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报家长在体辅助激光解吸电离质谱法(MALDI-MS)测定DNA分子的一种有效基体3-羟基-4-甲氧基肉桂酸。实验发现该基体对DNA分子解吸和电离效率高,对DNAd(T)10分子离子峰的分辨率为5551.4倍,噪比为11.8。3-羟基-4-甲氧基肉桂酸是MALDI-MS法测定DNA分子的一个可供选择使用有效基体。 相似文献
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3种羧酸类基质的基质辅助激光解吸/电离质谱行为 总被引:1,自引:0,他引:1
1引言基质辅助激光解吸/电离质谱(MALDI-MS)这种新的“软电离”质谱技术,能够在短短10年间,得到广泛应用与迅速发展,很大程度上要归功于基质的辅助效应。基质在样品的解吸/电离过程中,起着关键作用。对基质本身MALDI-MS的研究,不仅可以、刻认识MALDI-MS中离子生成、碎裂的机制,在低分子量物质分析时更是必不可少。我们选择常用的3种羧酸类基质:2,5-二羟基苯甲酸(2,5-DHB)、芥子酸(SA)、α-CN-4羟基肉桂酸(ACHC),进行了其自身MALDI-MS的研究。2实验部分2.1… 相似文献
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报道以2-氨基-5-硝基吡啶为基体用基体辅助激光解吸/电离质谱法(MALDI-MS)对DNA样品进行测定并研究它们的激光质谱特征,结果表明,2-氨基-5-硝基吡啶是DNA的一高铲基体。用柠檬酸铵和NH^+4阳离子交换树脂除去试剂和样品中的碱金属离子,能显著地提高解吸/电离DNA分子的效率。 相似文献
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基体辅助激光解吸—电离飞行时间质谱法分析衍生化的寡链糖 总被引:1,自引:0,他引:1
以2,5-二羟基苯甲酸(DHB)+间硝基苄醇(NBA)混合基体辅助激光解吸电离飞行时间质谱法(MALDI)分析甲壳素降解并衍生化的寡链糖,获得了满意的结果。对比其它基体,如:芥子酸(SA)、α-氰基-4-羟基肉桂酸等(α_CHCA),2,5_DHB+NBA混合基体解吸电离效果最好:信号强、信噪比高。甲壳素降解产物的质谱分析至今未见报道。 相似文献
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基体辅助激光解吸/电离质谱(MALDIMS)法自80年代末由Karas,Hilenkamp报道以来,已获得极大的发展.近几年来,其应用范围迅速扩大,各种生物大分子如蛋白质,核酸(DNA),多糖等都已能用MALDIMS法进行分子量测定.1993年,... 相似文献
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研究了基体溶液的pH值对基体辅助激光解吸电离(MALDI)的影响,测定了从强酸至强碱不同pH值的α-氰基,4-羟基肉桂酸水溶液的紫外吸收谱,并分别用作基体测定细胞色素C的相对分子质量。结果显示除按常规配制的基体溶液(pH=2.5)在激光波长355nm处有强紫外吸收外,其他pH=1.0、pH=8.0、pH=10.0的溶液皆没有吸收,而相对分子质量测量结果是pH=1.0和pH=2.5两种溶液可得到质量 相似文献
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研究了基体溶液的pH值对基体辅助激光解吸电离(MALDI)的影响,分别测定了从强酸至强碱不同pH值的α-氰基,4-羟基肉桂酸水溶液的紫外吸收谱,并分别用作基体测定细胞色素C的相对分子质量。结果显示除按常规配制的基体溶液(pH=25)在激光波长355nm处有强紫外吸收外,其他pH=10、pH=80、pH=100的溶液皆没有吸收,而相对分子质量测定结果是pH=10和pH=25两种溶液可得到质量良好的谱图。而pH=80和100的两种溶液则得不到谱图,作者还以溶液化学规律,及基体辅助激光解吸电离的机理,对结果进行了讨论。 相似文献
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(6,7-二甲氧基-4-亚甲基香豆素基)单氮杂-18-冠-6的合成及其离子识别功能(I)--合成及光谱性质 总被引:1,自引:0,他引:1
合成、鉴定了具有离子识别功能的题示光敏离子载体(6,7-二甲氧基-4-亚甲基香豆素基)单氮杂-18-冠-6 (DMC-MAC(O5)),研究了它在水中的吸收和荧光光谱,基于不同pH值水溶液中荧光光谱的变化,计算得该试剂激发态分子的酸性常数pKa= 6.00。基于在不同溶剂中荧光光谱的变化,由Solvachrom ic法,利用Lippert方程并借助Alchem y 2000量化计算软件,采用分子力学模型(MM3),估算得该分子的基态和激发态偶极矩,分别为2.75D和7.84D。DMC-MAC(O5)保留了6,7-二甲氧基香豆素(DMC)优良的发光性能,为其离子识别功能的研究奠定了良好的基础。 相似文献
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M. E. Carlotti S. Sapino E. Ugazio E. Peira D. Vione C. Minero 《Journal of Dispersion Science and Technology》2013,34(5):629-640
Ferulic acid (4‐hydroxy‐3‐methoxycinnamic acid), a phenyl‐propenoid derivative of cinnamic acid, can undergo photolysis upon UV irradiation. The photodegradation kinetics of ferulic acid were thus investigated in different systems. The micellar solutions did not protect the acid from photodegradation. On the contrary, they catalyzed its degradation at a variable extent depending on the surfactant structure. The photodegradation of ferulic acid in microemulsions was slower than in micelles and near to that in water. TiO2, habitually employed as a physical sunscreen, showed photocatalytic action toward ferulic acid degradation especially at higher initial concentration of ferulic acid. The action of ferulic acid on the peroxidation of linoleic acid in micelles and microemulsions also was evaluated. When the ferulic acid is absent the peroxidation is continuous while when it is present an induction time of 40 minutes or higher was observed. Accordingly, it is likely that linoleic acid acts as photosensitizer for ferulic acid, and that in turn ferulic acid acts as an antioxidant for linoleic acid, reducing the rate of peroxidation. 相似文献
