Extraction and spectrophotometric determination of titanium(IV) with malachite green and p-chloromandelic acid, with application to mild steels

A very sensitive, selective and simple method for extraction and spectrophotometric determination of titanium(IV) with an alpha-hydroxy acid has been developed. p-Chloromandelic acid reacts with titanium in weakly acidic aqueous solution at room temperature to form a complex anion extractable into chlorobenzene with Malachite Green as counter-ion. Titanium is determined indirectly by measuring the absorbance of Malachite Green in the extract at 630 nm. The calibration graph is linear for titanium(IV) over the range 0.25-7.5muM (0.05-1.44 mug); the apparent molar absorptivity is 1.31 x 10(5) l.mole(-1).cm(-1). The method has been successfully applied to the determination of titanium in mild steels.     

A novel and highly sensitive catalytic method with oscillopolarographic detection for the determination of ultratrace amounts of iridium

Iridium(IV) has a strong catalytic effect on the slow redox reaction between Malachite Green and periodate ion in pH 4.2 acetate buffer solution at 100 degrees , and Malachite Green exhibits a sensitive single-sweep oscillopolarographic wave at -0.65 V vs. SCE. This provides the basis for a novel and highly sensitive and selective catalytic method with oscillopolarographic detection for iridium. The effect of pH, potassium periodate and Malachite Green concentrations, reaction temperature and reaction time and other variables are investigated. The detection limit is 8 ng/l. with a fixed-reaction time of 10 min. A linear calibration graph from 24 to 1600 ng/l. is obtained. Possible interferences by co-existing ions are examined.     

Extraction and spectrophotometric determination of molybdenum(VI) with Malachite Green and p-chloromandelic acid

Molybdenum(VI) reacts with p-chloromandelic acid to form a complex extractable into chlorobenzene with Malachite Green, from aqueous solution at pH 2.0-4.0 at room temperature, and can then be determined indirectly by measuring the absorbance of the Malachite Green in the extract, at 630 nm. The calibation graph is linear for molybdenum over the range 0.26-10.0 x 10(-6)M (0.10-4.0 mug); the apparent molar absorptivity is 1.06 x 10(5) l.mole(-1).cm(-1). The method has been applied to the determination of molybdenum in mild steels with satisfactory results.     

Extraction-spectrophotometric determination of some antihistaminic agents with fast green FCF

A rapid, simple, precise, accurate and highly sensitive method for the determination of some antihistaminic agents such as dimethindene maleate (DMM), embramine hydrochloride (EMH), isothipendyl hydrochloride (IPH), mebhydrolin napadisylate (MHn), methdilazine hydrochloride (MDH), promethazine hydrochloride (PMH), trimeprazine tartrate (TMT) and triprolidine hydrochloride (TPH) in bulk samples and pharmaceutical preparations is proposed. The method is based on the formation of a chloroform-soluble ion-association complex between the antihistaminic agent and Fast Green FCF at pH 5.0 with an absorption maximum at 620 nm. The composition of antihistaminic agent and Fast Green FCF in each ion-association complex is studied. The relative standard deviation of the proposed method is less than 1.3%, the percent recovery is 99.4–100.2% and the results are not significantly different from the standard methods at the 95% confidence level.     

A new efficient technique for solving two-point boundary value problems for integro-differential equations

In this paper, we propose a new efficient method based on a combination of Adomian decomposition method (ADM) and Green’s function for solving second-order boundary value problems (BVPs) for integro-differential equations (IDEs). The proposed method depends on constructing Green’s function before establishing the recursive scheme for the solution components. Unlike the ADM or modified ADM , the proposed method avoids solving a sequence of difficult nonlinear equations (transcendental equations) for the unknown parameters. The proposed method provides a direct recursive scheme for obtaining the series solution with easily calculable components. We also provide a sufficient condition that guarantees a unique solution to the second-order BVPs for IDEs. Convergence and error analysis of the proposed method are also discussed. Convergence analysis is reliable enough to estimate the error bound of the series solution. Some numerical examples are included to demonstrate the accuracy, applicability, and generality of the proposed approach. The numerical results reveal that the proposed method is very effective and simple.     

