Shozo Shibata

Solvent extraction and spectrophotometric d.etermination of metals with 1 -(2-pyridylazo)-2-naphthol

Abstract PAN(1-(2-pyridylazo)-2-naphthol) is proposed for the solvent extraction and spectrophotometric determination of manganese, iron, cadmium, mercury, gallium, and yttrium. The reagent, which is highly specific for iron, has been applied to the determination of iron in clay and anorthosite. The separation of yttrium from lanthanum and the separation of manganese from nickel were successful.

Solvent extraction behavior of some metal-1-(2-pyridylazo)-2-naphthol chelates

Summary The compound 1-(2-pyridylazo)-2-naphthol (PAN) has been found to be a sensitive and selective colorimetric reagent for manganese (II), indium, gallium, cadmium, zinc, nickel, mercury, and iron(III) if the pH is suitably controlled.

Dual-wavelength spectrophotometry: Part VI. Qualitative and quantitative analysis by means of first-derivative spectra

Abstract Derivative spectrophotometry has many important applications, e.g. detecting trace chemicals in mixture and analyzing isomers or turbid samples, but such measurements have been difficult instrumentally. The first-derivative spectrum can be recorded easily by using dual-wavelength measurements, if the two wavelengths λ 3 and λ 2 are set very close to each other (usually 1–2 nm apart) and scanned simultaneously. Practical applications of derivative spectra in the analysis of rare earths and phenol mixtures are described.

4-[(5-chloro-2-pyridyl)AZO]-1,3-diaminobenzene as a new sensitive and selective reagent for cobalt

Abstract Cobalt (II) and 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) in slightly acid, neutral or alkaline medium form a pink-coloured complex. This complex is very stable even in the presence of strong mineral acid. The complex has two absorption maxima at 530 and 570 nm in hydrochloric acid (2.4 M ) solution. The colour is very stable and the system conforms to Beers law; the optimal range for measurements in a 1 -cm cell is 0.02–0.5 p.p.m. cobalt. Common anions and cations do not interfere; only chromium (VI) interferes seriously. The molar absorptivity is 1.13·10 5 1 mol −1 cm −1 at 570 nm. The sensitivity is 0.00051 μg Co cm −2 at 570 nm for log I 0 / I = 0.001.

Dual-wavelength spectrophotometry: General method

Abstract The application of dual-wavelength spectrophotometry in inorganic chemical analysis is discussed. The method has been successfully applied to the determination of trace amounts of metals and the determination of metals in the presence of diverse ions without separation. Three basic methods for the choice of the two wavelengths to be used for a particular system are proposed.

SPECTROPHOTOMETRIC DETERMINATION OF RARE EARTH METALS WITH 1-(2-PYRIDYLAZO)- 2-NAPHTHOL

Abstract 1-(2-Pyridylazo)-2-naphthol (PAN) reacts very sensitively with rare earth metals to form a deep red precipitate in alkaline solution; this can be extracted with ether, except in the case of lanthanum, cerium and scandium. Absorption maxima occur at 530 and 560 mμ. Traces of rare earth metals may be determined in the presence of many foreign metals.

Dual-wavelength spectrophotometry: The determination of mixtures

Abstract A simple rapid spectrophotometric method for the determination of two-component systems by means of a dual-wavelength method is described. By proper selection of the combination of two wavelengths λ1 and λ2, one component can be masked instrumentally even when its concentration varies. The component to be determined is measured as follows: two light beams of different wavelengths λ1 and λ2, from two gratings are time-shared through a single cell by means of a rotating sector and the difference between the absorbance at wavelengths λ1 and λ2, is measured. Analysis of mixtures of o- and p-nitrophenol, and of iso- and terephthalic acid, is discussed.

Syntheses of azo dyes containing 4,5-diphenylimidazole and their evaluation as analytical reagents

Abstract Eight azo dyes containing the 4,5-diphenylimidazole group have been synthesized, and their potential for determinations of metals has been studied spectrophotometrically. Of these reagents, the pyridylazo and quinolylazo derivatives are suitable as chromogenic reagents, the best being 2-(quinolylazo)-4,5-diphenylimidazole (QAI), which reacts with several metal ions. The copper and mercury complexes of QAI show molar absorptivities of the order of 80 000 l mol−1 cm−1.

Dual-wavelength spectrophotometry: Part III. Determination of arsenazo I in arsenazo III

Abstract A simple rapid spectrophotometric method for the determination of arsenazo I in the presence of large amounts or arsenazo III by means or a dual-wavelength method is discussed. By proper selection of the combination of two wavelengths, γ1 = 502.0 nm and γ2 = 575.3 nm, arsenazo III can be masked instrumentally even when its concentration varies. By this method about 0.5– 40%of arsenazo I in arscnazo III can be determined very easily and accurately.

2-[2-(5-Bromopyridyl)azo]-5-dimethylaminophenol; a new sensitive reagent for cadmium

Abstract Cadmium(II) reacts with 2-[2-(5-bromopyridyl)azo]-5-dimethyl-aminophenol (5-Br-DMPAP) in aqueous solution; the complex can be extracted with organic solvents such as chloroform, 3-methyl-l-butanol and methyl isobutyl ketone at pH 8–10.5 to give a red solution which absorbs at 525–555 nm. The absorbance in organic solvents is stable and the system conforms to Beers law; the optimal range in 3-methyl-1-butanol for measurement in 1.00-cm cells is 0.01–l p.p.m. cadmium. Moderate amounts of many cations and anions do not interfere, and interfering cations such as zinc, copper, manganese and nickel can be separated by extraction with dithizone. The 5-Br-DMPAP method is one of the most sensitive procedures available for the determination of cadmium; the molar absorptivity in a 3-methyl-1-butanol extract is 1.41·10 5 1 mol −1 cm −1 at 555 nm.