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M. George J. M. Y. Wellemans R. L. Cerny M. L. Gross K. Li E. L. Cavalieri 《Journal of the American Society for Mass Spectrometry》1994,5(11):1021-1025
Two matrices, 4-phenyl-α-eyanocinnamic acid (PCC) and 4-benzyloxy-α-eyanocinnamic acid (BCC), were identified for the determination of polycyclic aromatic hydrocarbon (PAH) adducts of DNA bases by matrix-assisted laser desorption ionization. These matrices were designed based on the concept that the matrix and the analyte should have structural similarities. PCC is a good matrix for the desorption of not only PAH-modified DNA bases, but also PAHs themselves and their metabolites. Detections can be made at the femtomolar level. 相似文献
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Wei Xu Jia‐Mei Wu Zheng Zhu Yi Sha Jin Fang Yu‐Shan Li 《Helvetica chimica acta》2010,93(10):2007-2014
Three new pentacyclic triterpenoid saponins, viscidulosides A and B ( 1 and 2 , resp.), and silenoviscoside D ( 3 ), were isolated from the roots of Silene viscidula, together with two known saponins, sinocrassulosides VIII and IX ( 4 and 5 , resp.). Their structures were elucidated by spectroscopic data and chemical methods. Compounds 1 / 2 and 4 / 5 were two inseparable mixtures, which are glycosides of quillaic acid whose fucose residue is acylated by (E)‐ or (Z)‐4‐methoxycinnamic acid. 相似文献
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Martin Körsgen Andreas Pelster Klaus Dreisewerd Heinrich F. Arlinghaus 《Journal of the American Society for Mass Spectrometry》2016,27(2):277-284
The analytical sensitivity in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is largely affected by the specific analyte-matrix interaction, in particular by the possible incorporation of the analytes into crystalline MALDI matrices. Here we used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to visualize the incorporation of three peptides with different hydrophobicities, bradykinin, Substance P, and vasopressin, into two classic MALDI matrices, 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (HCCA). For depth profiling, an Ar cluster ion beam was used to gradually sputter through the matrix crystals without causing significant degradation of matrix or biomolecules. A pulsed Bi3 ion cluster beam was used to image the lateral analyte distribution in the center of the sputter crater. Using this dual beam technique, the 3D distribution of the analytes and spatial segregation effects within the matrix crystals were imaged with sub-μm resolution. The technique could in the future enable matrix-enhanced (ME)-ToF-SIMS imaging of peptides in tissue slices at ultra-high resolution. 相似文献