Kinetic determination of traces of manganese in different materials by its catalytic effect on the methylene green-periodate reaction

The oxidation of Methylene Green by sodium periodate is a slow process. A kinetic method based on the catalytic effect of manganese(II) on this reaction in the presence of 1,10-phenanthroline as activator is described. The reaction is followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 620 nm. Under the optimal experimental conditions [4 x 10(-5)M Methylene Green, 0.2M acetate buffer (pH 4), 2 x 10(-3)M 1,10-phenanthroline, 2.5 x 10(-3)M sodium periodate, 35 degrees ], manganese(II) between 0.2 and 30 ng ml is determined by the tangent method. The accuracy of the method and the influence of 44 foreign ions have been studied and an equation for the kinetics of the catalysed reaction is proposed. The procedure has been applied to the determination of manganese in water, milk and beer with excellent results.     

含时密度泛函理论研究低带隙的中性和带电的交替共聚芴的光学特性

用含时的密度泛函（TD—DFT）方法研究了低带隙的中性和带电的交替共聚芴Green 1）,该化合物是由烷染取代芴和（1,2,5-噻吩基-3,4-硫重氮基）喹喔啉噻吩（T—TDQ—T）单元交替重复组成,对他们的激发态特性用二维（2D）和三维（3D）实空间分析方法做了进一步分析．对于中性的Green 1,分别得到其带隙、键能、激子结合能和核驰豫能．用3D跃迁密度方法对中性和带电的Green 1的跃迁偶极矩进行比较可显示出跃迁偶极矩的取向和强度;用3D电荷差异密度方法显示出激发后的中性和带电的Green 1电荷重新分布和比较,用2D实空间分析方法（跃迁密度矩阵）来研究中性和带电的Green 1处于激发态时的电子空穴相干性．中性Green 1的激发态特性分别用TD—DFT和ZINDO两种方法进行了计算,比较得出电子-电子相互作用（在TD—DFT中）对激发态性质的重要影响．     

Catalytic determination of traces of silver(I) using the oxidation of Janus Green with peroxodisulfate.

A method for sensitive and selective determination of silver based on the catalytic effect of silver(I) ion on the oxidation of Janus Green by peroxodisulfate is described. o-Phenanthroline is used as an activator. The rate of the decrease in absorbance of Janus Green (at 615 nm) is proportional to the concentration of silver in the range of 0.3-4.0 ng mL(-1) and 4.0-500.0 ng mL(-1). The theoretical limit of detection was 0.25 ng mL(-1). The method is free from most interferences. The method was applied to the determination of silver in plants (the uptake of silver by plants), in photographic solutions, lake water and several synthetic samples.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定工业废水中的颜料绿58

建立了硝酸溶解-电感耦合等离子体原子发射光谱(ICP-AES)法测定工业废水中颜料绿58的分析方法。方法前处理简单,在选定的条件下,检出限为3.0×10-3 mg/L,方法的相对标准偏差小于3%,样品加标回收率在95.0%~105%。方法准确,快速,可用于水中颜料绿58的定量分析。     

研究激发态的多体格林函数理论

本文介绍的多体格林函数理论是一种建立在一套格林函数(包括单粒子格林函数和双粒子格林函数)方程基础上的,用以研究物质激发态性质的第一性原理方法。该理论包括计算准粒子性质的GW方法和描述电子-空穴对运动的Bethe-Salpeter方程。GW方法可以以很高的精度计算轨道能量、能带结构、准粒子寿命等物理量;Bethe-Salpeter方程则在研究激发能、光吸收谱、激发态动力学等光学性质上有广泛的应用前景。多体格林函数理论通过自能算符描述电子之间以及电子与空穴之间的交换关联作用。本文将详细阐述该理论的基本概念和原理,并对其在各种材料中的应用做简要介绍。     

Label-free fluorescent sensor for mercury(II) ion by using carbon nanotubes to reduce background signal

