J.J.Berzas Nevado

Kinetic spectrophotometric determination of nanogram levels of manganese by use of the salicylaldehyde guanylhydrazone-hydrogen peroxide system

A kinetic method is described for determining trace amounts of manganese(II), based on its catalytic effect on the oxidation of salicylaldehyde guanylhydrazone by hydrogen peroxide. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 505 nm. The calibration graph is linear in the range 8-80 mug/l. with a relative error of +/- 1%. The method has been applied to the determination of manganese in various samples.

Determination of Amitraz in Honey by First-Derivative Spectrophotometry

Abstract A new method for the determination of 1,5-bis(2,4-dimethylphenyl)-3-methyl-1,3,5-triazopenta-1,4-diene (Amitraz) in honey by derivative spectrophotometry is proposed. Amitraz is extracted from aqueous honey solutions with CCI4 and it is determined between 0.1 and 1.5 μg. ml−1 from the first-derivative spectrum by measuring the peak amplitude at 332 nm (1D332), as the vertical distance from the peak to the baseline.

Analytical properties of pyridine-2-aldehyde guanylhydrazone

The modified synthesis and analytical properties of pyridine-2-aldehyde guanylhydrazone are described for the first time. The solubility, spectral char.

Extractive-spectrophotometric determination of molybdenum as an ion-association complex with thiocyanate and adogen

A selective and sensitive method is described for the determination of trace amounts of molybdenum, based on its reaction with thiocyanate and its extraction (into toluene) as an ion-association complex formed with adogen (methyltrioctylammonium chloride). The molar absorptivity is 2.13 x 10(4) l.mole(-1).cm(-1) at lambda(max) 467 nm. The method has been applied to molybdenum determination in steels.

Analytical properties of 1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride

The synthesis and analytical properties of 1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride are described for the first time. The solubility, spectral characteristics, pK values and reactions with 40 cations and 13 anions are reported.

Kinetic-spectrophotometric determination of Cu(II) and pyridine by use of the aerial oxidation of dimedone bisguanylhydrazone

The synthesis and analytical properties of dimedone bisguanylhydrazone (DIBG) are described for the first time. DIBG is oxidized by aerial oxygen and the reaction is catalysed by copper(II). The catalytic effect of copper(II) is increased by the presence of pyridine. Kinetic methods are described for determining trace amounts of copper(II) and pyridine. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 550 nm. The calibration graphs are linear in the range 0.6-9.5 mug for copper(II) and 0.2-8.8 mg for pyridine. The methods have been applied to the determination of copper in galena and of pyridine in piperidine and isoamyl alcohol. The kinetic parameters of the reaction have been determined.

Spectrophotometric determination of trace amounts of iron(III) by extraction of the mixed-ligand iron—fluoride—purpurin complex

The characteristics of the mixed-ligand iron(III)-fluoride-purpurin complex, including optimum conditions of formation and extraction into methyl isobutyl ketone are described. A procedure for determination of trace amounts of iron in fluoride medium (0.5M) with purpurin (1,2,4,-trihydroxy-anthraquinone) in methyl isobutyl ketone is given. The method is suitable for determining iron in the presence of large amounts of aluminium, cyanide, phosphate and nickel.

Cyclohexane-1,3-dione bisthiosemicarbazone monohydrochloride as a spectrophotometric reagent for the rapid determination of chlorate in perchloric acid medium

Cyclohexane-1,3-dione bisthiosemicarbazone monohydrochloride produces coloured solutions with chlorate ions in perchloric acid medium, in the presence of chloride ions. The yellow colour obtained (molar absorptivity 1.7 × 104 l mol–1 cm–1 at a wavelength of 402 nm) has been used for the spectrophotometric determination of trace amounts of chlorate. The reaction is of considerable interest, as at present few useful colour reactions are known for the chlorate ion. An important advantage of using this reagent is the stability of the yellow coloured solution obtained.

Simultaneous determination of sulphathiazole and sulphanilamide in pharmaceuticals by derivative spectrophotometry

Third-order and fourth-order derivative spectra have been used for determining sulphathiazole, sulphanilamide and their binary mixtures. The method is suitable for 1-22 micrograms ml-1 of sulphathiazole and for 0.5-14 micrograms ml-1 of sulphanilamide and can be applied for determining the sulphonamides in pharmaceuticals.

Salicylaldehyde guanylhydrazone as an analytical reagent for spectrophotometric estimation of iron

Abstract The properties and analytical possibilities of salicylaldehyde guanylhydrazone as spectrophotometric reagent have been examined. A new method for the determination of iron has been developed. Iron can be determined in the presence of the oxalate, tartrate, citrate, aluminum, and others.