Kinetic Spectrophotometric Determination of Ritodrine Hydrochloride in Dosage Forms

A simple and sensitive kinetic method was developed for the determination of ritodrine hydrochloride in pharmaceutical preparations. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permenganate at room temperature for a fixed 12.5 min; the absorbance of the colored permenganate ion was measured at 609 nm. The absorbance concentration plots were rectilinear over the range of 1.6–11.2 μg mL^?1 (r = 0.9992) with a minimum detectability of 0.096 μgmL^?1 (2.88 × 10^?7 M). The different experimental parameters affecting the development and stability of color were carefully studied and optimized. The determination of ritodrine hydrochloride by the fixed concentration and rate constant methods is also feasible with the calibration equations obtained, but the fixed time method has been found to be more applicable. The proposed method was applied successfully to the determination of ritodrine hydrochloride in tablets and ampoules with average recoveries of 100.37 ± 0.93% and 100.42 ± 0.87%, respectively. The results obtained were in good agreement with those obtained using a reference method for comparison. A proposal of the reaction pathway is also presented.     

Structural investigations on zirconium phosphate-phosphite and on itsn-butylamine intercalate

Zirconium phosphate-phosphite have various structure belonging to the drying heat of the sample. While sample dried above sat. NaCl solution had interlayer distance of 1.30 nm (result fromd ₁=0.74 nm andd ₂=0.56 nm for phosphite layer), the sample dried under IR lamp on air having interlayer spacingd=0.74 nm charactderistic for -Zr(HPO₄)₂·H₂O containing little amount of phosphite groups. The composition of the first sample can be characterized by chemical formula, as Zr(HPO₄)_0.7(HPO₃)_1.3· ·0.5H₂O. The X-ray powder diffraction data ofn-butylamine intercalate suggest that in the process take place only the phosphate region of zirconium phosphate-phosphite (ZrPP).     

Using fluorescence resonance energy transfer to measure distances along individual DNA molecules: corrections due to nonideal transfer

Single molecule fluorescence resonance energy transfer has been extensively used to measure distance changes and kinetics in various biomolecular systems. However, due to complications involving multiple de-excitation pathways of the dyes, the absolute inter-dye distance information has seldom been recovered. To circumvent this we directly probe the relative variations in the quantum yield of individual fluorophores. B-DNA was used as a scaffold to position the donor (Cy3 or TMR) at precise distances from the acceptor (Cy5) within the Forster radius. We found that the variation in the Cy3 quantum yield is approximately 5 times larger than that of TMR. By taking into account the molecule-to-molecule variability in the acceptor/donor quantum yield ratio, the apparent fluorescence resonance energy transfer efficiencies were scaled to yield the theoretical values. We obtained very good agreement with a physical model that predicts distances along B-DNA.     

Synthesis and reactions of 3-thioxo[1,2,4]-triazino[3,2-b]quinazolin-10-ones

Thiation of [1,2,4]triazino[3,2-b]quinazoline-3,10-dione 1 proceeds selectively to give the 3-thioxo-analog 3 . The latter was converted to the corresponding 3-methylthio derivative 4 which was reacted with aniline and hydrazine to give the corresponding anilino- and hydrazino derivatives 5 and 7 . Compound 7 was converted to the hydrazones 8a,b and into the novel heterocyclic ring systems [1,2,4]triazolo[4′,3′:4,5][1,2,4]triazino-[3,2-b]quinazolin-7-ones 9, 10a,b and tetrazolo[1′,5′:4,5][1,2,4]triazino[3,2-b]quinazolin-7-one 11 .     

Bioactive Penta-Coordinated Diorganotin(Iv) Complexes of Pyridoxalimine Schiff Bases