A simple, selective and sensitive turn-on fluorescent sensor for the detection of mercury(II) ion was developed using Sybr Green I as the signal reporter and SWCNTs as the quencher. Due to the affinity of SWCNTs towards ssDNA and organic dye, Sybr Green I, thymine-rich ssDNA and SWCNTs could form a self-assembly of three components, resulting in fluorescence quenching. Upon addition of another thymine-rich ssDNA and mercury(II) ion, formation of dsDNA via T-Hg(2+)-T base pairs enabled Sybr Green I to intercalate into the dsDNA, resulting in the restoration of fluorescence. SWCNTs were found to reduce the background signal and improve the analytical sensitivity. A linear relationship between the fluorescence intensity and the concentration of mercury(II) ion was observed in the range of 20-1250 nM (R = 0.9985) with a detection limit of 7.9 nM. The proposed method was applied to detect mercury(II) ion in tap water samples with good results.     

Label-Free Fluorescent Aptasensor Based on a Graphene Oxide Self-Assembled Probe for the Determination of Adenosine Triphosphate

A sensitive and selective fluorescent aptasensor for adenosine triphosphate (ATP) was fabricated, composed of unbound SYBR Green I, graphene oxide, and a label-free detection probe. When ATP and complementary DNA of a signal probe were introduced, π-stacking interactions repelled the probe from the graphene oxide and formed a DNA-SYBR Green I duplex structure, triggering an increase in the fluorescence. ATP was determined over a linear range of 10 to 700 nM with a detection limit of 1 nM. The method displayed good selectivity, and is currently the most sensitive ATP fluorescence method. Furthermore, prominent fluorescence signals were also obtained in cellular assays. Consequently, the biosensor may have significant applications in protein, pathogenic microorganisms, and small molecule detection.     

Development and validation of a fast monoclonal based disequilibrium enzyme-linked immunosorbent assay for the detection of triphenylmethane dyes and their metabolites in fish

Malachite Green (MG), Crystal Violet (CV) and Brilliant Green (BG) are antibacterial, antifungal and antiparasitic agents that have been used for treatment and prevention of diseases in fish. These dyes are metabolized into reduced leuco forms (LMG, LCV, LBG) that can be present in fish muscles for a long period. Due to the carcinogenic properties they are banned for use in fish for human consumption in many countries including the European Union and the United States. HPLC and LC-MS techniques are generally used for the detection of these compounds and their metabolites in fish. This study presents the development of a fast enzyme-linked immunosorbent assay (ELISA) method as an alternative for screening purposes. A first monoclonal cell line producing antibodies to MG was generated using a hybridoma technique. The antibody had good cross-reactivates with related chromatic forms of triphenylmethane dyes such as CV, BG, Methyl Green, Methyl Violet and Victoria Blue R. The monoclonal antibody (mAb) was used to develop a fast (20 min) disequilibrium ELISA screening method for the detection of triphenylmethanes in fish. By introducing an oxidation step with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) during sample extraction the assay was also used to detect the presence of the reduced metabolites of triphenylmethanes. The detection capability of the assay was 1 ng g(-1) for MG, LMG, CV, LCV and BG which was below the minimum required performance limit (MRPL) for the detection method of total MG (sum of MG and LMG) set by the Commission Decision 2004/25/EC (2 ng g(-1)). The mean recoveries for fish samples spiked at 0.5 MRPL and MRPL levels with MG and LMG were between 74.9 and 117.0% and inter- and intra-assay coefficients of variation between 4.7 and 25.7%. The validated method allows the analysis of a batch of 20 samples in two to three hours. Additionally, this procedure is substantially faster than other ELISA methods developed for MG/LMG thus far. The stable and efficient monoclonal cell line obtained is an unlimited source of sensitive and specific antibody to MG and other triphenylmethanes.     

Extractive photometric determination of cobalt with acid monochrome green S

Cobalt forms with Acid Monochrome Green S a complex which can be extracted quantitatively into butanol from 1.6M sodium chloride medium at pH 9.5-11.5. The molar absorptivity of the complex is 3.2 x 10(4) at 625 mmu. The method has been used to determine cobalt in gallium metal.     

