A study of host-guest complexation between amodiaquine and native cyclodextrin. Characterization in solid state and its in-vitro anticancer activity

Amodiaquine (AQ) has been used widely as an antimalarial drug. Amodiaquine is a mannich base 4-amino quinolone with a mode of action similar to that of chloroquine. The inclusion complex of AQ with β-Cyclodextrin (β-CD) in solution phase is studied from the ground and excited state with UV-Visible and fluorescence spectroscopy, respectively. A binding constant and stoichiometric ratio between AQ and β-CD are calculated by BH equation. The solid complexes are prepared by physical method (PM), kneading method (KM) and co-precipitation method (CP). The solid complex is characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and powder X-ray diffraction. The CP method gives the solid product with a better yield than that of physical mixture and KM products. The orientation and structure of the complex are proposed based on the analysis of Patch-Dock server. The anticancer activity also performed for pure AQ and their complex with β-CD. It is clearly shown that an improvement of anticancer activity of AQ while forming complex with β-CD. The solid inclusion complex behaves as the better anticancer ability than AQ alone.     

超细Ir催化剂对氨氧化的电催化性能

报道了一种新型的、用NH4F作络合剂的络合还原法制备的Ir催化剂及其对氨氧化的电催化性能. 结果表明, 由于溶液中的Ir3+和NH4F形成络合物, 因此用这种络合法制得Ir催化剂中Ir粒子的平均粒径为2.8 nm, 要比不加络合剂时制得的Ir催化剂中Ir粒子的平均粒径(7.5 nm)小很多. 所以, 用络合还原法制得的Ir催化剂对氨氧化的电催化活性和稳定性都比不加络合剂时制得的Ir催化剂好很多. 且该制备方法简单、实用, 适用于催化剂的实际生产.     

Colour reaction of scandium with quercetin and its application to the analysis of scandium

A spectrophotometric study of the scandium-quercetin complex is described; μg amounts of scandium can be determined with quercetin at 43.5 mμ and pH 4.4. A 1:1 complex is formed. The apparent instability constant of the complex was estimated as 2.7·10^-7 by a spectrophotometric method. An ion-exchange method for separating scandium from several interfering ions is described.     

甲基绿褪色分光光度法测定红霉素

建立了褪色分光光度法测定红霉素肠溶片中红霉素含量的方法。用二次石英蒸馏水为溶剂,甲基绿和红霉素在40℃下可以反应形成稳定的离子缔合物,以试剂空白做参比测定离子缔合物溶液的吸光度,离子缔合物的生成导致吸收光谱发生变化,且在一定范围内吸光度变化值ΔA与红霉素的浓度成正比,红霉素的浓度在0.000 6~0.105 0mg/mL范围内服从Beer定律,在635nm处测得ε=4.23×104 L/(mol·cm)-1,方法检出限达到0.26μg/mL。方法简便快捷,重现性和选择性好,可用于红霉素肠溶片中红霉素含量的测定。     

Validation of a new method for spectrophotometric determination of polyethylenimine

A new method of determination of polyethylenimine (PEI) is presented. The method is fast, reliable, and easy to perform. It is based on a creation of a complex between Cu²⁺ and PEI and its absorption in UV–VIS spectrum. The complex has a distinct absorption peak in UV part of electromagnetic spectrum and the measurement is optimal at 285 nm. A method is thoroughly analyzed in various concentrations of both PEI and Cu²⁺, temperatures, times of creation of a complex, ionic strengths, background electrolytes types, and pH values. Analytical parameters of the presented method such as linearity, sensitivity, limit of detection (LOD), limit of quantification (LOQ), repeatability, and intermediate precision were also determined.     

