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1.
张颖 《分析测试学报》2004,23(Z1):282-283
采用齐格勒-钠塔催化剂使丙烯催化聚合得到聚丙烯。聚丙烯树脂本身具有优良的性能,如机械强度好,易加工成型,质量轻,成本低等,但也存在一些缺陷,如由于聚丙烯结构中存在叔碳原子,在造粒加工、贮存和使用过程中,易受热、光、氧等的作用而降解,导致材料的性能降低。为了抑制和延缓聚丙烯的氧化降解,需要在造粒阶段加入抗氧剂。本文以一种聚丙烯树脂样品为研究对象,采用溶剂抽提法提取有机添加剂,并用柱层析法对添加剂进行了分离;利用EI-MS分析了添加剂的组成,其中通过谱图解析,鉴定出添加剂中含有硫酯类抗氧剂-硫代二丙酸二(十四)酯(DMTP),并用此类常用化合物进行了验证,分析结果对树脂牌号的开发具有指导意义。  相似文献   

2.
Wenjing Wang  Hui Liu  Zhili Li 《中国化学》2011,29(11):2229-2235
Sialylation of glycoproteins is vital for the function or physicochemical properties of a protein. It becomes more and more important to develop approaches that can be used to efficiently isolate and identify sialylated glycopeptides or glycoproteins for monitoring changes in glycoproteome. In the present study, we analyze intact structures of the enriched sialylated glycopeptides of bovine fetuin by matrix‐assisted laser desorption/ionization‐tandem mass spectrometry (MALDI‐MS/MS), without any chemical derivation. The experimental data show that the optimal loading buffer for TiO2 as matrix is 80% acetonitrile/2% TFA (trifluoroacetic acid)/100 mg/mL DHB (2,5‐dihydroxybenzoic acid) which is also compatible with MALDI‐mass spectrometric analysis. This study indicates that the improved enrichment approach combined with MALDI‐MS/MS may be a powerful tool to analyze intact structures and components of the sialylated glycopeptides from complex peptide mixture.  相似文献   

3.
Nie Z  Liu Q  Xie J 《Talanta》2011,85(2):1154-1159
The N-terminal valine adduct (HETE-Val) in globin is believed to behave as a long-lived biomarker after exposure to sulfur mustard (HD). Development of a highly sensitive method for monitoring HETE-Val, particularly at low HD exposure levels or for retrospective detection, would be a significant achievement. In this study, by improving the sample preparation method, a sensitive NCI-GC/MS method was established for the analysis of HETE-Val in globin after HD exposure. To optimize and investigate the sample preparation method, all the relevant HETE-Val chemicals were synthesized, purified, and characterized. By carrying out optimized solid phase extraction (SPE) cleanup followed by modified Edman degradation results in a low detection level and clean baseline. The minimum detectable exposure level of human blood (in vitro) to HD is 20 nmol/L (S/N > 3). The interday and intraday precisions of the proposed method were found to be acceptable with less than a 15% relative standard deviation (RSD). A nearly linear dose-effect relationship was observed between HETE-Val and a HD exposure concentration range of 0.1-120 μmol/L. The percentage of HD that reacted with N-terminal valine in globin obtained from human blood (in vitro) was quantified using the proposed method.  相似文献   

4.
刘百战 《分析化学》2000,28(12):1489-1492
采用固相微萃取和同时蒸馏萃取技术分离芥末膏制品的挥发性成分,用GC/MS分析鉴定,对总离子流色谱的峰面积进行归一化定量。共鉴定了22种化学成分,占总峰面积的99%以上,其中含硫化合物8种,含氮化物3种,含氧化合物11种。最主要的成分是异硫氰酸烯丙酯,其次是丙二醇,其他主要成分还有对羟基二叔丁基甲苯、油酸、9-十六烯酸、棕榈酸、5-甲基甲氢噻吩-2酮、二烯丙基二硫化物,异硫氰酸苯乙酯等。比较了各种萃取技术对分析结果的影响,同时蒸馏萃取法不能分离出水溶性成分如丙二醇等,在固相微萃取方法中,聚二甲基硅氧烷纤维头对极性较强的成分的取样效果不理想,聚乙二醇-二乙烯苯纤维头顶空取样的萃取效果最好。  相似文献   