Abstract

Diorganotin(IV) complexes of an extended system derived from the condensation of pyridoxal hydrochloride with 2-amino phenol (H₂L¹), 2-amino-4-methyl phenol (H₂L²), 2-amino-4-chloro phenol (H₂L³), 2-amino-4-nitro phenol (H₂L⁴), 1-amino-2-naphthol hydrochloride (H₂L⁵) have been synthesized by the reaction of dichlorodiorganotin(IV) in a 1:1 molar ratio with these ligands. Spectral studies (IR, ¹H, ¹³C, ¹¹⁹Sn NMR) along with physical data evidenced the formation of penta-coordinated species with the ligands acting as tridentate (ONO) with oxygen occupying the axial positions, and nitrogen at one of the equatorial positions. The ligands and their organotin complexes have been evaluated for antimicrobial activity against phytopathogenic fungi Candida albicans and Aspergillus niger at 25 ± 1 °C and bacteria Bacillus subtilis, Escherichia coli, and Staphylococcus aureus at 37 ± 1 °C. The activities of the ligands have been enhanced on complexation and the results indicate that they exhibit significant antimicrobial properties.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Preparation and Characterization of Poly Vinyl Alcohol/Poly Vinyl Pyrrolidone/Clay Based Nanocomposite by Gamma Irradiation

A series of PVA/PVP/clay nanocomposite were prepared by gamma irradiation with different clay contents of (0.15, 0.3, 1, 1.5, 3 and 5 wt%). The gelation content and swelling behavior were investigated. The morphology and structure of PVA/PVP/clay nanocomposite and dispersion of the clay nanoparticles in the polymeric matrix were examined by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The introduction of clay into polymeric matrix was investigated by X-ray diffraction pattern (XRD) and Transmission electron microscope (TEM). It is observed that, the increase of the clay content causes a decrease in the swelling percent. The thermal stability studies confirmed that the introduction of clay lead to an increase in the thermal stability. The TEM results showed that the clay nanoparticles are interchelated or exfoliated in the polymeric matrix. Some desirable characteristics such as relatively good swelling and excellent barrier capability against microbe penetration suggested that PVA/PVP/clay nanocomposite can be a good candidate as a wound dressing.     

Eigenvalues of the two-dimensional Schrödinger equation with nonseparable potentials

The energy eigenvalues of coupled oscillators in two dimensions with quartic and sextic couplings have been calculated to a high accuracy. For this purpose, unbounded domain of the wave function has been truncated and various combination of trigonometric functions are employed as the basis sets in a Rayleigh-Ritz variational method. The method is applicable to the multiwell oscillators as well. © 1996 John Wiley & Sons, Inc.     

A contribution to the evaluation of REE in an Egyptian phosphate deposit

Results are presented of ICP-AES determinations of 13 rare earth elements (REE), Sc and Y in 47 core samples of 10 bore holes in the phosphate deposit of the Abu-Tartur area, Western Desert, Egypt. The complete dissolution of the samples was achieved by digestion with HF/HNO₃/HCl in a closed PTFE decomposition vessel. Such analytical lines were selected that showed no spectral interferences from the major constituents of the phosphate samples or from other REE in the samples. The precision for the determination of the individual elements for the whole procedure ranges from 0.8% to 4.0%. Also, smooth normalized chondrite and shale patterns were obtained. The results revealed that the total REE content in the investigated samples was between 0.8 and 2 mg/g, which is remarkably high when compared with many phosphate deposits in other parts of the world. The results also showed that the concentrations of individual REE as well as their total concentrations in the samples follow their P₂O₅ content, indicating that the REE may be accumulated within the phosphate fraction of the phosphate bearing sediments.Presented at the Rare Earth Minerals Conference, London (UK), April 1 and 2 (1993)     

Spectra of europium-doped yttrium oxide and yttrium vanadate phosphors

The spectral distributions of the visible absorption and fluorescence emission under electron beam excitation of Eu³⁺-doped (Y₂O₃) and (YVO₄) powders have been detected and analyzed. (Y₂O₃: Eu³⁺) has a cubicC crystal structure with a unit cell dimension a=10·61 Å. Its observed transitions from⁷ F ₀ to many upper states have been recognized; the observed number of Stark components is in agreement with that based on theC ₂ site symmetry of the Eu³⁺ ion in Y₂O₃. Eu³⁺-doped yttrium vanadate has a typical zircon tetragonal crystal structure with unit cell dimensions ofc=6·29 Å anda=7·11 Å. The observed transitions in (Eu³⁺: YVO₄) have been identified and assigned in accordance with theD _2d site symmetry of the Eu³⁺ ion in this lattice.The authors would like to express their deep gratitude to Professor G. F. J.Garlick, University of Hull, England, for offering experimental facilities in his Physics Department.