Determination of the number of light-absorbing species in the protonation equilibra of selected drugs

The determination of the number of components in a mixture is an important tool for qualitative and quantitative analysis in spectroscopy. The accuracy of nine selected indices for an estimation of the number of components that contribute to a set of spectra was critically tested on experimental data sets of protonation equilibria of four drugs using the INDICES algorithm in S-Plus. Methods are classified into two categories: precise methods based on a knowledge of the instrumental error of the sabsorbance data, s_inst(A), and approximate methods requiring no such knowledge. Indices of precise methods predict the correct number of components, even the presence of a minor one, when the quality of data is high and instrumental error is known. Improved identification of the number of species uses the second or third derivative function for some indices, namely when the number of species in the mixture is higher than four and when, due to large variations in the indicator values even at logarithmic scale, the indicator curve does not reach an obvious point where the slope changes. The number of variously protonated components and their dissociation constants for four drugs—mycophenolate, ambroxol, silybin and silydianin—at 25 °C were determined using SQUAD(84) regression and INDICES principal component analysis of the pH-spectrophotometric data. A proposed strategy of efficient experimentation in protonation constants determination, followed by a computational strategy, is presented with the goodness-of-fit tests for various regression diagnostics enabling the reliability of parameter estimates to be accessed.     

蚕茧性别近红外光谱（NIRs）的模式识别

探讨了用近红外光谱识别蚕茧性别的方法和可行性，采用６２５０型近红外光谱分析仪，从波长６８０ｎｍ到１２３５ｎｍ先后对１５０７颗鲜茧做了非破坏性扫描测试，其有效率在９７．２３％～９８．３３％，是目前蚕茧性别鉴别中效果最好的一种方法。结果还表明，这种判别法不受品种、蚕期及年份的影响，而雌雄茧在近红外光谱上表现的差别主要是由蚕蛹的性质不同所致，与茧层关系不大     

单波长紫外可见分光光度计测定药物的导数吸收光谱

建立单波长紫外可见分光光度计测定药物导数吸收光谱的方法。以较小的波长差连续测定药物在不同波长λ处的吸光度A,得到一系列A-λ数据,对该系列数据进行数学处理,分别计算Δλ、ΔA、ΔA/Δλ、Δ2A/Δλ2、Δ3A/Δλ3,分别以ΔA/Δλ、Δ2A/Δλ2和Δ3A/Δλ3等各阶导数为纵坐标,以λ为横坐标,绘制药物的一阶、二阶或三阶导数吸收光谱。采用本方法测定并绘制了维生素A、布洛芬两种药物的一阶、二阶及三阶导数吸收光谱,并与其常规吸收光谱进行对比,表征了药物导数吸收光谱的特性。本方法测定药物的导数吸收光谱,扩大了单波长紫外可见分光光度计的应用范围和分析功能,实现了在单波长紫外可见分光光度计上测定药物导数吸收光谱。     

原子吸收分光光度计用于分子吸收分析测定磷的研究

应用钙元素空心阴极灯中钙元素的４２２．７ｎｍ谱线和原子吸收分光光度计，对磷钒钼黄体系进行了研究，并对生铁样品中磷的含量进行了测定，获得满意的结果。     

Colorimetric technique for the detection of carbofuran and its application in various environmental samples

A large variety of pesticides have been used in the agriculture area to raise the quality, extend and yield storage life of crops. The nonstop uses of these pesticides have resulted in pollution of the environment and also caused risk to human health. For the rapid detection of selective CBFpesticide, we developed a simple and sensitive colorimetric detection method based on azo-coupling reaction. After a simple pre-treatment of carbofuran (2, 2-dimethyl-2, 3-dihydro-7-benzofuranyl N-methyl carbamate) (CBF) (1000 ​μg ​mL⁻¹) with a diazotized solution, the resulting is rapidly undergoing azo-coupling reaction with p-aminoantipyrine (1% alcoholic) with a dramatic color change only in few minutes. Finally, we successfully applied the concentrations of CBF pesticide on vegetable, fruit, soil, and water samples in the presence of natural interferences using UV–Vis spectrophotometer and FTIR with limits of detection at 0.004μgmL⁻¹. CBF had recoveries in the range of 93–98%, with relative standard deviation values less than 2% and good linearity was achieved with r ​≥ ​0.98. The inhibition rate was linear with CBF concentration in the range of 1μgmL⁻¹ to 10μgmL⁻¹. The proposed method applies to analyze CBF pesticide in real samples. FTIR technique was used to consider and gain structural information about the existing intermolecular interactions for vegetable samples.     