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Five new aromatics bearing a 4‐O‐methylglucose unit, namely 3‐methoxy‐1,4‐hydroquinone 1‐(4′‐O‐methyl‐β‐glucopyranoside) (=4‐hydroxy‐3‐methoxyphenyl 4‐O‐methyl‐β‐glucopyranoside; 1 ), 3‐methoxy‐1,4‐hydroquinone 4‐(4′‐O‐methyl‐β‐glucopyranoside) (=4‐hydroxy‐2‐methoxyphenyl 4‐O‐methyl‐β‐glucopyranoside; 2 ), vanillic acid 4‐(4′‐O‐methyl‐β‐glucopyranoside) (=3‐methoxy‐4‐[(O‐methyl‐β‐glucopyranosyl)oxy]benzoic acid; 3 ), 5‐methoxycinnamic acid 3‐O‐(4′‐O‐methyl‐β‐glucopyranoside) (=(2E)‐3‐{3‐methoxy‐5‐[(4‐O‐methyl‐β‐glucopyranosyl)oxy]phenyl}prop‐2‐enoic acid; 4 ), and naphthalene‐1,8‐diol 1,8‐bis(4′‐O‐methyl‐β‐glucopyranoside) (=naphthalene‐1,8‐diyl bis(4‐O‐methyl‐β‐glucopyranoside; 5 ), were isolated from the cultivated Cordyceps cicadae mycelia, together with thirteen known compounds. Their structures were determined by spectroscopic methods. The absolute configurations of the sugar units were not determined. 相似文献
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Yuko Fukuyama Shunsuke Izumi Koichi Tanaka 《Journal of the American Society for Mass Spectrometry》2018,29(11):2227-2236
In in-source decay (ISD) in matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS), 1,5-diaminonaphthalene (1,5-DAN) is a most frequently used matrix probably due to the highly sensitive detection of fragment ions. 1,5-DAN is a reducing matrix generating c- and z-series ions by N–Cα bond cleavage. However, it is difficult for reducing matrices to distinguish leucine and isoleucine, and generate c(n-1)-series ions owing to proline (Pro) at residues n. Oxidizing matrices providing a- and x-series ions accompanied by d-series ions by Cα–C bond cleavage solve the problem, but their sensitivity of the ISD fragment ions has been lower than reducing matrices such as 1,5-DAN. Recently, 3-hydroxy-4-nitrobenzoic acid (3H4NBA) had been reported as an oxidizing matrix generating a-series ions with higher intensity compared with conventional oxidizing matrices such as 5-nitrosalicylic acid, but a little lower intensity compared with 1,5-DAN (Anal Chem 88, 8058–8063, 2016). In this study, 3H4NBA isomers (2H3NBA, 2H4NBA, 2H5NBA, 2H6NBA, 3H2NBA, 3H5NBA, 4H2NBA, 4H3NBA, 5H2NBA, and 3H4NBA) were evaluated. All the isomers generated a-series ions accompanied by d-series ions, wherein 3H2NBA, 3H5NBA, 4H2NBA, 4H3NBA, and 5H2NBA were first confirmed as oxidizing matrices for ISD. Among the isomers, 3H2NBA and 4H3NBA generated a-series ions with higher peak intensity compared with 3H4NBA for several peptides. Especially, 3H2NBA generated a-series ions with almost the same or higher intensity, and clearly higher peak resolution compared with c-series ions using 1,5-DAN in several cases. 3H2NBA was expected to contribute to ISD analyses in MALDI-MS as one of the most effective oxidizing matrices. 相似文献
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石墨炉原子吸收光谱中氯化铕和硝酸铕背景吸收来源与特点的研究 总被引:1,自引:0,他引:1
研究了石墨炉原子吸收中氯化铕和硝酸铕背景吸收的来源、特点和消除方法。氯化铕背景吸收来源于其分解产物EuCl_2蒸气和Cl_2,而硝酸铕背景吸收来源于其分解产物NO和Eu_2O_3蒸气。测定铕中微量元素时,可通过选择灰化温度、记录原子吸收峰时间或加硝酸作基体改进剂等方法米减少、甚至完全消除背景吸收的干扰。 相似文献