Chemical analysis of manganese nodules : Part II. Determination of uranium and thorium after anion-exchange separation

A method is described for the determination of uranium and thorium in manganese nodules. After dissolution of the sample in a mixture of perchloric and hydrofluoric acids, uranium is adsorbed on the strongly basic anion-exchange resin Dowex 1 (chloride form) from 6 M hydrochloric acid. The effluent is evaporated and the residue is taken up in 7 M nitric acid—0.25 M oxalic acid; thorium is then isolated quantitatively by anion-exchange on Dowex 1 (nitrate form). Thorium is eluted with 6 M hydrochloric acid and determined spectrophotometrically by the arsenazo III method. Uranium is eluted from the resin in the chloride form with 1 M hydrochloric acid and then separated from iron, molybdenum and other co-eluted elements on a column of Dowex 1 (chloride form); the medium consists of 50% (v/v) tetrahydrofuran, 40% (v/v) methyl glycol and 10% (vv) 6 M hydrochloric acid. After removal of iron and molybdenum by washing the resin with a mixture of the same composition and with pure aqueous 1 M hydrochloric acid, the adsorbed uranium is eluted with 1 M hydrochloric acid and determined by fluorimetry. The method was used successfully for the determination of ppm-quantities of uranium and thorium in 60 samples of manganese nodules from the Pacific Ocean.     

Chemical analysis of manganese nodules: Part IV. Determination of Nickel after Anion-exchange Separation

A method is described for the a.a.s. determination of nickel in manganese nodules after its separation from interfering metals. After dissolution of the sample in a mixture of perchloric and hydrofluoric acids, manganese, iron, cobalt, copper and other elements are adsorbed on the strongly basic anion exchange resin Dowex 1 (chloride form) from 95% ethanol-5% 12 M hydrochloric acid. The nickel passes into the effluent in which it is determined by a.a.s. with an air-acetylene flame. The method was used successfully for the determination of nickel in numerous samples of nodules from the Pacific Ocean.     

Determination of seven trace elements in natural waters after separation by solvent extraction and anion-exchange chromatography

A method is described for the determination of cadmium, cobalt, copper, manganese, lead, uranium, and zinc in samples of natural waters. After acidification with hydrochloric acid the water sample is filtered and the diethyldithiocarbamates of the trace elements are isolated by extraction with acetone—chloroform (2:5) at pH 5. Following this preconcentration step the metal ions are adsorbed on a column of the strongly basic anion-exchange resin Dowex 1-X8 (chloride form) using as sorption solution a mixture (5:4:1, $\text{v}\text{v}$) of tetrahydrofuran, methyl glycol and 6 M hydrochloric acid. Successive elution is effected with 6 M hydrochloric acid (Co, Cu, Mn and Pb), 1 M hydrochloric acid (U) and 2 M nitric acid (Cd and Zn); the metal ions in the eluates are determined by atomic absorption spectrophotometry (except uranium, which is determined fluorimetrically). The procedure was used to determine the trace-metals in water and snow samples collected in Austria and to analyse a sample of sea water from the Adriatic Sea.     

Chemical analysis of manganese nodules: Part III. Determination of Thallium,Molybdenum and Vanadium after Anion-Exchange Separation

A method is described for the determination of thallium, molybdenum and vanadium in manganese nodules. After dissolution of the sample in a mixture of perchloric and hydrofluoric acids, thallium and molybdenum are adsorbed on the strongly basic anion-exchange resin Dowex 1 (chloride form) from 6 M hydrochloric acid containing bromine. Molybdenum is eluted with 2 M perchloric acid-1 M hydrochloric acid and determined by a.a.s. with a nitrous oxide—acetylene flame. Thallium is eluted with an aqueous solution of sulphur dioxide and, after evaporation of the eluate, this element is determined by a.a.s. with an air—acetylene flame. The same method is used for the assay of vanadium in the 6 M hydrochloric acid effluent. The method was used successfully for the determination of thallium, molybdenum and vanadium at the ppm level in numerous samples of nodules from the Pacific Ocean and Lake Michigan.     

