and five different peaks with m/z of 4982.49, 1333.25, 1537.86, 4285.05 and 2738.88 had the greatest contribution to the accuracy and sensitivity of this model. They may therefore provide biomarkers for ricin intoxication.     

Polycondensation of N-Chlorobenzoquinonimines

Summary Self-condensations of 4-chloroimino-2, 5-cyclohexadiene-1-one 1 (benzoquinone N-chloroimine), 2-tert-butyl-4-chloroimino-2, 5-cyclohexadiene-1-one 2, and 3-tert-butyl-4-chloroimino-2, 5-cyclohexadiene-1-one 3 in N-methylpyrrolidinone containing inorganic bases have been investigated. Monomer 1 gave polymers having inherent viscosities of 0.27–0.33 dLg^–1. Monomers 2 and 3 only gave oligomers. ¹H NMR spectra suggest that polymerization of 1 mainly occurs at C-2 and C-6 positions. A Michael-type addition mechanism, based on the high -effect nucleophilicity of =NCl, is proposed.     

Hyaluronidase Alters the Lipid Profile of Cumulus Cells as Detected by MALDI-TOF MS and Multivariate Analysis

This research aimed to study the changes in lipid composition in cumulus cells using hyaluronidase according to the intracytoplasmic sperm injection protocol commonly used in human reproduction clinics. The lipid extraction was performed by the Blight‐Dyer protocol and the lipid profiles were obtained by MALDI‐TOF MS in positive and negative modes. The mass spectra data were processed with MassLynx and the statistical analysis was performed using MetaboAnalyst 2.0. Fifteen ions were selected for each mode as potential markers for differences between the groups. These ions were identified in the human metabolome database as phosphatidylserine with and without treatment, phosphatidylethanolamine in the after treatment group and phosphatidylinositol in the before treatment group, which are lipids that may be involved in cell apoptosis and signaling. We concluded that MALDI‐TOF MS coupled with multivariate analysis can be utilized as a strategy to obtain and study the lipid profiles of cumulus cells and as a tool to study the metabolic state of cumulus cells.     

Poly(dibenzodiazocine)s: analysis of low molecular weight fractions by MALDI-TOF MS

Poly(dibenzodiazocine)s, members of a new class of polyimines with high thermal stability and solubility in organic solvents, were synthesized from 2-amino-4′-fluorobenzophenone and three bisphenols. The high molecular weight polymers were shown by MALDI-TOF mass spectra to be accompanied by low molecular weight linear oligomers with the expected end group combinations and low molecular weight cyclic oligomers. The yields of the smaller cyclics were raised using a pseudo-dilution polymerization method.     

粉煤灰加气砼的水化产物及其结构的研究

用扫描电镜研究了粉煤灰加气砼中各种水化产物的微观形态 ,对高、低温度蒸养的粉煤灰加气混凝土中水化物的种类和微观结构进行了观察分析。结果表明 :低温养护水化产物较少 ,结构疏松 ;高温蒸养水化产物较多 ,结构密实     

超高效液相色谱-串联质谱法测定无糖食品中木糖的含量

以自制的13C-木糖为内标,建立了无糖食品中木糖的高效液相色谱-串联四级杆质谱联用测定法。以Phenomenex Lichrosorb 5色谱柱(250mm×4.6mm,5μm)为分离柱,乙腈-水(V/V=80∶20)为流动相,以水提取样品,在电喷雾正离子选择反应检测模式下进行定性定量分析。该方法的检出限为10ng/mL,线性范围为10～1000ng/mL,加标回收率为96.09%～99.90%,相对平均偏差(n=5)为1.2%～2.5%。     

X-Ray Studies of Lime-Bentonite Reaction Products

Calcium aluminate and calcium silicate hydrates were formed in mixtures of bentonite with water and various types of lime which had been sealed and cured for up to three years at 23°± 2°C and 100% relative humidity. Methods of analysis were X-ray diffraction and electron microscopy. Hydrothermal treatment of the cured mixtures at 170°C for 12 hr produced well-crystallized tobermorite with apparent lattice substitution of aluminum. The same result was obtained by hydrothermal treatment of identical uncured mixtures.     

液相色谱-串联质谱法测定乳制品中的氯霉素

建立了超高效液相色谱-串联质谱/质谱法测定奶粉、凝固型酸奶及液态奶中氯霉素的方法。试样用10%亚铁氰化钾及20%乙酸锌作为沉淀剂,以乙酸乙酯提取,采用电喷雾离子源,负离子扫描,多反应监测(MRM)模式进行检测,外标法定量。结果表明,氯霉素在0.5~100μg/L浓度范围内线性关系良好,空白样品加标回收率均大于80%,相对标准偏差小于6%。氯霉素方法检出限(LOD)均为0.1μg/kg。该方法准确、灵敏、操作相对简便,有效降低基质干扰,适用于奶粉、牛奶中氯霉素的测定。     

Characteristic Oxidation Products of Choline Plasmalogens are Detectable in Cattle and Roe Deer Spermatozoa by MALDI-TOF Mass Spectrometry

Plasmalogens (1-O-alk-1′-enyl-2-acyl-sn-glycero-3-phosphocholines and -phosphoethanolamines) are important constituents of spermatozoa membranes and possess significant antioxidative properties. This particularly holds as plasmalogens from spermatozoa also possess a very high content of highly unsaturated fatty acyl residues (especially 22:6). The organic spermatozoa extracts of two different ruminants (cattle and roe deer) were analyzed for their contents of characteristic choline plasmalogen oxidation products by matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry. It will be shown that 1-hydroxy-2-docosahexaenoyl-sn-glycero-3-phosphocholine (LPC 22:6) and formyl-LPC 22:6 are reliable measures of lipid oxidation of spermatozoa and allow, accordingly, conclusions about the storage conditions. All data on spermatozoa were also confirmed by the investigation of the oxidation behavior of selected reference compounds. It will be shown that, equally if plasmalogens or diacyl PC species are used, oxidation takes place primarily at the double bond next to the glycerol backbone. These data were additionally confirmed by recording the corresponding post source decay (PSD) fragment ion spectra.     

气相色谱/质谱联用分析橡胶制品喷霜析出物

用气相色谱/质谱联用(GC/MS)对汽车门窗密封条、橡胶手套、白胶板、轮胎等喷霜析出物进行分析。从GC/MS总离子流色谱分析得出,橡胶制品喷霜析出物主要为防焦剂、促进剂、防老剂、防护蜡和硬脂酸等。GC/MS分离效果好,测试效率高,可以较准确地分析橡胶制品的喷霜析出物。     

Investigation of ethylene oxide oligomerization during functionalization of poly(butadienyl)lithium using MALDI-TOF MS and H NMR analyses

Oligomerization of ethylene oxide during the functionalization of poly(butadienyl)lithium in benzene and cyclohexane at 25 °C has been investigated by MALDI-TOF MS and ¹H NMR. Chemically significant amounts of oligomer were found using 4 equiv. of ethylene oxide ([EO]/[PLi]) after 12 h in both benzene and cyclohexane. No oligomer was observed when the reaction time was minimized.