The possibilities of polarography in the chemistry of nitroazoles

1984 ◽  
Vol 49 (6) ◽  
pp. 1342-1353 ◽  
Author(s):  
Dragica Dumanović ◽  
Janka Ćirić ◽  
Djuro Kosanović ◽  
Dragoslav Jeremić
Keyword(s):  
Nitro Group ◽  
Systematic Investigation ◽  
Nitro Compounds ◽  
The Other ◽  
Polarographic Method ◽  
Spectrophotometric Methods ◽  
Group Position ◽  
High Yields

Based on systematic investigation of mononitroimidazoles, selective polarographic and spectrophotometric methods for determination of nitrazole compounds in reaction mixture are proposed. It was proved that the selectivity is based on the different properties of the nitro group due to the effects of the nitro group position in the ring, the type and position of the other substituents and on the fact whether the compound is N-substituted or not. The proposed methods can be successfully used for monitoring the synthetic procedures and decreasing the number of experiments for optimization. Based on the anticipated and proved behaviour of the nitro compounds of pyrazole, novel mononitropyrazole derivatives were synthetized in a new way and with high yields. Applying the polarographic method it was discovered that during N-substitution of tautomeric mononitroimidazole and mononitropyrazole substrates other byproducts were obtained besides the main products and undesired isomers. The products were identified and then a correct and more complete N-substitution scheme could be given. Following quantitatively these N-substitution processes conclusions which directly concern the mechanism of reactions were drawn.

Simple Determination of Ranitidine in Dosage Forms by In-Phase Selective AC Polarography

1988 ◽  
Vol 71 (2) ◽  
pp. 388-390
Author(s):  
Juan A Squella ◽  
Luis A Zuñiga ◽  
Igor Lemus ◽  
Luis J. Nuñez Vergara
Keyword(s):  
Sample Preparation ◽  
Nitro Group ◽  
Dosage Forms ◽  
Polarographic Method ◽  
Precision And Accuracy

Abstract A new AC polarographic method for the determination of pharmaceutical forms of ranitidine is proposed, based on the electroactivity of the ranitidine nitro group. Individual and composite assays as well as recovery studies are described. Results show adequate precision and accuracy. Sample preparation is easy and no excipient separation is required.

scholarly journals Fingerprint Spectrophotometric Methods for the Determination of Co-Formulated Otic Solution of Ciprofloxacin and Fluocinolone Acetonide in Their Challengeable Ratio

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Reem H. Obaydo ◽  
Amir Alhaj Sakur
Keyword(s):  
Single Dose ◽  
Original Method ◽  
Fluocinolone Acetonide ◽  
The Other ◽  
Resolution Method ◽  
Spectrophotometric Methods ◽  
Enrichment Technique ◽  
Sample Enrichment ◽  
Constant Multiplication

Six spectrophotometric methods were developed to determine a new single-dose otic solution known as “Otovel®,” which consists of two components: the major one is ciprofloxacin (CIP) and the minor is fluocinolone acetonide (FLU). The ratio of (CIP) and (FLU) in Otovel® is 12 : 1, which is considered a challengeable ratio for UV determination. Thus, spectrum addition as a sample enrichment technique was required for the analysis of (FLU) low concentration. All these methods were capable of resolving the spectra for each component in D0 belonging to the fingerprint resolution technique. The former absorptivity centering (a-centering) method was recently developed in 2018; it was effectively applied for its solution of both binary components in Otovel®, while another method, ratio subtraction (RS), is considered as an original resolution method that could be applied to determine only one component in mixtures. However, the other four methods that are related to their original method (RS) were extended ratio subtraction (EXRS), constant multiplication (CM), unified constant subtraction (UCS), and spectrum subtraction (SS). They were also easily applied for completing the quantification of binary mixture drugs present in Otovel®. The linearity ranges were found to be 3.0–15.0 μg/mL for (CIP) and (FLU), respectively. All results acquired from the proposed methods were successfully estimated according to ICH criteria and were statistically compared with official ones where no differences were noticed.

scholarly journals Application of Inorganic Oxidants to the Spectrophotometric Determination of Ribavirin in Bulk and Capsules