Determination of five trace elements in sea water after separation by anion-exchange chromatography

Summary A preconcentration technique involving anion-exchange in a thiocyanate medium has been developed for the determination of traces of vanadium, cobalt, copper, zinc, and cadmium in sea water. A conventional, small column containing a strongly basic anionexchange resin Amberlite CG 400 in the thiocyanate form allows the five trace metals to be concentrated from a 11 of sea water sample adjusted to 0.1M in thiocyanate and 0.1M in hydrochloric acid. Sorbed metals can be recovered simultaneously by elution with 140 ml of 2M perchloric acid. A stepwise elution technique is also developed, which permits removal of vanadium-copper-cobalt as a group, zinc, and cadmium to improve the selectivity of the separation. A simple scheme of separation for vanadium, copper, and cobalt is given, so that spectrophotometric determinations of these metals even with nonselective reagents may be feasible. Results are quoted on the preconcentration and subsequent spectrophotometric determination of the five metals in brine and sea waters.     

Determination of uranium in natural waters after anion-exchange separation

A method is described for the determination of uranium by fluorimetry and spectrophotometry in samples of natural non-saline waters. After acidification with hydrochloric acid, the water sample is filtered and, following the addition of ascorbic acid and potassium thiocyanate, passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (thiocyanate form). On this exchanger uranium is adsorbed as an anionic thiocyanate complex. After removal of iron and other coadsorbed elements by washing first with a mixture consisting of 50 vol.% tetrahydrofuran, 40 vol.% methyl glycol and 10 vol.% 6 M hydrochloric acid, and then with pure aqueous 6 M hydrochloric acid, the uranium is eluted with 1 M hydrochloric acid. In the eluate, uranium is determined fluorimetrically or by means of the spectrophotometric arsenazo III method. The procedure was used for the routine determination of uranium in water samples collected in Austria.     

Multi-element analysis of manganese nodules by atomic absorption spectrometry without chemical separation

Five manganese nodules, including the USGS reference nodules A-1 and P-1, were analyzed for Co, Cu, Fe, K, Mg, Mn, Na, Ni and Zn without prior chemical separation by using a simultaneous multi-element atomic absorption spectrometer with an air—cetylene flame. The nodules were prepared in three digestion matrices. One of these solutions was measured using sixteen different combinations of burner height and air/acetylene ratios. Results for A-1 and P-1 are compared to recommended values and results for all nodules are compared to those obtained with an inductively coupled plasma. The elements Co, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn are simultaneously determined with a composite recovery for all elements of 100 ± 7%, independent of the digestion matrices, heights in the flame, or flame stoichiometries examined. Individual recoveries for Co, K, and Ni are considerably poorer in two digests than this composite figure, however. The optimum individual recoveries of 100 ± 5% and imprecisions of 1–4%, except for zinc, are obtained when Co, K, Mn, Na and Ni are determined simultaneously in a concentrated digest, and in another analytical sequence, when Cu, Fe, Mg, Mn and Zn are measured simultaneously after dilution. Determination of manganese is equally accurate in the two sequences; its measurement in both assures internal consistency between the two measurement sequences. This approach improves analytical efficiency over that for conventional atomic absorption methods, while minimizing loss of accuracy or precision for individual elements.     

Determination of hexavalent chromium in welding fumes by GFAAS after liquid anion-exchange separation

Summary The interferences due to the presence of large amounts of atoms such as iron, sodium, cadmium, magnesium and potassium on the ETA-AAS determination of trace amounts of chromium(VI) in welding fumes are discussed. An ion-exchange liquid extraction separation procedure is proposed to overcome these interactions. Results obtained on international standards of welding fumes, distributed in two round robin experiments, are also presented.

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Bestimmung von Chrom(VI) in Schweißereidämpfen nach Abtrennung mit Hilfe eines flüssigen IonenaustauschersUntersuchung der Störungen

     

Lattice vibrations of manganese oxides. Part I. Periodic structures

Raman scattering (RS) and Fourier transform-infrared (FT-IR) spectroscopy have been applied to the structural characterisation of manganese dioxides (MDOs). A variety of synthetic battery-grade MDOs are investigated for comparison to the natural phases. The RS and FT-IR spectra are analysed on the basis of the local environment in the MDO structures considering the vibrations of the MnO6 octahedral building the lattices. The vibrational modes of the MnO6 units expand over 400-650 cm(-l) with additional bands in the low-wavelength region. Structural trends are deduced from the comparison of the vibrational spectra of the MDO phases investigated: birnessite, bixbyite, coronadite, groutite, hausmannite, hollandite, manganosite, pyrolusite, ramsdellite, romanechite, spinel, and todorokite.     