5.
采用电喷雾-离子阱-飞行时间串联质谱(ESI-IT-TOF)技术, 在正/负离子检测模式下对芒柄花素及其同分异构体7-甲氧基异黄酮的质谱裂解规律进行了系统研究. 实验结果表明, 该化合物在正、负离子模式下均得到了5级高分辨质谱. 结果显示, 二者在负离子模式下的碎片相同, 而在正离子模式下的碎片裂解不同. 根据正负离子模式的5级高分辨质谱推导了两者的可能裂解规律, 丰富了异黄酮的ESI-MSn数据, 为其它异黄酮类化合物的分析鉴定提供了有效的质谱方法.  相似文献   

6.
Cyclotides, a class of macrocyclic plant peptides, characterized by a cyclic backbone and three inter-locking disulfide bonds, may be divided into two major structural subfamilies, Möbius and Bracelet, based on the presence or absence of a specific proline residue. The present study describes the suite of cyclotides obtained from Clitoria ternatea, characterized by LC−MS and MS/MS techniques. Notable variations in product ion distributions were observed in cyclotides belonging to different structural subfamilies based on the number and positions of proline residues. For instance, Cter M which is an abundant Möbius cyclotide in this plant containing three proline residues, displayed distinct b- and y- ion characteristics in the MS/MS spectra compared to Cliotide T1, another commonly identified cyclotide but belonging to the Bracelet subfamily having two proline residues. The distinct fragmentation pattern of prototypical cyclotides of each structural subfamily, determined by Xxx-Pro bond fragmentation, was used to rapidly identify and sequence a novel cyclotide ctr pep 30 from this plant.  相似文献   

7.
《Analytical letters》2012,45(15):2311-2317
The present work describes the methodology and validation of gas chromatography with flame ionization (FID) and mass spectrometric (MS) detection after derivatization with N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) for determination of atenolol with an internal standard (metoprolol) in pharmaceutical preparations. The linearity was established over the concentration range of 0.5–20 μg/mL for GC/FID and 12.5–500 ng/mL for GC/MS method. The intra- and inter-day relative standard deviation was less than 4.72 and 5.80%, respectively. Limit of quantification was determined as 500 ng/mL and 12.5 ng/mL for GC/FID and GC/MS, respectively. No interference was found from tablet excipients at the selected assay conditions. Developed GC/FID and GC/MS methods in this study are accurate, sensitive, and precise and can be easily applied to Tensinor tablet as pharmaceutical preparation.  相似文献   

8.
This work describes the electrochemical properties of glassy carbon electrodes (GCE) modified with chromium(III) hexacyanoferrate(II) (Crhf) nanoparticles attached multiwalled carbon nanotube (MWNTs). The morphological characterization of Crhf/MWNTs nanocomposites was examined by scanning electron microscopy (SEM), UV‐vis spectroscopy, and Fourier transform infrared spectrometry (FT‐IR). The electrocatalytic activity of these nanocomposites was investigated and showed a good electrocatalytic effect for oxidation of L ‐cysteine (L ‐Cys) in 0.1 M phosphate buffer solution (pH 3.0). Under optimum conditions linear calibration graphs were obtained over the L ‐Cys concentration range 5.0×10?7 to 6.0×10?5 M with a correlation coefficient of 0.9998 and a detection limit (signal‐to‐noise ratio was 3) of 1.0×10?8 M. The proposed method is simple and it also showed excellent sensitivity and stability. The excellent electrocatalytic ability of the modified electrode towards L ‐Cys manifests that the Crhf/MWNTs can provide a new platform for biosensors and other biology.  相似文献   

9.
A series of phosphonothiolates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) ethyl methylphosphonothioate (VX), have been subjected to chemical neutralization reaction with metallic sodium. The phosphonothiolates decompose to their respective phosphonic and phosphonothioic acids and this results in the detoxification of VX. GC/MS technique in both EI and CI mode has been applied for reaction monitoring and final identification of the neutralization products formed in this reaction.  相似文献   