Nanoscale analysis of pharmacologically active catechins in body fluids by HPLC using borate complex extraction pretreatment

A pretreatment method based on borate complex formation is described for the selective and simultaneous quantitation of pharmacologically active catechins in human plasma and saliva. This method is based on the interaction of catechins with diphenylborate (as a complexing agent) and tetra-n-butylammonium (as a counter ion) in alkaline media to give the catechin-diphenylborate complex and ion-pair that are extractable to the organic phase. The complex extracted in an organic solvent is dissociated by shaking with an aqueous trifluoroacetic acid solution to back-extract free catechins to the aqueous phase, followed by high-performance liquid chromatography (HPLC) analysis with fluorometric and diode array detection. Under optimal conditions, all catechins originating from green tea extracts were selectively purified from plasma and saliva samples, and they were stabilized during the extraction procedures by forming the complex. The nano-scale quantitative analysis of eight catechins was achieved with high recovery and analytical reproducibility. The proposed method would be a useful tool for pharmacokinetic studies of catechins in plasma and saliva.     

Simultaneous spectrophotometric determination of molybdenum and selenium,and of molybdenum and tellurium

A method is reported for the extraction of molybdenum-phenylfluorone by chloroform. The extraction is complete whether perchlorate ions are present or not but the extractions in the presence of perchlorate ions gave a somewhat more sensitive procedure for the spectrophotometric determination of molybdenum in the solvent phase as the molybdenum-phenylfluorone complex.A procedure is reported for the simultaneous determination of molybdenum and selenium, and molybdenum and tellurium. The method involves first the formation and solvent extraction of the molybdenum-phenylfluorone complex by chloroform in the presence of perchlorate ions, followed by determination of selenium in the remaining aqueous phase as selenium-diethyldithiocarbamate complex after solvent extraction with 2-ethyl-1-hexanol in the presence of perchlorate ions. A similar procedure is reported for the simultaneous determination of molybdenum and tellurium except that in the determination of molybdenum, the phenylfluorone complex is extracted by chloroform in the absence of perchlorate ions. Tellurium is determined in the remaining aqueous phase as tellurium-diethyldithiocarbamate complex after solvent extraction by 2-ethyl-1-hexanol solvent extraction in the presence of perchlorate ions.     

A new graphic method for differentiating mononuclear and polynuclear complexes and for determining their stability constants

A new graphical method is proposed for differentiating mononuclear and polynuclear complexes as well as for determining the stability constant of any complex A(m)B(n). The method is based on the effect of dilution on the degree of dissociation of the complex. The resultant mathematical equation provides a simple graphical calculation which leads to the determination of the stability constant and also the molar absorptivity of the complex.     

Direct decomposition of three-way arrays using a non-negative approximation

Non-negative matrix approximation (NNMA) has been used in diverse scientific fields, but it still has some major limitations. In the present study a novel trilinear decomposition method, termed three-way NNMA (TWNNMA), was developed. The method decomposes three-way arrays directly without unfolding and overcomes the restriction of locking zero elements in the deduced multiplicative update rules by adding a positive symmetric matrix. Direct trilinear decomposition was used as the TWNNMA initialization method and experimental results confirm that this greatly accelerated the convergence. An obvious advantage of TWNNMA is the uniqueness of the non-negative solution, which facilitates a better understanding of the underlying physical realities of complex data. TWNNMA was applied in complex systems such as chemical kinetics, second-order calibration and analysis of GC-MS data. The results demonstrate that TWNNMA, differing from previous trilinear decomposition methods, is comparable to existing second-order calibration methods and represents a promising resolution method for complex systems.     

A rapid and sensitive extractive spectrophotometric determination of copper(II) in pharmaceutical and environmental samples using benzildithiosemicarbazone.

Benzildithiosemicarbazone (BDTSC) is proposed as a sensitive and selective analytical reagent for the extractive spectrophotometric determination of copper(II). BDTSC reacts with copper(II) in the pH range 1.0-7.0 to form a yellowish complex. Beer's law is obeyed in the concentration range 0.5-0.4 microg cm(-3). The yellowish Cu(II)-BDTSC complex in chloroform shows a maximum absorbance at 380 nm, with molar absorptivity and Sandell's sensitivity values of 1.63 x 10(4) dm3 mol(-1) cm(-1) and 0.00389 microg cm(-2), respectively. A repetition of the method is checked by finding the relative standard deviation (RSD) (n = 10), which is 0.6%. The composition of the Cu(II)-BDTSC complex is established as 1:1 by slope analysis, molar ratio and Asmus' methods. An excellent linearity with a correlation coefficient value of 0.98 is obtained for the Cu(II)-BDTSC complex. The instability constant of the complex calculated from Edmond and Birnbaum's method is 7.70 x 10(-4) and that of Asmus' method is 7.66 x 10(-4), at room temperature. The method is successfully employed for the determination copper(II) in pharmaceutical and environmental samples. The reliability of the method is assured by analyzing the standard alloys (BCS 5g, 10g, 19e, 78, 32a, 207 and 179) and by inter-comparison of experimental values, using an atomic absorption spectrometer.     

