Spectrophotometric Determination of Lisinopril Drug by Oxidative Coupling Reaction with 4-aminonaphthalene-1- sulfonic acid Reagent

Spectrophotometric Determination of Catecholamines based on their Oxidation Reaction Followed by Coupling with 4-Aminobenzoic Acid

Um método espectrofotométrico simples e sensível para a determinação de dopamina, metildopa, levodopa e catecol, puros, em formulações farmacêuticas, e em água, é descrito. O método é baseado na reação de oxidação com periodato, seguida pelo acoplamento oxidativo com ácido 4-aminobenzóico em pH 4, levando à formação de produtos coloridos. O gráfico de calibração foi linear no intervalo de 0,20-...

Catalytic spectrophotometric determination of vanadium in seawaters based on the bromate oxidative coupling reaction of metol and 2,3,4-trihydroxybenzoic acid.

A new, simple, sensitive and selective catalytic method is developed for the determination of vanadium in natural and sea waters. The method is based on the catalytic effect of V(V) and/or V(IV) on the bromate oxidative-coupling reaction of metol with 2,3,4-trihydroxybenzoic acid (THBA). The reaction is followed spectrophotometrically by tracing the oxidation product at 380 and/or 570 nm after ...

Preconcentration of Trace Vanadium with the Ion Pair of 2-Nitroso-1-Naphthol-4-Sulfonic Acid and Tetradecyldimethylbenzylammonium Chloride Onto Microcrystaline Naphthalene and Determination by Derivative Spectrophotometry

Vanadium is quantitatively retained on 2-nitroso-1-naphhthol-4-sulfonic acid tetradecyldimethlbenzyammonium chloride onto microcrystalline naphthalene in the pH range of 3.0-4.0 from a large volume of aqueous solutions of various alloys and synthetic samples. After filtration, the solid mass consisting of the vanadium complex and naphthalene was dissolved with 5.0 mL of dimethylformamide an...

Spectrophotometric determination of ajmaline and brucine by Folin Ciocalteu’s reagent

A rapid and simple spectrophotometric procedure is described for the determination of ajmaline and brucine. The method is based on the development of blue coloured product due to reduction of tungstate and/or molybdate in Folin Ciocalteu’s reagent (FCR) by ajmaline and brucine in alkaline medium. The colour is stable for more than 48 h. The chromogenic reaction has max at 540 nm with molar abso...

Phenylbiguanide-p-Sulfonic Acid as an Analytical Reagent for the Colorimetric Determination of Nickel