广西刘寄奴的紫外-可见光谱分析

以水、无水乙醇、石油醚及乙酸乙酯为溶剂分别进行回流提取、超声提取、浸渍提取,对提取液进行紫外—可见光谱法分析。四种溶剂提取液的紫外可见光谱均有特征,水提取液的紫外可见光谱特征吸收峰单一,无水乙醇、乙酸乙酯和石油醚各提取液的特征吸收峰较多;水提取液、无水乙醇各提取液吸收极强,乙酸乙酯、石油醚的提取液吸收较弱。本研究可为广西刘寄奴鉴别和成分分析提供辅助依据。     

红色色酚类色淀颜料的结构与性能

本文对色酚色淀颜料的结构与可见光谱及热稳定性的关系进行了研究。颜料重氦组分带有较多的供电子基或加长偶氦颜料分子的共轭体系，可使其可见吸收产生深色（向红）效应。以色酚Ａｓ系为偶合组分的偶氮颜料，色酚结构苯环上取代基的变化对颜料光谱性能影响较小。重氮组分取代基位置对颜料的热稳定性有较大的影响，分子对称性及偶极矩影响因素中，后者是影响热稳定性的主要因素     

气相色谱-红外光谱联用法快速鉴定毒品种类及其纯度

建立了气相色谱-红外光谱(GC-FTIR)联用技术快速鉴别毒品种类和分析毒品纯度的方法,具有操作简单、分析快和准确性高等优点,适合于鉴别未知毒品。利用红外光谱特征吸收峰和色谱相对保留时间鉴别毒品种类,毒品浓度(y)与其色谱峰相对面积(x)在0.05~1.00 mg/L范围内呈现良好的线性关系,据此确定毒品纯度。本方法用于实际案例分析取得了满意的结果。     

高斯多峰拟合用于混合表面活性剂十二烷基硫酸钠和吐温80临界胶束浓度的测量

报道了可见吸收光谱线型的高斯多峰拟合用于混合表面活性剂十二烷基硫酸钠(SDS)和吐温80临界胶束浓度的测定.具体的做法是以碱性品红(Fuchsin)为探针,测量固定浓度的吐温80对一系列浓度的SDS-碱性品红水溶液体系的可见吸收光谱.其光谱特征是碱性品红二聚体吸收峰和单体吸收峰叠合在一起.用高斯多峰拟合实现了体系可见光...     

磺化金属酞菁的溶剂效应

文章测试了5种磺化金属酞菁在7种不同极性溶剂中的吸收光谱,用N icol理论研究了金属酞菁染料的溶剂效应。实验和理论结果表明,此类化合物最大吸收峰的波数与函数f(n,ε)存在良好的线性关系,线性相关系数都在0.93以上;而Bayliss函数项(n2-1)/(2n2+1)决定了最大吸收波长(λm ax)的位移变化,λm ax总体上随着溶剂折射率的增大而蓝移,随着溶剂极性的增强而红移。基于此结果,提出了通过选择合适的溶剂调节酞菁染料吸收峰的有效方法,从而使酞菁染料更好地应用于激光防护。     

紫外可见光谱归一校正法检测2,4-二硝基苯酚

采用紫外可见光谱作为检测2,4-二硝基苯酚的方法,pH6或pH3时,2,4-二硝基苯酚的特征吸收峰分别为370 nm及260 nm处;在pH 3~6之间,两特征峰共存。文章提出一种简单的归一拟合方法,首先推导出260 nm处的吸收值与浓度的线性关系,再将pH不同的2,4-二硝基苯酚在370 nm处的吸收值校正到260 nm处。开发了一种简单快捷无需调节pH测定2,4-二硝基苯酚浓度的方法。     

孔雀绿和孔雀绿母体的激光诱导效应：He—Ne激光与循环伏安法

He-Ne激光能促进孔雀绿的阳极氧化速度,增加峰电流的增长速度,但对孔雀绿母体峰电流的增长速度反而减小。溶剂参数π~*与孔雀绿的氧化电位Eox_2及吸收光谱的λ_(max)间有线性关系。在DMSO溶剂中,发现氧化后的孔雀绿,在可见光谱有“烧洞”现象。并观测了“激光诱导后期效应”。     

凹叶景天茎的紫外-可见光谱鉴别

对凹叶景天茎进行紫外-可见光谱定性鉴别的研究,探明其定性鉴别方法。分别以水、95%乙醇、石油醚及乙酸乙酯为溶剂,采用不同的提取方法制备凹叶景天茎的供试液,分别进行紫外-可见光谱测定。凹叶景天茎有一定的光谱特征,同种溶剂不同提取方法吸收峰峰位置波动范围不大。本法操作简便,结果可靠,可为其今后制定鉴别方法提供一定的依据。     