2006 ◽  
Vol 89 (2) ◽  
pp. 341-351 ◽  
Author(s):  
Ibrahim A Darwish ◽  
Alaa S Khedr ◽  
Hassan F Askal ◽  
Ramadan M Mohamed
Keyword(s):  
Ammonium Sulfate ◽  
Acid Medium ◽  
Chromium Trioxide ◽  
Potassium Dichromate ◽  
Ammonium Molybdate ◽  
The Other ◽  
Potassium Iodate ◽  
Potassium Periodate ◽  
Spectrophotometric Methods

Abstract Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.99840.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 41400 g/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2101.2 0.481.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia.

The Nitration of α- and β-Acylnaphthalenes

1995 ◽  
Vol 48 (12) ◽  
pp. 1969 ◽  
Author(s):  
SD Barker ◽  
K Wilson ◽  
RK Norris
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Acetic Anhydride ◽  
Nitro Compound ◽  
Nitro Compounds ◽  
The Other ◽  
Coupling Constant ◽  
Significant Extent ◽  
Nitro Derivatives ◽  
High Yields

The nitration of α- and β- acylnaphthalenes with copper(II) nitrate in acetic anhydride or nitric acid/acetic acid mixtures gives high yields of the corresponding mononitro compounds. The assignment of constitution to these products is made on the basis of extensive 1H n.m.r. chemicl shift and coupling constant data. In the case of α- acylnaphthalenes, with the notable exception of α- pivalonaphthone, nitration occurs in the α-positions of the unsubstituted ring to give mixtures of 5- and 8-nitro compounds. α- Pivalonaphthone gives appreciable amounts of the 4-nitro compound and also of the 8-nitro compound. This result indicates that the pivaloyl group does not shield the 8-position sterically to any significant extent and is effectively electronically neutral, unlike the other acyl substituents , in allowing attack at the α-position (position 4) of the acylated ring. This result is ascribable to the lack of coplanarity of the pivaloyl group with the naphthalene system. All of the β- acylnaphthalenes gave mixtures of 4-, 5- and 8-nitro derivatives in proportions that did not vary significantly with the nature of the acyl group.

scholarly journals Spectrophotometric determination of niclosamide Via Schiff ’s base formulations in pharmaceutical and veterinary preparations

2019 ◽  
Vol 7 (1) ◽  
pp. 1-9
Author(s):  
Othman N S ◽  
Saleem I T
Keyword(s):  
Nitro Group ◽  
Acidic Medium ◽  
Zinc Powder ◽  
Apicomplexan Parasite ◽  
Spectrophotometric Methods ◽  
Optimum Ph ◽  
Colored Product ◽  
Blank Solution

Introduction: Niclosamide(NICS) its chemical name 5-chloro-N-(2- chloro-4-nitrophenyl)-2-hydroxybenz-amide]is the only commercially existing molluscicide optional by the WHO for large extent use in schistosomiasis be in charge of programs . NICS and its two new synthesized derivatives constructed to float on the water surface were able to kill cercariae, also obsessed promising activity in vitro nearby to an apicomplexan parasite Toxoplasma (4). Few spectrophotometric methods have been reported for the estimation of NICS as pure and in formulations, approximately these methods depend on reduction of nitro group (almost with zinc powder in acidic medium) followed by reaction with different reagents. The method based on reduction of nitro group of NICS then  reaction of reduced-NICS with para- N,N dimethylaminobenzaldehyde in non-aqueous medium (methanol) to form a colored product that has been proved successfully for the estimation of NICS in pharmaceutical and veterinary formulations Material and method :All reagents used are of analytical grade and are obtained from Fluka or Aldrich , NICS wassupplied from SIGMA companies. Methanolic solution of para- N,N- dimethylanimobenzaldehyde (Fluka)3%, weighing 3 g and dissolved in 100 ml methanol in a volumetric flask. All other reagents were prepared bydissolving the propriety weight in perfect solvent. A volume in the range of 0.1 to 1.7 ml of 100 µg.ml-1RNICS solution was transferred to 10 ml calibrated flasks.2ml of PNNDMABA (3.0 %) was added, and the volume was made up to 10 ml by adding methanol. The yellow Schiff ’s base was measured at 454 nm versus a blank solution. Results and Discussion:The optimum pH for reaction of NICS with para-N, N-dimethylanimobenzaldehyde equal to 3 which resulted by mixing the components of the reaction. The absorbance increase with increasing reagent concentration (para-N,N- dimethylanimobenzaldehyde) and reached maximum on adding volume of 2.0 ml of (3%), which also gives the highest value of determination coefficient (R2).The experimental data indicated that methanol was the optimum solvent used in dilution according to high intensity of Schiff ’s base and the good stability. The formation of the yellow Schiff ’s base being complete after mixing the components of reaction and the absorbance remained constant for at least 2 hours. Conclusion: Accurate and sensitive spectrophotometric method was described for the estimation of NICS. The present method has been successfully applied for the estimation of NICS in pharmaceutical and veterinary preparations.

