Chelating and free radical scavenging mechanisms of inhibitory action of rutin and quercetin in lipid peroxidation.

When working in the field ofhost–guest chemistry, the binding constants have to bedetermined on many occasions Here is a detaileddocument of how to determine the binding constantswhich covers both the basic principle and thepractical issue: a practical experimental guideline,a representative method for the determination ofstoichiometry and for the evaluation of a complexconcentration, precautions to be taken on setting upconcentration conditions of the titration experiment,practical data-treatment methods and estimation ofstatistical errors This document is described indetail using the basic level of mathematics,statistics, and programs of spreadsheet softwareEspecially, the titration experiments by means ofUV-visible and NMR spectroscopy are carried out anddescribed

A Practical Guide for the Determination of Binding Constants

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Rational Design of Sequestering Agents for Plutonium and Other Actinides

The water-soluble titanium(IV)–porphyrin complex, oxo[5, 10, 15, 20-tetra(4-pyridyl)porphyrinato]titanium(IV)[TiO(tpyH4)4+], was found to enhance the spectrophotometric determination of trace amounts of hydrogen peroxide. A 0.05 mol dm–3 hydrochloric acid solution containing TiO(tpypH4)4+ was used (the Ti—TPyP reagent), the absorbance of which decreased at 432 nm as hydrogen peroxide was added. This was due to the consumption of the TiO(tpypH4)4+ complex following the formation of peroxo[5, 10, 15, 20-tetra(4-pyridyl)porphyrinato]titanium(IV). The decrease in absorbance at 432 nm (ΔA432) was proportional to the concentration of hydrogen peroxide, from 1.0 × 10–8 to 2.8 × 10–6 mol dm–3, in the sample solution (25 pmol–7.0 nmol per assay). The reaction was accelerated by hydrogen ions; the presence of 1.6 mol dm–3 perchloric acid was found to promote complexation to the greatest extent. A ΔA432 of 1.9 × 105 was found for 1 mol dm–3 hydrogen peroxide. A measurement precision of 1.2% for 1.0 × 10–6 mol dm–3 hydrogen peroxide (n= 8) was obtained. The reagent can be used for the determination of hydrogen peroxide in water samples such as tap water and rainwater over the range from 1.05 × 10–7 to 3.34 × 10–5 mol dm–3.

A Letcher. Jones

Papers

Colorimetric Determination of Iron with Disodium-1,2-dihydroxybenzene-3,5-disulfonate