Rapid Spectrophotometric Assay of Cephradine and its Dosage Forms

Abstract

A new spectrophotometric method to determine cephradine based on its reaction with acetylacetone-formaldehyde reagent (pH 4.3) is proposed. The yellow chromophore shows an absorption maxima at 400 nm, having a molar absorptivity coefficient of 2.59. 10³ L mol^?1 cm^?1. Optimization of the reaction conditions has been investigated. Obediance to Beer's law (0–110 mog per ml) permitted the assay of cephradine in its dosage forms. The method has been compared with the official method and found to be simple, artwrate (t-test) and reproducible (F-test).     

Spectrophotometric Assay of Penem (SCH 29482) by Reaction with Imidazole

Abstract

A rapid method is described for the determination of SCH 29482. This is based on the spectrophotometric measurement at 386 nm of the product of reaction with imidazole formed at 35°Cin a 1.5 M imidazole and 2×10^?3M mercuric chloride solution at pH 7.50. The method, which permits detection of concentrations of SCH 29482 as low as to 2.8, μg/ml, is reproducible and specific for intact SCH 29482 in the presence of degradation products. The molar absorptivity for the chromophore formed is 2.54×l0⁴ I mol^?1cm^?1.     

Spectrophotometric and Spectrofluorometric Determination of Heptaminol and mexiletine in Their Dosage Forms

Abstract

Two simple, rapid specific methods were developed for the determination of heptaminol and mexiletine and their dosage forms. The methods are based on the reaction of either heptaminol or mexiletine with acetylacetone-formaldehyde reagent to give a yellow chromophore measurable spectrophotometrically at 344 or 338 nm or flurometrically at 480 nm for heptaminol and mexiletine, respectively. The color was stable for at least 1/2 h. Beer's law was valid within a concentration range of 15–30 and 8–20 μg ml^?1 spectrophotometrically and 0.2–0.8 and 0.4–1.0 μg ml^?1 fluorometrically for heptaminol and mexiletine, respectively.     

Synthesis of multifunctional copolymers of poly(methylphenylsilane) with (R)-N-(1-phenylethyl)methacrylamide,disperse red 1 methacrylate and their optical and photoluminescence properties

Abstract

We report the synthesis and characterization of multifunctional polysilane copolymers containing chiral and azobenzene chromophore as a pendant group. Multifunctional polymers of poly(methylphenylsilane) (PMPS) with (R)-N-(1-phenylethyl)methacrylamide (R-NPEMAM) and disperse red 1 methacrylate (DR1MA) were synthesized in a quartz tube using UV-technique. The molecular weights of such synthesized copolymers were found to be in the order of 10³. The appearance of two glass transition temperatures in DSC indicated that the synthesized copolymers are block copolymers. The electronic absorbance of synthesized polymers was observed at 272?nm (π-π* transition of aromatic ring), 330?nm (σ-σ* transition of Si-Si chain of PMPS) and 475?nm (n-π* with π-π* transition due to azobenzene chromophore of DR1MA unit). The chirality of the synthesized polymer was confirmed through circular dichroism observed at 261?nm. Induced chirality appeared at 330?nm and 470?nm due to the association of the Si-Si chain of PMPS and the presence of azobenzene chromophore of the DR1MA unit respectively. The photoluminescence (PL) properties of the synthesized copolymers (SCDRDM-1B, SCDRDM-2B, and SCDRDM-3B) were observed at 307?nm and 415?nm when excited at 275?nm. The λem was also observed at 415?nm when excited by 325?nm. The multi-emission spectra appeared at 500?nm, 550 and 590?nm are presumed to be due to exciton coupling between azobenzene chromophore of DR1MA, and Si-Si σ-conjugation in association with the aromatic ring of PMPS and chiral unit R-NPEMAM block.     

NLO active CuII/RuII and CdII/RuII coordination-organometallic complexes: synthesis,structural characterization and photoluminescence properties

