Yuroku Yamamoto

Selective determination of arsenic (III, V), antimony (III, V), selenium (IV, VI) and tellurium (IV, VI) by extraction and graphite furnace atomic absorption spectrometry

Abstract Parameters were investigated for the selective determination of arsenic (III, V), antimony (III, V), selenium (IV, VI) and tellurium (IV, VI) by graphite furnace atomic absorption spectrometry combined with extraction using an ammonium pyrrolidinedithiocarbamate and chloroform + carbon tetrachloride solvent mixture. Selenium (VI) and tellurium (VI) were not extracted over the entire range of pH studied, although the extraction conditions for the other species were not critical. It was found that the incorporation of titanium (III) chloride as a reducing agent in the extraction procedure made it possible to differentiate the above elements in the higher and lower oxidation states. The four elements at the low oxidation state were first extracted at pH 5 and after the addition of titanium chloride to the aqueous phase, the species in the high oxidation state were extracted at about pH 0.3. High sensitivity for the determination of the eight species was obtained. Interferences by many foreign ions have been studied.

Differential determination of arsenic(III) and arsenic(V), and antimony(III) and antimony(V) by hydride generation-atomic absorption spectrophotometry, and its application to the determination of these species in sea water

Abstract A method is described for the differential determination of As(III) and As(V). and Sb(III) and Sb(V) by hydride generation-atomic absorption spectrophotometry with hydrogen-nitrogen flame using sodium borohydride solution as a reductant. For the determination of As(III) and Sb(III), most of the elements, other than Ag+, Cu2+, Sn2+, Se4+ and Te4+, do not interfere in an at least 30,000 fold excess with respect to As(III) or Sb(III). This method was applied to the determination of these species in sea water and it was found that a sample size of only 100 ml is enough to determine them with a precision of 1.5–2.5%. Analytical results for surface sea water of Hiroshima Bay were 0.72 μgl−1, 0.27 μgl−1 and 0.22 μgl−1 for As(total), As(III) and Sb(total), respectively, but Sb(III) was not detected in the present sample. The effect of acidification on storage was also examined.

Differential determination of selenium(IV) and selenium(VI) with sodium diethyldithiocarbamate, ammonium pyrrolidinedithiocarbamate and dithizone by atomic-absorption spectrophotometry with a carbon-tube atomizer

The extraction behaviour of selenium(IV) and selenium(VI) with sodium diethyldithiocarbamate, ammonium pyrrolidinedithiocarbamate and dithizone in organic solvents has been investigated by means of flameless atomic-absorption spectrophotometry with a carbon-tube atomizer. The selective extraction of selenium(IV) and differential determination of selenium(IV) and selenium(VI) have been developed. With sodium diethyldithiocarbamate and carbon tetrachloride, when the aqueous phase/organic solvent volume ratio is 5 and the injection volume in the carbon tube is 20 microl, the sensitivity for selenium is 0.4 ng/ml for 1% absorption. The relative standard deviations are ca. 3%. Interference by many metal ions can he prevented by masking with EDTA. The proposed methods have been applied satisfactorily to determination of Se(IV) and Se(VI) in various types of water.

Selective determination of antimony(III) and antimony(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone by atomic-absorption spectrometry with a carbon-tube atomizer

The extraction behaviour of antimony(III) and antimony(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone in organic solvents has been investigated by means of frameless atomic-absorption spectrophotometry with a carbon-tube atomizer. The selective extraction of antimony(III) and differential determination of antimony(III) and antimony(V) have been developed. With ammonium pyrrolidinedithiocarbamate and methyl isobutyl ketone, when the aqueous phase/solvent volume ratio is 50 ml/10 ml and the injection volume in the carbon tube is 20 mul, the sensitivity for antimony is 0.2 ng/ml for 1% absorption. The relative standard deviations are ca. 2%. Interferences by many metal ions can be prevented by masking with EDTA. The proposed methods have been applied satisfactorily to determination of antimony(III) and antimony(V) in various types of water.

Comparative Study of Zinc Tablet and Sodium Borohydride Tablet Reduction Systems in the Determination of Arsenic, Antimony, and Selenium by Atomic-Absorption Spectrophotometry via Their Hydrides

