Yadvendra K. Agrawal

Correction factors for the glass electrode in aqueous dioxan

The conversion factors for obtaining the hydrogen ion concentration from pH measurements at different mole fractions of dioxan in water at 25, 30 and 35 degrees are reported.

Spectrophotometric Determination of Nitrofurazone

Abstract A new sensitive and seleactive method for rapid and accurated determination of nitrofarazone is described. The nitrofurazone is reacted with hydroxyl-amine hydrochloride in alkaline medium to give hydroxamic acid which forms the purple violet coloured complex with iron (III), FeCl3, in acidic medium. The nitrofurazone was determined in presence of commonly used drugs and additives. The results obtained by the proposed and B.P. methods were compared.

Extraction, Spectrophotometric, and Atomic Absorption Spectrophotometric Determination of Selenium With N-Phenylbenzohydroxamic Acid

Abstract Solvent extraction spectrophotometric and atomic absorption spectrophotometric methods for the determination of selenium(IV) in microgram quantities are described. The selenium(IV) forms yellow colored complex with N-phenylbenzohydroxamic acid (PBHA) extractable into chloroform from 7 M HClO4. Se-PBHA complex has maximum absorbance at 345 nm with a molar absorptivity 1.5 × 105 1 mol−1 cm−1 and Sandells sensitivity 0.000526 μg /cm2. Effect of molarity, reagent concentration, diverse ions on the extraction of selenium complex were studied. The selenium is determined in presence of tellurium.

Separation and microdetermination of rare earth metals with N-phenylbenzohydroxamic acid and xylenol orange

A simple, sensitive and selective method for solvent extraction and spectrophotometric determination of lanthanum(III), praseodymium(III), neodymium(III) and samarium(III) is described. The rare earth metals are extractable into chloroform solution of N-phenylbenzohydroxamic acid (PBHA) at pH9–10. Various parameters are studied to optimize the extraction conditions. Stoichiometry of the complexes and the effect of various ions is discussed. The molar absorptivity is found to increase from 65,000 to 93,000 1·mol−1· cm−1 with the increase in atomic number of the rare earths. The stability constants of the complexes, separation factors and pH5 0 are discussed.

Extraction and spectrophotometric determination of uranium(VI)

A selective method for the solvent extraction and spectrophotometric determination of uranium(VI) is described. Uranium can be extracted into chloroform at pH 6.0 with N-m-chlorophenyl-2-theno-hydroxamic acid (N-m-CPTHA) and determined by spectrophotometry using 1-(2-pyridylazo)-2-naphthol (PAN). The molar absorptivity is 1.50·104 1·mol−1·cm−1 at 560 nm. The system obeys Beers law within the range 0.95–20.00 ppm of uranium. Alternatively, a back-extraction procedure was also developed in which uranium is back-extracted by nitric acid and estimated spectrophotometrically using Arsenazo III. The molar absorptivity is 2.0·104 1·mol−1·cm−1 at 665 nm. The parameters concerning the optimum conditions for the analytical method are discussed. The proposed method is applied precisely for the determination of uranium in rock and sea water samples.

Extraction and spectrophotometric determination of bismuth(III) with N-m-tolyl-p-chlorobenzohydroxamic acid and xylenol orange

A solvent extraction and spectrophotometric method for the determination of microgram amounts of bismuth(III) is described. The bismuth(III) is extracted at pH 4.5 with N-m-tolyl-p-chlorobenzohydroxamic acid and forms a mixed complex with xylenol orange, which gives a red colour, λmax. 530 nm and molar absorptivity 2.0 × 104 l mol–1 cm–1. Bismuth has been determined in alloy and pharmaceutical samples.

Dissociation and complexation ofN-m-tolyl-p-methoxybenzohydroxamic acid with manganese(II), nickel(II), copper(II) and zinc(II)

SummaryThe thermodynamic ionisation and formation constant at different ionic strengths of some divalent metal ions ofN-m-tolyl-p-methoxybenzohydroxamic acid at 25 and 35° were determined in several dioxan∶water media. The solid complexes of CuII, NiII and MnII withN-m-tolylbenzo-,N-m-tolyl-p-methylbenzo- andN-m-tolyl-p-methoxybenzohydroxamic acids were prepared and their magnetic susceptibilities measured at room temperature.

Ion-exchange separation and spectrophotometric determination of vanadium in environmental samples

A selective and sensitive method for the extraction and spectrophotometric determination of vanadium(V) in microgram quantities is described. The molar absorptivity of the yellow vanadium(V)-caffeic acid-Aliquat 336 extract is 1.3 x 10(4) 1.mole(-1).cm(-1) at 370nm. The method is compared with the atomic-absorption spectrometric method and applied to the trace determination of vanadium in steel, alloys, a rock and environmental samples.

Extraction and micro-determination of manganese(II) with oxine and aliquat 336

A sensitive and selective method has been developed for the micro-determination of Mn(II) by the selective extraction of the yellow Mn(II)-8-hydroxyquinolinate complex with a liquid ion-exchanger, Aliquat 336, from basic medium. The molar absorptivity of the complex is 2.2 x 10(4)1.mole(-1).cm(-1) at 420 nm and the colour system obeys Beers law in the range 0.1-3.5 ppm Mn(II) in the final solution. The composition and stability of the complex are discussed. Potential interferents have been examined and the method is applied to analysis of standard steel and bronze samples.

Spectrophotometer Determination of Nitrite Using Salbutamol sulphate as a Reagent

Abstract A simple spectrophotometric method for the trace determination of nitrite (NO− 2) is described. Nitrite is reacted with Salbutamal sulphate in acidic medium which gives a yellow colour in alkaline medium (⩾pH 7) and can be determined in the presence of several cations and anions. Beers law is obeyed in the range of 1.8 to 27.6 ppm of nitrite with the molar absorptivity 1.8 × 103 1 × mole−1 × cm−1 at 4l0 nm. The proposed method can also be utilized for the determination of nitrate (NO− 3) after its reduction to nitrite. The method has been applied for the determination of various samples containing traces of nitrite.