Cu^II/Ru^II and Cd^II/Ru^II hybrid complexes [Cu(L_1–3)(NC₅H₄C≡CRu(dppe)₂Cl)] (1a-3a) and [Cd(L_1-3)(NC₅H₄C≡CRu(dppe)₂Cl)] (1b–3b) have been prepared by reaction of trans-[RuCl(dppe)₂(C≡C-py-3)] (1) with copper or cadmium acetate in the presence of Schiff base ligands L_H1–3 (where L_H = 2-(pyrrole-2-yl-methylidine)aminophenol (L_H1), 5-bromo-2-(pyrrole-2-yl-methylidine)aminophenol (L_H2) and 5-nitro-2-(pyrrole-2-yl-methylidine)aminophenol (L_H3)). The hybrid materials were characterized on the basis of elemental analyses, TEM, IR, UV–visible, ¹H NMR, and ³¹P NMR spectral studies. TEM overview observations revealed well-dispersed spherical nanoparticles of ~60 nm are formed. Quasireversible redox behavior is observed for Cu^II/Ru^II complexes corresponding to Cu^I/Cu^II and Ru^II/Ru^III couples. All the complexes exhibit blue-green emission as a result of fluorescence from the intraligand (π → π*) emission excited state with good quantum yield. The second-order nonlinear optical (NLO) properties of Cu^II/Ru^II and Cd^II/Ru^II complexes have been investigated by the Kurtz-powder method. The second harmonic generation efficiency of these complexes show that these complexes are NLO active and display good second-order nonlinear optical activity.     

Synthesis and nonlinear optical properties of donor-acceptor dyes based on triphenylpyrazolines as a donor block and dicyanoisophorone as acceptor

A series of donor-acceptor dyes based on polyfluoro-substituted triarylpyrazolines (as a donor block) and a dicyanoisophorone group (as an acceptor) were synthesized using the Knoevenagel condensation. The dyes have an absorption in the region of 509–514 nm and intense luminescence at 648–663 nm in chloroform with a large Stokes shift (up to 4410 cm^–1). Based on the synthesized dyes, chromophore–polymer (guest–host) films were obtained in a polycarbonate matrix with a chromophore content up to 27 wt.%. Poling of chromophore–polymer films was carried out in an electric field of a corona discharge and the coefficient of nonlinear optical response d₃₃ was measured by the second-harmonic generation method of the fundamental frequency of a Nd-YAG laser (1064 nm). The obtained films have a high initial thermal stability and a nonlinear optical response up to 80 pm V^–1, which persists up to 115 °С.

     

Spectrophotometric Determination of Chlorpromazine and Levomepromazine Hydrochlorides In Injectables and Drops By Reaction With Ferric Ion

Abstract

The principal aim of this research was the standardization of a spectrophotometric method using the reaction with ferric ion for quantitative determination of these substances in pharmaceutical preparations. By reaction with ferric ion chlorpromazine gave a pink compound with maximum absorption at 525 nm. the violet product obtained by the reaction with ferric ion and levomepromazine had a maximum at 565 nm. Beer's law was obeyed in a wide range of concentrations for both compounds. the method was applied to simulated and commercially available samples. the efficiency of the method was confirmed by recovery tests.     

Flow-Injection Determination of Toxic Aromatic Amines in Medicinal Preparations

Working conditions were found for the flow-injection determination with spectrophotometric detection (510 nm) of the toxic aromatic amines p-aminophenol (I) and o-phenylenediamine (II) as 4,6-dinitrobenzofuroxan derivatives in mixtures on the basis of Paracetamol and Dibazol medicines. The optimal results were obtained with the use of flows of an ethanol (methanol)–buffer solution at pH 6.68. The analytical range of the toxicants is 0.03–0.98 g/mL. The detection limit is 0.025 g/mL for I and 0.01 g/mL for II. Compounds I and IIwere determined in medicinal forms (pellets, syrup, and suppositories) and in reaction mixtures in the synthesis of Paracetamol and Dibazol.     

Simultaneous Spectrophotometric Determination of Paracetamol and P‐Aminophenol by Using Mean Centering of Ratio Kinetic Profiles

A specific spectrophotometric method was developed for simultaneous determination of paracetamol (PCT) and p‐aminophenol (PAP) in water samples without prior separation steps. The method is based on the mean centering of ratio kinetic profiles. Paracetamol and P‐aminophenol react with Fe(III)/hexacyanoferrate(III) complex and result in the formation of colored complex, i.e. Prussian Blue. The differences in the rate of reaction of PCT and PAP with reagents make their simultaneous determination feasible by using mean centering of ratio kinetic profiles. The experimental parameters, such as reagent concentrations and pH were optimized for getting results with minimum errors. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) for the simultaneous determination of binary mixtures of p‐aminophenol and acetaminophen were calculated. The results show that the method was capable of simultaneous determination of 0.5–21.0 μg mL⁻¹ and 0.1–15.0 μg mL⁻¹ of PCT and PAP, respectively. The proposed method was successfully applied to the simultaneous determination of paracetamol and p‐aminophenol in several pharmaceutical products and synthetics mixtures.     