不同环境中孔雀石绿与DNA相互作用的研究

文章对小分子染料孔雀石绿与DNA的相互作用进行了研究,通过紫外可见光谱、同步荧光光谱及共振散射光谱等方法,探讨了小分子染料与DNA的相互作用机理,并进一步考察了p H、表面活性剂、离子强度、不同溶剂及环糊精(β-CD)对其结合性质的影响,这一类研究对寻找合适的生物探针有重要的指导意义。     

红外光谱法对氨纶中溶剂残存率的快速分析

利用四氯乙烯对干法纺氨纶中残留溶剂进行萃取,采用液体池法进行红外光谱测试,选取特征吸收峰1690 cm-1或1665 cm-1为分析对象,用吸光度的相对峰高进行定量分析,建立了一种用傅里叶变换红外光谱快速定性、定量分析氨纶中溶剂(二甲基甲酰胺或二甲基乙酰胺)残存率的方法。由标准曲线可知:溶剂含量与红外光谱特征峰处吸光度的相对峰高有很好的线性关系,相关系数达0.999以上;样品定量检测的相对标准偏差约为0.4%,加标回收率约为97%;检测效率高,从制样到检测出结果仅需20 min左右。     

Characterization of sterols by gas chromatography-mass spectrometry of the trimethylsilyl ethers

The utility of combined gas chromatography-mass spectrometry in the analysis and characterization of sterols has been explored. Methylene unit (MU) values and principal mass spectrometric data are presented for trimethylsilyl ethers of 28 sterols, including the major natural sterols. The diagnostic value of the fragmentation of trimethylsilyl ethers of Δ⁵-3 β-hydroxysteroids has been confirmed. Characteristic fragmentations of Δ⁴-3 β-trimethylsilyloxysteroids, and of Δ^5,7-3 β-trimethylsilyloxysteroids were also found. Location of side-chain hydroxyl groups is facilitated by the α-cleavages typical of the trimethylsilyl ethers. Fragmentations of saturated sterols, and of Δ⁷, Δ⁸⁽⁹⁾ and Δ⁽¹⁴⁾ stenols, are less influenced by trimethylsilyl ether formation, but the derivatives still afford satisfactory mass spectra. The combination of gas chromatographic and mass spectrometric information allows positive identification of any of the sterols examined, whereas application of either technique alone may give inconclusive results.     

Direct pyrolysis mass spectrometry of chlorine-containing polymers using capillary GC/MS

A direct pyrolysis mass spectrometric technique has been developed and applied to several chlorine-containing polymers. The capillary column in the gas chromatograph has been replaced by uncoated fused silica tubing to avoid the problem of column degradation induced by the polymer pyrolyzates. Under appropriate conditions, the pyrolysis mass spectra were found to be highly reproducible and to serve as “fingerprints.” The technique can be readily applied to carbon-black-filled, crosslinked elastomers, as well as polyblends and composites. The quantitative aspects of the technique have also been addressed.     

Surface modification of halogenated polymers. 6. Graft copolymerization of poly(tetrafluoroethylene) surfaces by polyacrylic acid

Polyacrylic acid can be grafted onto polytetrafluoroethylene (PTFE) once the latter has been reduced locally by an electrode. Two reduction treatments are performed either by direct contact of an electrode or by scanning electrochemical microscopy (SECM) leading to disc shaped reduced zones of, respectively, ∼1 mm and ∼100 μm diameter. Deactivation of reduced PTFE zones by air or oxidant exposure yields unsaturations on the polymeric surface that are prone to graft copolymerization. The grafted polymer, polyacrylic acid, is a cation exchanger that can complex to a fluorescent and reducible cation such as toluidine blue. Desorption of the cation from the polymeric film is characterized using UV-visible, fluorescence spectroscopies and also SECM. The latter technique is used to study the desorption kinetics, which is interpreted by a model taking into account the slow diffusion of the cation inside the membrane. The mean thickness of the film, which is initially ∼100 nm is about the same after one year of air exposure, which emphasizes the stability of the film with time.     

氨苄西林质谱解析及其离子化方式研究

通过对于氨苄西林正离子模式质谱谱图的解析,探讨了氨苄西林的离子化方式和裂解规律。研究表明：氨苄西林存在3种质子化方式,不同的质子化方式所形成分子离子具有不同的裂解方式;质子化的质子具有明显的活性,是质谱进一步裂解的主要原因;离子化方式对于质谱峰的丰度会产生重要影响。本研究为氨苄西林质谱分析和构效关系研究提供了重要的实验基础与理论依据。     

MALDI-TOF-MS: Eine neue analytische Technik zur Charakterisierung von Produkten auf Basis nachwachsender Rohstoffe

MALDI-TOF-MS: A new analytical technique for characterizing products on the base of renewable resources. For the ionization of non-volatile highly polar or high-mass substances a new mass spectrometric technique, the Matrix Assisted Laser Desorption and Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) has been established which is very suitable for the analysis of oligomeric or polymeric substances synthesized on the base of renewable materials. In the following article the new method is introduced and its performance is demonstrated by examples of surfactants and emulsifiers.     

