Rokuro Kuroda

The geochemistry of tin

Abstract In order to obtain more reliable and comprehensive geochemical figures about tin. neutron activation analyses were undertaken for widely selected materials of geochemical interests. Analyses are given for 35 silicic (av. 3.6 ppm Sn). 19 intermediate (av. 1.5 ppm). 3 mafic (av. 0.9 ppm) and 4 ultramafic rocks (av. 0.35 ppm). Data for 10 red clays (av. 4.9 ppm), 3 globigerina oozes (av. 1.5 ppm) and 4 volcanic muds (av. 1.4 ppm), all of them collected from the Pacific Ocean, and 3 red clays of the Japan Sea (av. 4.1 ppm) are also given. Our results on the abundance values for tin in various types of igneous rocks, as well as of red clays. confirm the figures given by Onishi and Sandell (1957). Contrary to the previous information about the geochemistry of tin, we found that tin should be thought of as being distributed as a “trace element” rather evenly throughout the erustal rocks. Pelagic sediments do not show any marked enrichment of tin compared with igneous rocks. The striking similarity in the concentrations of tin in the pelagic argillaceous sediments, terrestrial clays and igneous rocks suggests a mainly terrigenous origin for the deep-sea sediments rather than one involving the submarine weathering of volcanics and pyroclastics. Sea water samples of the Pacific Ocean give the value of 0–81 /tg Sn/1. as an average. The enrichment factor for tin for marine animals is estimated to be about ~2400 to a good order of magnitude.

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry.

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1-0.7 mug/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere.

CATION-EXCHANGE SEPARATION OF SCANDIUM

Abstract A cation-exchange study of scandium is described. The distribution coefficients of scandium and other common metals have been determined by a batch method. The empirical formula of the scandium complex existing in the thiocyanate-hydrochloric acid system is suggested as being Sc(SCN)2Cl. Scandium can be separated from thorium, zirconium, iron, titanium, aluminium and calcium using an ammonium thiocyanate-hydrochloric acid mixture as eluent. Some separation of scandium from the rare earths is also achieved, but the heavier rare earths cannot be separated cleanly.

Ion-exchange separation and spectrophotometric determination of zirconium, thorium, and uranium in silicate rocks with arsenazo III

Abstract A combined chromatographic-spectrophotometric method has been developed for the simultaneous determination of thorium, zirconium and uranium in silicate rocks. After sample decomposition with a mixture of perchloric and hydrofluoric acids, the three metals are precipitated with iron(III) and aluminum hydroxides, and adsorbed by anion-exchange on a Dowex l-column from dilute sulfuric acid containing hydrogen peroxide. The adsorbed thorium, zirconium and uranium are separated by elution with acid ammonium sulfate solution, hydrochloric acid and perchloric acid, respectively. The sorption from sulfate media and subsequent elution provide selective separation of thorium, zirconium and uranium, allowing their direct spectrophotometric determination with arsenazo III. Results on the determination of thorium, zirconium and uranium in standard rocks of the U.S. and Japan Geological Survey are quoted.

A combined ion-exchange spectrophotometric method for the determination of molybdenum and tungsten in sea water

Abstract A combined ion-exchange spectrophotometric method has been developed for the determination of molybdenum and tungsten in sea water. The two elements are adsorbed quantitatively on Dowex 1-X8 (SCN-form) from sea water adjusted to 0.1 M in hydrochloric acid and 0.1 M in ammonium thiocyanate. Molybdenum also can be concentrated quantitatively on Dowex I-X8 (Cl-form) from sea water acidified to 0.1 M. in hydrochloric acid and containing > 6% hydrogen peroxide. In both concentration procedures, molybdenum and tungsten are easily eluted with 0.5 M sodium hydroxide-0.5 M sodium chloride solution. The adsorption and desorption steps provide selective concentration for molybdenum and tungsten, so that molybdenum can be determined spectrophotometrically with dithiol. Tungsten is separated from molybdenum by anion-exchange on DEAE (Cl-form), and can be determined similarly with dithiol. A sea-water sample collected from the Pacific Ocean, off the coast of Kominato, Chiba, gave values of 9.5 ±0.1 μg mo l and 9.3 ±0.2 μg Mo l for the thiocyanate concentration and hydrogen peroxide concentration methods, respectively, with 1-l samples. Duplicate analyses of sea water from the same location as for molybdenum, gave values of 0.115 and 0.116 μg l for tungsten, on a 20-l sample basis.

Separation of platinum and palladium from base metals with a weakly basic cellulose ion exchanger

Abstract Platinum(IV) and palladium (II) are strongly adsorbed on the weakly basic cellulose ion exchanger DEAE from dilute thiocyanate media, while most other metal ions do not show any marked tendency to adsorb from the same media. It is possible to separate and concentrate the noble metal ions from a large quantity of base metals such as iron, cobalt, nickel, copper, zinc and lead. As little as 1 mg of platinum(IV) and/or palladium (II) can be quantitatively separated from as much as 20–25 g of base metals on a small column of DEAE (thiocyanate form). The noble metal ions adsorbed are easily stripped from DEAE.

Simultaneous determination of iron(III) and total iron by flow injection analysis using kinetic spectrophotometry with tiron

Two flow injection analysis systems have been developed for the simultaneous spectrophotometric determination of iron(III) and total iron using Tiron as the colour developing reagent. The first system uses a single detector with two flow cells aligned with the same optical path to yield two peaks corresponding to iron(III) and total iron in the sample. The sample through put is high (60 samples h–1) with a precision of 0.35% for iron(III) and 0.55% for total iron. The second system is a multi-detection system which allows 30 samples to be analysed per hour with the advantage of much simpler instrumentation.

Anion-exchange separation and spectrophotometric determination of molybdenum and tungsten in silicate rocks

A combined ion-exchange spectrophotometric method has been developed for the determination of molybdenum and tungsten in silicate rocks. After the decomposition of samples with a mixture of sulphuric, nitric and hydrofluoric acids, traces of molybdenum and tungsten are separated from other elements by anion-exchange in acid sulphate media containing hydrogen peroxide. The adsorbed molybdenum and tungsten can easily be stripped from the column by elution with sodium hydroxide-sodium chloride solution. The adsorption and desorption steps provide selective concentration of molybdenum and tungsten, allowing the simultaneous spectrophotometric determination of the two metals with dithiol. Results on the quantitative determination of molybdenum and tungsten in the U.S. Geological Survey standard samples are included.

Values for trace elements in G-1 and W-1 with neutron activation analysis

Trace elements were determined in Japanese granite (G-1) and basaltic (W- 1) rocks by neutron activation analysis. The elements determined are antimony, arsenic, copper, europium, gold, lanthanum, samarium, scandium, and uranium. The results are compared with previous determinations. (N.W.R.)

Ion interaction chromatography of nitrilotriacetatocomplexes of the rare earth elements with post-column reaction detection.

The chromatographic behaviour of nitrilotriacetatocomplexes of the rare earth elements (Sc, Y and lanthanides) on a reversed phase ODS column has been investigated in the presence of 1-octane-sulphonate. There is a great difference in selectivity for the ODS among the rare earth nitrilotriacetato-complexes. Concentration gradient elution with nitrilotriacetic acid (0.005-0.050M, pH 3.0) that contains 0.01M 1-octanesulphonate allows the rare earth elements to be separated from each other within 30 min at room temperature, except a Gd-Eu pair which is eluted together. Yttrium elutes at about 10 min between samarium and neodymium. Detection and quantitation of the rare earth elements can be achieved by post-column reaction with Chlorophosphonazo III in acid media at 700 nm.