ZusammenfassungEin atomabsorptionsspektralphotometrisches Verfahren zur raschen und empfindlichen Bestimmung von Arsen, Antimon und Selen über ihre Hydride unter Verwendung der Argon-Wasserstoff-Flamme wurde im Hinblick auf die Reduktionssysteme untersucht. Die Verwendung von Zinktabletten in Kombination mit Zinn(II)-chlorid und Kaliumjodid sowie von Natriumborhydridtabletten wurde geprüft und gefunden, daß in bezug auf Empfindlichkeit und Reproduzierbarkeit keine nennenswerten Unterschiede bestehen. Das Zinksystem bietet jedoch eine bessere Selektivität, besonders im Falle von Arsen.SummaryAn atomic-absorption spectrophotometric method for the rapid and sensitive determination of arsenic, antimony, and selenium with the hydride-argon/hydrogen flame system has been studied. The comparison of the zinc tablet combined with stannous chloride and potassium iodide, and the sodium borohydride tablet reduction systems are described. The sensitivities and precisions of both reduction systems are estimated to be nearly the same. From the results of the comprehensive study on interferences, the zinc system is concluded to be more selective than the sodium borohydride system, which is especially true for arsenic.

Conductance of tris(1,10-phenanthroline)iron(II) and tris(2,2'-bipyridine)iron(II) halides and perchlorates in water and nitrobenzene in relation to solvent extraction of the ion pairs

Conductances of tris(l,10-phenanthroline)iron(II) and tris(2,2-bipyridine)-iron(II) chlorides, bromides, iodides, and perchlorates were measured in water and nitrobenzene at 25°. Experimental data were analyzed by the Fuoss-Edelson and Jenkins-Monk methods for 2:1 electrolytes. The derived parameters indicated that all the salts studied are almost completely dissociated in water, whereas in nitrobenzene, the association constants were of the order expected from electrostatic theory, which was in turn the order of distribution ratios of the ion pairs between water-and nitrobenzene. An approximately linear relationship was obtained between log ka1(0) and log D. It is suggested that for the analysis of the mechanism of the extraction of these ion pairs into nitrobenzene, ionic association in the nitrobenzene phase must be considered an important factor.

Use of transition elements to enhance sensitivity for selenium determination by graphite-furnace atomic-absorption spectrophotometry combined with solvent extraction with the APDC-MIBK system

A microanalytical method for the measurement of selenium in waters and biological materials by a flameless atomic-absorption technique has been developed. The ammonium pyrrolidinedithiocarbamate-methyl isobutyl ketone extraction system is used for separation from interfering materials such as large amounts of alkali and alkaline earth metal salts and mineral acids. The atomic-absorption sensitivity for selenium is found to be enhanced to a large extent by co-extraction of some transition metal ions. Copper(II) has been used successfully as such an additive to diminish the volatility of selenium in the graphite furnace during the ashing step of the atomization cycle. When the aqueous phase/organic solvent volume ratio is 5 and the volume injected into the graphite furnace is 20 mul, the sensitivity for selenium is 0.3 ng/ml for 1% absorption. The relative standard deviation is ca. 2%. Interference by other metal ions is prevented by masking with EDTA. The method has been applied satisfactorily for the determination of minute amounts of selenium in waters and various biological materials.

Thermal properties of tris(1,10-phenanthroline) complexes of iron(II) and nickel(II) salts

Abstract Thermal behaviour of the complexes [M(phen)3]X2·nH2O has been studied in static air and vacuum atmospheres (where M = Fe(II), Ni(II); phen = 1, 10-phenanthroline; and X = Cl, Br, I, SCN). The intermediate derivatives of the thermal decomposition of these complexes having composition M(phen)2X2 are isolated in the furnace of DTA-TG apparatus under vacuum atmospheric conditions. Structures are assigned to these intermediate complexes on the basis of analytical data, reflectance spectra, magnetic moments and X-ray powder diffraction patterns.

Enhancement of Sensitivity for Selenium Determination in Atomic Absorption Spectrophotometry by Introducting Hydrogen Selenide into an Argon-Hydrogen Flame

Abstract The sensitivity for selenium determination with atomic absorption spectrophotometry is enhanced to a large extent by introducing hydrogen selenide gas into an argon-hydrogen flame. As a reducing agent, zinc granular and stannous chloride is successfully used for quantitative and rapid productions of hydrogen selenide from selenium(IV) solution. The sensitivity for 1 % absorption of the signal is estimated to be about 0.02 ppm of selenium.

Differential Determination of Antimony (III) and Antimony (V) by Hydride Generation-Atomic Absorption Spectrophotometry

Abstract From a weakly alkaline solution, antimony (III) was found to be reduced to stibine by sodium borohydride. This paper describes preliminary results for a differential determination of antimony (III) and antimony (V) by hydride generation-atomic absorption spectro photometry with a nitrogen-hydrogen flame. Antimony (III) is determined selectively up to 0.8 μg at pH 8 adjusted with borate buffer under the presence of antimony (V) at the level of 100-fold excess over antimony (III). A detection limit and a relative standard deviation are 10 ng (0.4 ng/mL) and 1.3%, respectively.