10.
以离子色谱-质谱联用同时测定了不同品牌牛奶中的高氯酸盐、溴酸盐和碘离子。以高容量、强亲水性IonPac AS20(2 mm)为分析柱,EGC在线产生KOH为淋洗液,串联质谱检测。ESIMS/MS以多元反应监测(MRM)模式分别监控高氯酸盐的m/z100.8/84.9、98.8/82.9离子对,溴酸盐的m/z126.8/110.9、126.8/95.0离子对和碘离子的m/z126.8/127.0离子对,并分别对高氯酸盐、溴酸盐和碘离子以m/z98.8/82.9、126.8/110.9和126.8/127.0离子对的峰面积进行定量。该方法对高氯酸盐、溴酸盐和碘离子的检出限(S/N=3)分别为0.02、0.1和0.5μg/L,线性相关系数分别是0.999(0.05~50μg/L)、0.999(0.5~100μg/L)、0.998(1~1 000μg/L)。高氯酸盐和碘离子的样品加标回收率分别在102%~108%之间和86%~114%之间。  相似文献   

11.
Functionalized iron oxide nanoparticles (IONPs) were used as concentrating probes to extract substance P (SP) from aqueous solution before matrix‐assisted laser desorption/ionization mass spectrometric (MALDI/MS) analysis. Adsorption of SP onto the nanoparticles was mainly due to electrostatic interaction. After simple washing, the SP‐adsorbed nanoparticles were directly analyzed by MALDI/MS. With this concentration strategy, the limit of detection (LOD) of SP in 500 μL buffer solution (pH 8) was 0.1 nM. In addition, the nanoparticles could isolate SP from a solution with high contents of salts and surfactants, thus alleviating suppression effect during MALDI/MS analysis. This new method was successfully applied to the determination of SP in rat spinal cord samples. The LOD and recovery of SP in a rat spinal cord sample were 3.1 nM and 85.7%, respectively.  相似文献   

12.
13.
采用原位模板法,以六氯环三磷腈(HCCP)和二羟基二苯砜(BPS)为原料合成了一种环状交联型不溶不熔的磷腈大分子——聚环三磷腈-二羟基二苯砜(PZS)微纳米管,研究了PZS对环氧树脂(EP)的阻燃作用及阻燃机理.利用红外光谱(FTIR)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)对PZS微纳米管进行了表征;采用热重分析(TG)考察了EP/PZS阻燃材料的热稳定性,并通过极限氧指数(LOI)和微型量热分析(MCC)测试了EP/PZS的阻燃性能.热降解实验结果表明,PZS微纳米管的加入使环氧树脂热降解温度降低,但残炭率显著提高.PZS微纳米管可以显著提高环氧树脂的阻燃性能,当阻燃剂添加量为5%时,环氧树脂的残炭率提高了46%,热释放速率峰值降低了约40%;LOI值从纯环氧树脂的26.0%提高到了30.6%.PZS微纳米管的加入还增强了环氧树脂的力学强度.阻燃性能的显著提高和力学性能的改善归因于PZS微纳米管在环氧树脂基体中的良好分散,以及燃烧炭化过程中生成的石墨化程度较高的类石墨烯结构的残炭,具有较高的抗氧化能力.研究结果表明,PZS微纳米管是一种优良、高效的具有潜在应用价值的阻燃剂.  相似文献   

14.
质谱法分析季铵盐型阳离子表面活性剂   总被引:1,自引:0,他引:1  
以电子轰击质谱法(EI/MS)与电喷雾质谱法(ESI/MS)相结合,分析季铵盐型表面活性剂。由于阳离子表面活性剂在水溶液中离解成正离子,可用电喷雾质谱的正离子模式(ESI /MS)对其结构及组成进行鉴定,同时可判别季铵盐所含的Cl-、Br-、NO3-等阴离子。  相似文献   

15.
《Analytical letters》2012,45(14):1749-1757
Abstract

The GC/MS spectra of the methyl adduct of PBN as the aminoxyl and as the corresponding hydroxylamine are reported. Similar results are obtained with higher alkyl analogues. With excess alkyl Grignard the O-alkyl hydroxylamine ether (PBN double adduct) is obtained if the solution is exposed to O2 in the presence of the alkyl spin adduct of PBN. A mechanism involving radical trapping by the alkyl spin adduct is proposed.  相似文献   

