Disubstituted hydroxamic acids and the determination of vanadium

1968 ◽  
Vol 46 (2) ◽  
pp. 327-330 ◽  
Author(s):  
R. M. Cassidy ◽  
D. E. Ryan
Keyword(s):  
Extinction Coefficient ◽  
Metal Chelate ◽  
Visible Region ◽  
Hydroxamic Acids ◽  
Molecular Extinction Coefficient ◽  
Sensitivity Increase ◽  
Chelate Rings

A number of disubstituted hydroxamic acids were investigated as possible replacements for benzoylphenylhydroxylamine in the determination of vanadium; none is superior. At 378 mμ., p-phenylazobenzoylphenylhydroxylamine shows a marked sensitivity increase but selectivity is poor. In the visible region, there is an increase in molecular extinction coefficient as the reagent π system is extended; how ever, complete coplanarity of the aromatic and metal chelate rings is not possible and the increase is not large enough to be of much practical value.

XXXVI.—The Absorption of Light by Inorganic Salts. No. I.: Aqueous Solutions of Cobalt Salts in the Infra-Red

1912 ◽  
Vol 31 ◽  
pp. 521-529 ◽  
Author(s):  
R. A. Houstoun
Keyword(s):  
Aqueous Solutions ◽  
Present Article ◽  
Extinction Coefficient ◽  
Accurate Determination ◽  
Visible Spectrum ◽  
Inorganic Salts ◽  
Absorption Of Light ◽  
Infra Red ◽  
Molecular Extinction Coefficient

The present article is intended to be the first of a series on the absorption of light by solutions of inorganic salts of different elements. With a few scattered exceptions all the work hitherto done on the absorption spectra of inorganic salts has been merely qualitative and has been confined to the visible spectrum. Kayser in his Spectroscopie, vol. iii. p. 45, states that in this field there is work for years and for numerous observers. E. C. C. Baly states in his Spectroscopy, p. 407, that not much is known about the absorption of light in inorganic salts. Merely for its own sake, then, an accurate determination of the molecular extinction coefficient for as many salts under as many different conditions of temperature and concentration, and for as many wave-lengths as possible, would be very valuable.

scholarly journals Development of new spectrophotometric method for estimation of tenofovir disoproxil fumarate using MBTH reagent

2015 ◽  
Vol 4 (4) ◽  
pp. 378-381 ◽  
Author(s):  
Mannem Sri Varsha ◽  
N. Raghavendra Babu ◽  
Yenumula Padmavathi ◽  
P. Ravi Kumar
Keyword(s):  
Tenofovir Disoproxil Fumarate ◽  
Visible Region ◽  
Pharmaceutical Formulations ◽  
Pharmaceutical Journal ◽  
Specific Procedure ◽  
Analytical Validation ◽  
Pharmaceutical Dosage Forms ◽  
Secondary Amine Group ◽  
Validation Procedure

A new simple, sensitive and specific procedure has been developed for determination of tenofovir disoproxil fumarate in bulk and pharmaceutical dosage forms using MBTH reagent. The purpose of this analytical validation procedure is to validate it by laboratory experiments to prove that the method meets the minimum standards for laboratory use. 3-methyl-2-bezothiazoline hydrazone reacts with the secondary amine group of tenofovir in the presence of oxidizing agent, ferric chloride. The resulting apple green coloured chromogen when measured spectrophotometrically in visible region (i.e., 400-800nm) shows a maximum absorbance at 626.5nm. This method can be successfully applied for the determination of drug content in pharmaceutical formulations. The results of analysis have been validated statistically.DOI: http://dx.doi.org/10.3329/icpj.v4i4.22620 International Current Pharmaceutical Journal, March 2015, 4(4): 378-381 

scholarly journals A spectrophotometric method for determination of fluorophore-to-protein ratios in conjugates of the blue fluorophore 7-amino-4-methylcoumarin-3-acetic acid (AMCA)

1990 ◽  
Vol 38 (1) ◽  
pp. 87-94 ◽  
Author(s):  
M W Wessendorf ◽  
S J Tallaksen-Greene ◽  
R M Wohlhueter
Keyword(s):  
Acetic Acid ◽  
Optical Density ◽  
Extinction Coefficient ◽  
Spectrophotometric Method ◽  
Extinction Coefficients ◽  
Beer's Law ◽  
Beer’S Law ◽  
The Given

7-Amino-4-methylcoumarin-3-acetic acid (AMCA) has been found to be a useful fluorophore for immunofluorescence. The present study describes a spectrophotometric method for determining the ratio of moles AMCA to moles protein (or the f/p ratio) in an AMCA-conjugated IgG. The concentration of a substance absorbing light can be determined spectrophotometrically using Beer's Law: Absorbance = Concentration x Extinction coefficient. From Beer's law, one can derive the following formula for determining the f/p ratio of AMCA-IgG conjugates: f/p = (epsilon 280IgG).A350 - (epsilon 350IgG).A280/(epsilon 350AMCA).A280 - (epsilon 280AMCA).A350 where A is the optical density of the conjugate at the given wavelength and epsilon is the extinction coefficient of a substance at the wavelength specified. Using conjugates of model proteins, it was found that the extinction coefficients of the AMCA moiety of AMCA-conjugated protein were 1.90 x 10(4) at 350 nm and 8.29 x 10(3) at 280 nm. Similarly, it was found that the extinction coefficients of swine IgG were 1.56 x 10(3) at 350 nm and 1.26 x 10(5) at 280 nm. Thus, for AMCA-conjugated swine IgG: f/p = (1.26 x 10(5)).A350 - (1.56 x 10(3)).A280/(1.47 x 10(4)).A280 - (6.42 x 10(3)).A350 [corrected]. Based on this formula, the f/p ratios of some AMCA-IgG conjugates useful for immunohistochemistry have been found to range between 6 and 24.