scholarly journals New spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations.

2005 ◽  
Vol 52 (4) ◽  
pp. 915-922 ◽  
Author(s):  
Nafisur Rahman ◽  
Syed Najmul Hejaz Azmi
Keyword(s):  
Nitro Group ◽  
Potassium Hydroxide ◽  
Pharmaceutical Formulations ◽  
Ammonium Molybdate ◽  
Dimethyl Sulphoxide ◽  
Hypothesis Tests ◽  
Molybdenum Blue ◽  
Spectrophotometric Methods ◽  
Beer’S Law

Two simple, sensitive and economical spectrophotometric methods were developed for the determination of nifedipine in pharmaceutical formulations. Method A is based on the reaction of the nitro group of the drug with potassium hydroxide in dimethyl sulphoxide (DMSO) medium to form a coloured product, which absorbs maximally at 430 nm. Method B uses oxidation of the drug with ammonium molybdate and subsequently reduced molybdenum blue is measured at 830 nm. Beer's law is obeyed in the concentration range of 5.0-50.0 and 2.5-45.0 microg ml(-1) with methods A and B, respectively. Both methods have been successfully applied for the assay of the drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. The reliability and the performance of the proposed methods are established by point and interval hypothesis tests and through recovery studies.

Determination of the lattice translation across {110} APBs in GaAs

1988 ◽  
Vol 46 ◽  
pp. 600-601
Author(s):  
D.R. Rasmussen ◽  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Lower Energy ◽  
Antiphase Boundary ◽  
The Other ◽  
Boundary Structure ◽  
Interface Plane ◽  
Inversion Symmetry ◽  
High Angle ◽  
Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 330-331
Author(s):  
Y. Ishida ◽  
H. Ishida ◽  
K. Kohra ◽  
H. Ichinose
Keyword(s):  
High Order ◽  
Simulation Technique ◽  
The Other ◽  
Image Simulation ◽  
Diffraction Vector ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image ◽  
Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

Procedures for the Quantitative Determination of Autoprothrombin C

1962 ◽  
Vol 08 (03) ◽  
pp. 434-441 ◽  
Author(s):  
Edmond R Cole ◽  
Ewa Marciniak ◽  
Walter H Seegers
Keyword(s):  
Quantitative Determination ◽  
Plasma Sample ◽  
Quantitative Measure ◽  
The Other ◽  
Clotting Time ◽  
Bovine Plasma ◽  
Autoprothrombin C

SummaryTwo quantitative procedures for autoprothrombin C are described. In one of these purified prothrombin is used as a substrate, and the activity of autoprothrombin C can be measured even if thrombin is in the preparation. In this procedure a reaction mixture is used wherein the thrombin titer which develops in 20 minutes is proportional to the autoprothrombin C in the reaction mixture. A unit is defined as the amount which will generate 70 units of thrombin in the standardized reaction mixture. In the other method thrombin interferes with the result, because a standard bovine plasma sample is recalcified and the clotting time is noted. Autoprothrombin C shortens the clotting time, and the extent of this is a quantitative measure of autoprothrombin C activity.

Sign in / Sign up

Export Citation Format

Share Document