Membrane Potential Photoresponse of Crowned Malachite Green Derivatives Affording Perfect Photoswitching of Metal Ion Complexation

Photoirradiation effect on potential response to metal ion concentrations and photoinduced potential change were investigated with poly(vinyl chloride) membranes based on a Malachite Green derivative carrying a bis(monoaza-15-crown-5) moiety, by comparing other Malachite Green derivatives. The Malachite Green carrying a bis(crown ether) moiety caused a potential response to potassium ion concentration changes under dark condition. In the membrane potential response, a clear-cut photoinduced switching of potential response was realized by the membrane of Malachite Green carrying a bis(crown ether) moiety, which exhibited no potential response to potassium ion concentrations (0 mV/decade) on UV irradiation. On the other hand, a Malachite Green carrying a monocyclic benzocrown ether moiety showed a considerable dependence of the membrane potential on the metal ion concentrations under both dark and UV irradiation conditions.     

Membrane Potential Photoresponse of Crowned Malachite Green Derivatives Affording Perfect Photoswitching of Metal Ion Complexation

Photoirradiation effect on potential response to metal ion concentrations and photoinduced potential change were investigated with poly(vinyl chloride) membranes based on a Malachite Green derivative carrying a bis(monoaza-15-crown-5) moiety, by comparing other Malachite Green derivatives. The Malachite Green carrying a bis(crown ether) moiety caused a potential response to potassium ion concentration changes under dark condition. In the membrane potential response, a clear-cut photoinduced switching of potential response was realized by the membrane of Malachite Green carrying a bis(crown ether) moiety, which exhibited no potential response to potassium ion concentrations (0 mV/decade) on UV irradiation. On the other hand, a Malachite Green carrying a monocyclic benzocrown ether moiety showed a considerable dependence of the membrane potential on the metal ion concentrations under both dark and UV irradiation conditions.This revised version was published online in July 2005 with a corrected issue number.     

The Pennsylvania Green Fluorophore: a hybrid of Oregon Green and Tokyo Green for the construction of hydrophobic and pH-insensitive molecular probes

[structure: see text] Fluorescent small molecules are powerful tools for exploring cellular biology. As a more hydrophobic, photostable, and less pH-sensitive alternative to fluorescein, we synthesized Pennsylvania Green, a bright, monoanionic fluorophore related to Oregon Green and Tokyo Green. Comparison of membrane probes comprising N-alkyl-3beta-cholesterylamine linked to 4-carboxy-Tokyo Green (pK(a) approximately 6.2) and 4-carboxy-Pennsylvania Green (pK(a) approximately 4.8) revealed that only Pennsylvania Green was highly fluorescent in acidic early and recycling endosomes within living mammalian cells.     

基于核酸适配体-质粒DNA复合物信号放大的荧光免疫传感技术

提出了一种简便、高灵敏的荧光免疫传感新技术,通过抗体/抗原/核酸适配体-质粒DNA复合物的特异性识别与双链质粒DNA与荧光染料SYBR Green Ⅰ的嵌合作用, 实现对血小板衍生增长因子BB(PDGF-BB)的检测.生物识别反应在微孔板中进行,PDGF-BB抗原与微孔板底部预包被的PDGF-BB抗体免疫反应后,加入核酸适配体-质粒DNA复合物与抗原形成夹心复合物.加入DNA双链嵌合染料SYBR Green Ⅰ与夹心复合物的双链DNA部分结合可产生强荧光,其荧光强度可用于定量测定PDGF-BB浓度.实验考察了离子浓度、核酸适配体的延伸引物片段与质粒PUC19的反应比例、染料SYBR Green Ⅰ浓度等分析条件对荧光信号的影响.在优化反应条件下,PDGF-BB检测的线性范围为0.2～200 μg/L,检出限为0.1 μg/L,并且实现了对人血清中PDGF-BB的定量检测.