The determination of microgram quantities of fluoride : The use of the aluminium-haematoxylin complex

This paper describes a method for the spectrophotometric determination of fluoride. The fluoride is separated from interfering ions by the standard method of distillation as hydrofluosilicic acid. The fluoride in this distillate is determined by its destruction of the aluminium-haematoxylin complex; the amount of complex destroyed which is directly proportional to the concentration of fluoride is measured spectrophotometrically using radiation of 5700 A. The method will detect down to 0.05 p.p.m. of fluoride on a 10 gram sample with precision of rather better than ± 10% with larger amounts of fluoride. references p. 368.     

Scattering in view of the Titchmarsh–Weyl theory

The Titchmarsh–Weyl theory for a singular second-order differential equation is presented. The equations, however, are arranged such that the theory is immediately applicable to the multichannel formulation. The mathematical basis of the Titchmarsh–Weyl theory (TWT) is outlined and the Titchmarsh–Weyl m function is presented. Relations to the associated Green's function and the spectral function are given. It is shown how some quantities common in scattering theory can be expressed in terms of the TWT. The method of complex rotation is then applied to the TWT to create a complex rotated analog of the Titchmarsh–Weyl theory. This is then extended as exterior complex scaling is introduced. An outline of a proof for the method of exterior complex scaling is presented and some numerical results of the complete theory are given.     

The Binding of Cu(II) and Zn(II) Ions by Heparin

Abstract

A method is described for measuring the ion binding capacity of heparin. The method is based on the separation of the zinc or copper complex of heparin by gel permeation. It was found that the number of the cation per average molecule of heparin depends on the pH and on the initial concentration of metal cation in solution. The absorption spectrum of heparin-Cu complex is described. The molar absorptivity of this complex is determined, as is the complex formation constant.     

Spectrophotometric determination of some aromatic amines

A method for spectrophotometric determination of four aromatic amines is described. The method is based on the reaction between the amine and the colorless Fe(III)-ferrozine complex. The amine reduces iron from Fe(III) to Fe(II) which forms a violet colored complex with ferrozine. The method is suitable for to the determination of 1,4-phenylenediamine, 2,4-diaminotoluene, 8-aminoquinoline and 2-amino-3-hydroxypyridine. The effect of different factors such as; pH, stability of the complex, temperature, ferrozine concentration, Fe(III) concentration and methanol concentration have been studied. The composition of the complex as well as the tolerance amount of other amines have been reported. Maximum absorbance is at 562 nm and Beer's law is obeyed over the ranges 0.17-1.6 ppm for 1,4-phenylenediamine, 0.45-3.7 ppm for 2,4-diaminotoluene, 0.51-3.4 ppm for 8-aminoquinoline and 0.53-4.4 ppm for 2-amino-3-hydroxypyridine. The obtained molar absorbtivities were 4.7x10(4), 2.0x10(4), 1.6x10(4), 1.5x10(3) l mol(-1) cm(-1) respectively.     