scholarly journals Experimental Determination of the Absorption Cross-Section and Molar Extinction Coefficient of Colloidal CdSe Nanoplatelets

2015 ◽  
Vol 119 (47) ◽  
pp. 26768-26775 ◽  
Author(s):  
Aydan Yeltik ◽  
Savas Delikanli ◽  
Murat Olutas ◽  
Yusuf Kelestemur ◽  
Burak Guzelturk ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Cross Section ◽  
Extinction Coefficient ◽  
Absorption Cross Section ◽  
Molar Extinction Coefficient ◽  
Absorption Cross

Determination of all Dimensions of CdSe Seeded CdS Nanorods Solely via their UV/Vis Spectra

2017 ◽  
Vol 231 (1) ◽  
Author(s):  
Patrick Adel ◽  
Julian Bloh ◽  
Dominik Hinrichs ◽  
Torben Kodanek ◽  
Dirk Dorfs
Keyword(s):  
Absorption Spectra ◽  
Extinction Coefficient ◽  
Core Diameter ◽  
The Core ◽  
Extinction Spectra ◽  
Cds Nanorods ◽  
Fast Route ◽  
Characteristic Points ◽  
Electron Microscopical

AbstractIn the present manuscript we develop a method to determine all characteristic dimensions of CdSe seeded CdS nanorods solely via their extinction spectra without the need for electron microscopical investigations. In detail, the core diameter as well as the overall diameter and length and the molar extinction coefficient can all be derived from characteristic points in the absorption spectra. We carefully investigate in which size regime our assumptions are valid and give an estimation of the expected error, making it possible for the reader to decide whether this method is sufficiently accurate for their respective system. Our method displays a comfortable and fast route to analyze these nowadays often used nanorods.

Conformational analysis of EDTA-type chromium(III) complexes with β-propionato metal chelate rings

2002 ◽  
Vol 609 (1-3) ◽  
pp. 1-9 ◽  
Author(s):  
Sonja Grubišić ◽  
Maja Gruden ◽  
S.R. Niketić ◽  
Narumi Sakagami- Yoshida ◽  
Sumio Kaizaki
Keyword(s):  
Conformational Analysis ◽  
Metal Chelate ◽  
Chelate Rings

Terminology, relative photonic efficiencies and quantum yields in heterogeneous photocatalysis. Part II: Experimental determination of quantum yields

1999 ◽  
Vol 71 (2) ◽  
pp. 321-335 ◽  
Author(s):  
Angela Salinaro ◽  
Alexei V. Emeline ◽  
Jincai Zhao ◽  
Hisao Hidaka ◽  
Vladimir K. Ryabchuk ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Visible Region ◽  
Heterogeneous Photocatalysis ◽  
Quantum Yields ◽  
Yield Data ◽  
Normal Absorption ◽  
The One ◽  
Solid Liquid ◽  
Photonic Efficiency

In the preceding article [Serpone and Salinaro, Pure Appl. Chem., 71(2), 303-320 (1999)] we examined two principal features of heterogeneous photocatalysis that demanded scrutiny: (i) description of photocatalysis and (ii) description of process efficiencies. For the latter we proposed a protocol relative photonic efficiency which could subsequently be converted to quantum yields. A difficulty in expressing a quantum yield in heterogeneous photochemistry is the very nature of the system, either solid/liquid or solid/gas, which places severe restrictions on measurement of the photon flow absorbed by the light harvesting component, herein the photocatalyst TiO2, owing to non-negligible scattering by the particulates. It was imperative therefore to examine the extent of this problem. Extinction and absorption spectra of TiO2 dispersions were determined at low titania loadings by normal absorption spectroscopy and by an integrated sphere method, respectively, to assess the extent of light scattering. The method is compared to the one reported by Grela et al. [J. Phys. Chem., 100, 16940 (1996)] who used a polynomial extrapolation of the light scattered in the visible region into the UV region where TiO2 absorbs significantly. This extrapolation underestimates the scattering component present in the extinction spectra, and will no doubt affect the accuracy of the quantum yield data. Further, we report additional details in assessing limiting photonic efficiencies and quantum yields in heterogeneous photocatalysis.

scholarly journals NEW, GREEN AND MINIATURIZED ANALYTICAL METHOD FOR DETERMINATION OF CEFADROXIL MONOHYDRATE IN CAPSULES

2019 ◽  
Vol 3 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Bianca Marco ◽  
Ana Kogawa ◽  
Hérida Salgado
Keyword(s):  
Analytical Chemistry ◽  
Standard Sample ◽  
Low Cost ◽  
Visible Region ◽  
Hplc Method ◽  
Minimal Amount ◽  
Green Analytical Chemistry ◽  
Color Reagent ◽  
Routine Quality Control

Cefadroxil, an oral antimicrobial, presents few techniques optimized for the reduction of solvents and toxic residues and/or non-use of them. So, a quantitative, new and miniaturized method for determination of cefadroxil monohydrate in capsules has been developed and validated by spectrophotometric method in the visible region according to the international guidelines. The analyzes were performed using microplates containing 96 wells, 1 % of phenolphthalein and sodium hydroxide 0.1 M as reagent at 552 nm. The method was (i) linear in the range of 15-115 µg mL-1, (ii) selective when comparing standard, sample, adjuvants and color reagent, (iii) precise with deviations below 4 %, (iv) accurate when comparing the proposed method with the HPLC method, (v) robusts by making small and deliberate modifications to the method, (vi) besides being fast, low cost, eco-friendly and generates minimal amount of waste. The method can be applied to the routine quality control of cefadroxil monohydrate in capsules and an effective and accessible alternative that contemplates the concepts of current and sustainable green analytical chemistry.

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