16.
Abstract

The ICP/MS method with lutetium, bismuth and indium as internal standards was used for the determination of thallium and other elements, i.e. Ti, V, Cr, Ni, Cu, Zn, Rb, Mo, Cd, As and Pb, in soils and rapeseeds. Samples were collected in two thallium highly pedogeochemicaily contaminated areas situated in South Bohemia and in Czech-Moravian Highlands, in two river alluvia, in two control sites with low levels of TI and in one spot with anthropogenic contamination. Levels higher than 2.5 mg kg?1 have been found in rapeseeds in the highly polluted areas (c. 2.8 mg kg?1 in soils). High correlation coefficients, r > 0.81, between content of TI in top- and sub-soils and rapeseeds were obtained. Thallium concentrations exceed twice of Pb content and by one order of magnitude of Cd amounts. This finding are very important because of the high toxicity of TI and the absence of threshold limits for TI in soils, agricultural products and foodstuffs in the Czech Republic.  相似文献   

17.
兰索拉唑(lansoprazole)为新型的抑制胃酸分泌的药物,临床上用于十二指肠溃疡、胃溃疡、返流性食管炎等的治疗,疗效显著,对幽门螺杆菌有抑制作用[1-2]。我们以2-[[[3-甲基-4-(2,2,2-三氟乙氧基)-2-吡啶基]甲基]巯基]-1H-苯并咪唑为原料,成功地制得了兰索拉唑(2-[[3-甲基-4-(2,2  相似文献   

18.
以糖蛋白核糖核酸酶B(RNase B)为研究对象,采用基质辅助激光解吸电离-串联飞行时间质谱(MALDI-TOF/TOF-MS)、傅里叶变换离子回旋共振质谱(FT-ICR-MS)的碰撞活化解离(CAD)和电子转移解离(ECD)多种质谱技术对RNase B的糖肽的完整信息进行解析.通过多种质谱相互验证,确定了RNase B的糖肽组分的氨基酸序列为SRNLTK、糖链结构为(HexNAc)2(Hex)5-(HexNAc)2(Hex)9及糖基化位点为第34位氨基酸残基.本方法为糖蛋白结构的全面解析提供了一种快速、有效、全面的研究思路.  相似文献   

19.
3,5-Dimethoxyhomophthalic acid was synthesized in four steps from 3,5-dimethoxycinnamic acid via a series of reactions including cyclization of 3-(3',5'-dimethoxyphenyl)propionic acid to 5,7-dimethoxy-1-indanone and oxidative decomposition of methyl-2-hydroxy-2-[5,7-dimethyoxy-1-oxo-1H-inden-2(3H)-ylidene]acetate to 3,5-dimethoxyhomophthalic acid.The synthesized compounds were characterized by elemental analysis,IR,1H NMR,and MS.The biological evaluation experiments of 3,5-dimthoxyhomophthalic acid and the related synthesized compounds were also carried out.Naturally occurring biologically active isocoumarins were prepared in a single step by the condensation of the homophthalic acid with appropriate acid chlorides.  相似文献   

20.
In this research, we present a detailed comparative analysis of the bioactive substances of soybean varieties k-11538 (Russia), k-11559 (Russia), k-569 (China), k-5367 (China), k-5373 (China), k-5586 (Sweden), and Primorskaya-86 (Russia) using an LSM 800 confocal laser microscope and an amaZon ion trap SL mass spectrometer. Laser microscopy made it possible to clarify in detail the spatial arrangement of the polyphenolic content of soybeans. Our results revealed that the phenolics of soybean are spatially located mainly in the seed coat and the outer layer of the cotyledon. High-performance liquid chromatography (HPLC) was used in combination with an amaZon SL BRUKER DALTONIKS ion trap (tandem mass spectrometry) to identify target analytes in soybean extracts. The results of initial studies revealed the presence of 63 compounds, and 45 of the target analytes were identified as polyphenolic compounds.  相似文献   

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