层状铌酸盐MxNb6O17（M=K，Fe，Ni）的合成及对甲硫醇的吸附与光催化性能研究

通过水热合成法合成了具有典型层状结构的MxNb6O17采用离子交换法制备了Ni2Nb6017和Feo75Nb6O17。采用X-射线粉末衍射（XRD）、紫外．可见漫反射光谱（UV-vis-DRS）等技术对催化剂进行表征。通过红外光谱技术考察了催化剂对甲烷气中甲硫醇的吸附性能与光催化氧化性能。结果表明,MxNb6O17及改性后的铌酸盐均具有很好的层状结构,改性后的铌酸盐对光谱的吸收由紫外光区向可见光区域移动,且吸收强度增加。在流动体系中对甲烷气中的甲硫醇具有吸附活性,在静态条件下经紫外光辐射对甲硫醇具有光催化氧化活性。     

Modern mass spectrometry for coatings

For the analysis of polymers soft ionization mass spectrometry, in which only molecular ions are observed, can provide the complete distribution of chains (length, composition, end-groups) in under ten minutes on microgram quantities of material. Moreover, molecular ion information of neat organic pigments or those present in crosslinked networks can also be furnished. No other analytical technique can supply these data in such a short time. The application of mass spectrometry to the characterization of materials used in today's high performance automotive coatings is presented. These include functional monomers, several acrylic copolymers, organic pigments and an epoxide prepolymer. While there are a variety of mass spectrometric techniques, in this paper we will highlight the techniques that we have found useful for the characterization of organic coating components. The selection of the mass spectrometric technique is dictated by the molecular weight of the material and to a lesser extent the chemical composition. We used potassium ionization of desorbed species (K⁺IDS) performed on a quadrupole mass spectrometer for materials under 1000 Daltons (Da). However, many of the ingredients used in current automotive finishes fall between 1000 and 10 000 Da. For these materials we used a Fourier transform mass spectrometer (FTMS) which is well suited for this mass range and boasts the highest resolution and mass accuracy available. Direct desorption/ionization using a carbon dioxide laser is our standard method of sample introduction. Recently, we coupled a gel permeation chromatograph to our FTMS using an electrospray ionization interface. This hyphenated technique offers one of the most powerful characterization methods for the coatings chemist.     

Mass Spectrometric Identification of Proteins Enhanced by the Atomic Force Microscopy Immobilization Surface

An approach to highly-sensitive mass spectrometry detection of proteins after surface-enhanced concentrating has been elaborated. The approach is based on a combination of mass spectrometry and atomic force microscopy to detect target proteins. (1) Background: For this purpose, a technique for preliminary preparation of molecular relief surfaces formed as a result of a chemical or biospecific concentration of proteins from solution was developed and tested on several types of chip surfaces. (2) Methods: mass spectrometric identification of proteins using trailing detectors: ion trap, time of flight, orbital trap, and triple quadrupole. We used the electrospray type of ionization and matrix-assisted laser desorption/ionization. (3) Results: It is shown that when using locally functionalized atomically smooth surfaces, the sensitivity of the mass spectrometric method increases by two orders of magnitude as compared with measurements in solution. Conclusions: It has been demonstrated that the effective concentration of target proteins on specially prepared surfaces increases the concentration sensitivity of mass spectrometric detectors—time-of-flight, ion trap, triple quadrupole, and orbital ion trap in the concentration range from up to 10⁻¹⁵ M.     

Nanophotothermolysis of Poly-(vinyl) Alcohol Capped Silver Particles

Laser-induced thermal fusion and fragmentation of poly-(vinyl) alcohol (PVA)-capped silver nanoparticles in aqueous medium have been reported. PVA-capped silver nanoparticles with an average size of 15 nm were prepared by chemical reduction technique. The laser-induced photo-fragmentation of these particles has been monitored by UV-visible spectroscopy and transmission electron microscopy. The morphological changes induced by thermal and photochemical effects were found to influence the optical properties of these nanoparticles.     

Separation and identification of phospholipid peroxidation products

The molecular species in mixtures of phospholipid hydroperoxides are difficult to separate and identify by typical chromatographic and mass spectrometric techniques. As reported by Havrilla and coworkers, silver ion coordination ionspray mass spectrometry (CIS-MS) has proven to be a powerful technique for the identification of mixtures of hydroperoxides. This ionization technique, which involves the formation of Ag⁺ adducts of the hydroperoxides, provides valuable, unambiguous structural information about the hydroperoxides. Herein, we report a method for the analysis and identification of phospholipid hydroperoxides using CIS-MS. We also report an improved method for the separation of phospholipid hydroperoxides by reversed-phase high-performance liquid chromatography (RP-HPLC), which, for the first time, separates some of the hydroperoxide isomers. CIS-MS can be coupled with this RP-HPLC method by the addition of AgBF₄ to the mobile phase or to the HPLC effluent postcolumn, thus allowing powerful HPLC-MS techniques to be used to identify complex mixtures of phospholipid hydroperoxides.