Spectrophotometry Determination of Amitriptyline-HCl in Pure and Pharmaceutical Preparations.

ABSTRACT

Amitriptyline-HCl reacts with ammonium molybdate in concentrated sulphuric acid after heating for 20 min. at 100°C to give a green colour having maximum absorbance at 660 nm. The reaction is selective for amitriptyline with 0.01 mg/10ml as visual limit of identification and provides a basis for a new spectrophotometric determination. The reaction obeys Beer's law from 0.01 mg to 1.4 mg/10ml of amitriptyline-HCl and the relative standard deviation is 0.35%. The quantitative assessment of tolerable amount of other drags is also studied.     

Growth, structural and optical properties of CdxZn1−xS thin films deposited using spray pyrolysis technique

Cd_xZn_(1−x)S (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) thin films were deposited by the chemical spray pyrolysis technique using a less used combination of chemicals. Depositions were done at 573 K on cleaned glass substrates. The composition, surface morphology and structural properties of deposited films were studied using EDAX, SEM and X-ray diffraction technique. XRD studies reveal that all the films are crystalline with hexagonal (wurtzite) structure and inclusion of Cd into the structure of ZnS improved the crystallinity of the films. The value of lattice constant ‘a’ and ‘c’ have been observed to vary with composition from 0.382 to 0.415 nm and 0.625 to 0.675 nm, respectively. The band gap of the thin films varied from 3.32 to 2.41 eV as composition varied from x = 0.0–1.0. It was observed that presence of small amount of cadmium results in marked changes in the optical band gap of ZnS.     

Biosynthesis of silver nanoparticle using flowers of Calotropis gigantea (L.) W.T. Aiton and activity against pathogenic bacteria

Silver nanoparticles (AgNPs) from silver nitrate solution are carried out using the flower extract of Calotropis gigantea. Silver nanoparticles were characterized by UV–vis spectrophotometer, X-Ray diffractometer (XRD). Reduction of silver ions in the aqueous solution of silver during the reaction was observed by UV–vis spectroscopy. Crystalline nature of synthesized silver nanoparticles was studied by XRD pattern, refraction peak using the Scherrer’s equation. Antibacterial activity of the silver nanoparticles was performed by disc diffusion method against Bacillus subtilis, Pseudomonas putida and Escherichia coli. The antibacterial activity of synthesized silver nanoparticles by flower extract of C. gigantea was found against B. subtilis (10 mm). Synthesised AgNPs has the efficient antibacterial activity against Gram positive bacteria.     

PBO的合成、表征及磷含量的测定

以4,6-二氨基-1,3-苯二酚盐酸盐和对苯二甲酸为原料,多聚磷酸为介质,缩聚得到聚对苯撑苯并二噁唑(PBO).通过实验得到最佳条件:聚合反应在减压及氮气保护下进行,聚合温度100℃~180℃,控制最终w(P2O5)=83%~84%.通过红外光谱、热重分析对PBO进行了表征.结果表明,合成的PBO具有优良的耐热性能.采用分光光度法测定聚合物中残余的磷含量,测定了最大吸收波长、绘制了磷标准曲线、考察了回流时间对聚合物中残余磷含量的影响.实验结果表明硫酸为溶剂、测定波长710 nm、当聚合物在水中回流30 h后,磷含量≤0.12%.     

Sedimentary siloxanes: A depositional history

A Puget Sound sediment core has been quantitatively analyzed for organic silicon content, as derived from post-1945 release of poly(organo)-siloxanes (silicones). The sedimentary silicone data record and preserve at depth, a smeared event horizon, or first appearance of silicone in the sediment column. Core samples older than 50 years showed no detectable silicone as measured by a new procedure utilizing inductively coupled plasma (ICP) emission spectroscopy after solvent extraction to collect the silicone from gram-sized sediment core samples.