Spectrophotometric determination of nitrite and nitrate using phosphomolybdenum blue complex

A method for spectrophotometric determination of nitrite and nitrate is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phosphomolybdenum blue complex is oxidized by the addition of nitrite and this causes a reduction in intensity of the blue color. The absolute decrease in the absorbance of the blue color or the rate of its decrease is found to be directly proportional to the amount of nitrite added. The absorbance of the phosphomolybdenum blue complex is monitored spectrophotometrically at 814 nm and related to the concentration of nitrite present. The effect of different factors such as acidity, stability of the complex, time, temperature, phosphate concentration, molybdenum concentration, sodium sulfide concentration and the tolerance amount of other ions have been reported. Maximum absorbance is at 814 nm. The range of linearity using the conventional method is 0.5-2.0 ppm with molar absorptivity of 1.1 x 10(4) l mol(-1) cm(-1). and a relative standard deviation of 2.6% for five measurements. The range of linearity using the reaction rate method is 0.2-3.6 ppm with a relative standard deviation of 2.4% for five measurements. The method is applied for determination of nitrite and nitrate in water, meat products and vegetables.     

气相色谱叠加定量方法的研究

叠加法是由内标法衍生而来的一种气相色谱定量方法。对于较复杂混合物的分析,当选择内标物困难时,用叠加法定量更为方便。本文在大量实验的基础上,提出了叠加法定量过程中应注意的一些问题。     

The determination of microgram quantities of fluoride: The use of the aluminium-eriochromecyanin complex

A spectrophotometric method for determining fluoride using the aluminium-eriochromecyamn complex is described. Fluoride in solutions free from mterfering ions,or obtained by distillation as hydrofluosilicic acid is determined by its destruction of the complex, the amount destroyed being directly proportional to the fluoride content. The method will detect as little as 0.02 μg/ml of fluoride and with 0–20 μg in the final solution fluoride can be determined with accuracy of ± 0.6 μg.A preliminary study of the aluminium-eriochromecyanin-fluoride system, has been carried out and a tentative reaction mechanism suggested.     

Use of modified smooth exterior scaling method as an absorbing potential and its application

Here, we propose a new complex path to achieve better absorption during the propagation of a wavepacket. In the proposed modified smooth exterior scaling (SES) method, scaling function, θ(x), has been chosen as a real function rather than complex (as used in a conventional smooth exterior scaling method). It greatly reduces the artificial reflections from the boundary edges. This modified SES method is applied to study the multiphoton dissociation of H(2)(+) in intense laser field. The resonance states are calculated accurately.     

4-(N,N-diethylamino) benzaldehyde thiosemicarbazone in the spectrophotometric determination of palladium

4-(N,N-diethylamino)benzaldehyde thiosemicarbazone(DEABT) is proposed as a sensitive and selective analytical reagent for the spectrophotometric determination of palladium(II). The reagent reacts with palladium (II) in a potassium hydrogen phthalate-hydrochloric acid buffer of pH 3.0, to form a yellow complex. Beer's law is obeyed in the concentration range up to 3.60 microgmL(-1). The optimum concentration range for minimum photometric error as determined by Ringbom plot method is 0.36 - 3.24 microg mL(-1). The yellow Pd(II)-DEABT complex shows a maximum absorbance at 408 nm, with molar absorptivity of 3.33 x 10(4) dm3 mol(-1) cm(-1) and Sandell's sensitivity of the complex from Beer's data, for D = 0.001, is 0.0032 microg cm(-2). The composition of the Pd(II)-DEABT complex is found to be 1:2 (M:L). The interference of various cations and anions in the method were studied. The proposed method was successfully used for the determination of Pd(II) in alloys, catalysts, complexes and model mixtures with a fair degree of accuracy.     

Thorium complex of 2,7-dinitroso-1,8- dihydroxynaphthalene-3,6-disulphonic acid : Complexometric determination of thorium with ethylenediaminetetraacetic acid

Thorium forms a pinkish-violet coloured complex with dinitrosochromotropic acid, which has been used as an indicator in the titrimetric determination of thorium with EDTA. The method is based on the fact that this coloured complex is less stable than the thorium-EDTA complex and breaks down after a bulk of thorium has reacted with EDTA; this marks the end-point, which is the change from pinkish-violet to red. am little as 3.1 mg of thorium present in 50 ml volume of solution may be accurately determined within a pH range from 2.2 to 3.5. The study of interferences revealed that quite a number of elements do not interfere; iron may be masked with ascorbic acid. Thorium may be determined by the same method, after separating it from many interfering ions by precipitating it with o-anisilic acid.