Electrocatalytic Determination of 6‐Tioguanine at a p‐Aminophenol Modified Carbon Paste Electrode

A p‐aminophenol modified carbon paste electrode (p‐APMCPE) was constructed for determination of an anticancer drug 6‐thioguanine (6‐TG). The cyclic voltammogram showed that the electrocatalytic oxidation of 6‐TG at the surface of p‐APMCPE occurs at a potential about 840 mV less positive than at an unmodified electrode. Square‐wave voltammetry results presented that the electrocatalytic oxidation peak currents of 6‐TG in pH 9.0 had two linear dynamic ranges in the range of 0.2 to 8.0 and 8.0 to 350.0 μM 6‐TG with a detection limit of 0.08 μM. The kinetic parameters such as electron transfer coefficient (α) and rate constant were determined for the chemical reaction between 6‐TG and p‐aminophenol. Finally, this method was evaluated for the determination of 6‐TG in 6‐thioguanine tablets and urine samples.     

Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and-acid chloride with various aminophenols

The 1H-pyrazole-3-carboxylic acid 1 was converted via reactions of its acid chloride 2 with various aminophenol derivatives 3a--d into the corresponding N-(hydroxyphenyl)-1H-pyrazole-3-carboxamides 4a--d, respectively, in good yields (34–53%). The reactions of 1 or 2 with 3 in benzene or toluene for 5–7 h with no catalytic amounts of base lead to the formation of the products 4. The structures of all new synthesized compounds were established by the ¹³C NMR,¹H NMR, IR, masss spectroscopic data and elemental analyses. The reaction mechanism of 2 with 3 was studied by means of the RHF/3-21G and RHF/6-31G method.     

NICKEL(II) AND EUROPIUM(III) COMPLEXES OF THE AMINOPHENOL LIGAND: 2-(DIETHYLAMINO)METHYLPHENOL (N∼OH). CRYSTAL STRUCTURES OF THE Ni(N∼O)2 AND [Eu(NO3)3(HN∼O)2]2 COMPLEXES

Abstract

The first Ni(II) compounds with aminophenol ligands were synthesized by reaction of 2-diethylaminomethylphenol and 2-diethylaminomethyl-4-methylphenol (N ～ OH) with dehydrated NiCl₂ in ethanol. They were characterized as tran-square planar Ni(N ～ O)₂ complexes by NMR and IR spectroscopies, mass spectrometry, elemental analysis and X-ray structure determination. When the ligand was reacted with Eu(NO₃)₃, the new dimeric complex [Eu(NO₃)₃(HN ～ O)₂]₂ was isolated. Elemental analysis, IR, magnetic moment and X-ray diffraction indicated that in this case formally neutral aminophenol ligands, in their zwitterionic form, are attached to the metal center through the phenolato oxygen and act either as bridging or as terminal groups. Their protonated amino substituents are involved in strong N—H—O hydrogen bridging. The metal shows nine-coordination, the coordination sphere of each europium being completed by three NO₃ groups.     

4-Acetylpyridine 2-Benzothiazolylhydrazone as a Chromogenic Reagent for Common Epoxides

Abstract

A simple and sensitive color reaction of common epoxides as well as other some alkylating agents with 4-acetylpyrldine 2-benzothiazolylhydrazone (ABH) is described. These compounds gave a purpllsh red color after reaction with ABH for 2 hrs at 110°C in methyl cellosolve or for 20 min at 120°C followed by treatment with plperazlne on silica gel thin-layer plates. Four aliphatic terminal epoxides could be determined spectrophotometrically in the range from 20 to 125 nmol/ml. The limits of detection of these epoxides on silica gel thin-layer plates were 10 pmol/spot order by the visual inspection. The reaction mechanism is also discussed based on the chemical structure of the isolated chromophore.     

Structure of zinc-5,15-di(o-methoxyphenyl)octaalkylporphyrines and their reaction with organic peroxides in the presence of pyridine

By combined spectral and calculation methods the structure of zinc 5,15-di(o-methoxyphenyl)-2,8,12,18 3,7,13,17-octaalkylporphyrinates (I, II) and their properties in the reaction with organic peroxides with addition of different amounts of pyridine were studied. The reaction of zinc porphyrinates with peroxides in the presence of pyridine leads to destruction of the complex chromophore. Kinetic parameters of the investigated reaction (effective k _ef and true k _V rate constants) are obtained. The presence of base in the reaction medium is found to lead to a change in the structure of the zinc porphyrinates and affects the rate of oxidation. By quantum-chemical method PM3 the geometry of the reagents was calculated and the deformation distortions of the reactants molecules and intermediates in the course of the oxidation reaction was demonstrated. The influence of electronic effects of substituents and the degree of deformation of the zinc porphyrinate macrocycle on their redox properties is revealed.     

High-Performance Liquid Chromato- Graphic Assay for Kinetic and Inhibition Properites of Monoamine Oxidase form A

Abstract

A rapid and convinient method to study the kinetic and inhibition properties of rat brain monoamine oxidase form A by high-performance liquid chromatography is described. The procedure consists of homogenization of the brain tissue, enzymatic reaction with or without inhibitors using 5-hydroxytryptamine as the substrate, termination of the reaction with perchloric acid, removal of protein by centrifugation and detection of reaction products at 280 nm after HPLC separation. The method was applied to determine K_m and V_max values of 5-HT for MAO-A and to study the inhibition properties of MAO-A using clorgyline and 1-deprenyl as inhibitors.     

Sensitive Spectrophotometric Determination of Some Dibenzazepine Drugs with Diazotized P-Phenylenediamine Dihydrochloride

ABSTRACT

A simple, sensitive and selective spectrophotometric procedure was developed for the determination of imipramine hydrochloride, desipramine hydrochloride, clomipramine hydrochloride and trimipramine maleate belonging to dibenzazepine class of drugs. The method is based on the interaction of diazotized p-phenylenediamine dihydrochloride with the drug in sulphuric acid medium. The resulting chromophore was measured at 565 nm, and was stable for about 2.5 hr. The commonly encountered excipients and additives do not interfere with the determination. Dibenzazepine drugs can be determined in the range of 0.1-4.0 μg/ml, with a relative standard deviation of 1.92% for ten replicate measurement of 2.0 μg/ml dibenzazepine drugs. Results from the analysis of preformulations and commercial tablets by this procedure agree well with those of the official method.     

Selective Kinetic Spectrophotometric Determination of Nitrite in Food and Water

Abstract

A highly selective and sensitive method for the kinetic spectrophothometric determination of sub-microgram amounts of nitrite has been development based on its reaction with Nile blue 2B in acidic medium. The reaction is monitored spectrophotometrically at 595 nm at a fixed time of 4.5 min. The change in absorbance at 595 nm is related to the concentration of nitrite in the range 0.005 - 1.100 μg.ml^?1 The detection limit is 0.001 μg.ml^?1. The relation standard deviation is 1% for 0.020 μg.ml^?1 of nitrite for ten replicate measurements. Most common anions and cations do not interfere. The procedure was applied to the determination of trace amounts of nitrite in sausage and water.     

Spectrofluorimetric Determination of Gallium with 5-Bromosalicylidene-o-Aminophenol

Abstract

A method for the determination of trace amounts of gallium has been developed, based on the formation of a fluorescent complex between Ga (III) and 5-Bromosalicylidene-o-aminophenol (5-BrSOAPh). With excitation at 425 nm the chelate has an emission maximum at 520 nm. The reaction is carried out at apparent pH (pH?) 5.40 in an aqueous-ethanol medium (60% V/V ethanol). The influence of the reaction variables is discussed.     

Comparison of the optical properties of radiata pine TMP and CTMP pulps and the starting wood

The reflectivity, specific light scattering coefficients and specific light absorption coefficients of earlywood and latewood in each ring from three radiata pine discs were determined at 457 nm. Significant ring-to-ring and within-ring variation was observed. A method was developed to determine the light absorption spectra of the wood. Comparison with that of TMP pulp showed that during refining a chromophore with a maximum absorption at 430 nm was produced. It is suggested that this is the same chromophore as that produced during light-induced yellowing of mechanical pulps, possibly ano-quinone. Chromophore formation was less when sulfite was present.     

Ultraviolet action spectrum (238-405 nm) for inhibition of glycine uptake in E. coli.

Abstract— Initial rate of uptake of ³H-glycine by Escherichia coli B/r was measured immediately after irradiation with monochromatic light. Uptake was proportional to time for at least 2 min in both control and irradiated samples. Inhibition of uptake is an exponential function of fluence to about 20% remaining activity, beyond which it is much more resistant to irradiation, suggesting two different uptake systems. The principal (sensitive) system shows an F₃₇ of 2.2 kJ/m² at 280 nm and 110 kJ/m² at 334 nm. The response is independent of cell killing and of presence of the rel gene. The chromophore remains unidentified, although an action spectrum suggests a protein chromophore in the far-UV (below 300 nm) region and a menaquinone chromophore in the near-ultraviolet (above 300 nm). A 10–20%, stimulation of uptake rate, which we cannot account for, is observed at low fluences (generally below 100 kJ/m²) at 313, 366 and 405 nm, but not at 334 nm.