Determination of thorium and uranium in activated concrete by inductively coupled plasma mass spectrometry after anion-exchange separation

A sensitive analytical method was established for the determination of Th and U in activated concrete samples. The method combines an anion-exchange separation step with an ICP-MS determination technique. In the ICP-MS measurement, a few μg mL^–1 of Al and Ca, a few ng mL^–1 of Mn, La, Ce, Nd and Pb and pg mL^–1 amounts of Li, Zr, Nb and Ba coexisting in the anion-exchange fraction of Th and U did not interfere. No adverse interference effects were observed in real sample analyses. The obtained detection limits (3σ, n = 10) of Th and U were 2.3 and 1.8 pg mL^–1, respectively. The analytical precisions for ca. 5 μg g^–1 Th and ca. 1 μg g^–1 U in real activated concrete samples were equally less than 7% RSD. The accuracies obtained by the analysis of GSJ rock standard samples were –18.1 to 0.4% for the Th determination and –14.0 to –5.7% for the U determination. The method uses the conventional absolute calibration curve. The internal standard calibration is unnecessary.     

Cathode-ray-excited emission spectroscopic analysis of trace rare earths: Part I. Qualitative studies

Line emissions from f-f transitions in rare earths contained in a matrix are obtained by excitation with cathode rays. The distinctive energy of these emissions is utilized to detect the presence of trace amounts of rare earths, and non-destructive identification of such traces is carried out quickly by comparison with a derived hauptlinien spectrum. Matrix effects, masking interferences and the utilization of line shape are discussed.     

Determination of thorium and uranium in activated concrete by inductively coupled plasma mass spectrometry after anion-exchange separation

A sensitive analytical method was established for the determination of Th and U in activated concrete samples. The method combines an anion-exchange separation step with an ICP-MS determination technique. In the ICP-MS measurement, a few μg mL^–1 of Al and Ca, a few ng mL^–1 of Mn, La, Ce, Nd and Pb and pg mL^–1 amounts of Li, Zr, Nb and Ba coexisting in the anion-exchange fraction of Th and U did not interfere. No adverse interference effects were observed in real sample analyses. The obtained detection limits (3σ, n = 10) of Th and U were 2.3 and 1.8 pg mL^–1, respectively. The analytical precisions for ca. 5 μg g^–1 Th and ca. 1 μg g^–1 U in real activated concrete samples were equally less than 7% RSD. The accuracies obtained by the analysis of GSJ rock standard samples were –18.1 to 0.4% for the Th determination and –14.0 to –5.7% for the U determination. The method uses the conventional absolute calibration curve. The internal standard calibration is unnecessary. Received: 14 March 1999 / Revised: 13 July 1999 / Accepted: 15 July 1999     

Cathode-ray-excited emission spectroscopic analysis for trace rare earths : Part II. Determination of europium

Trace amounts of europium can be determined quantitatively in situ by excitation with cathode rays (electrons) and detection of europium transitions. Europium can then be determined from a standard plot of intensity vs. concentration. Matrix effects, voltage effects, detection lines, and rare-earth and first-transition-group interferences are discussed. While the detection limit of europium under normal conditions is about 0.1 p.p.m., optimizing the above effects yields an ultimate detection limit, by extrapolation, of about 0.005 p.p.m.     

Atomic-absorption determination of vanadium and molybdenum in tap water and mineral waters after anion-exchange separation.

A method is described for the determination of vanadium and molybdenum in samples of tap and bottled mineral water. After acidification with citric acid the water sample is heated to about 80°C to remove CO₂; sodium citrate and ascorbic acid are added and the resulting solution of pH 3 is passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (citrate form) on which both vanadium and molybdenum are adsorbed as anionic citrate complexes. Vanadium is eluted with 6 M hydrochloric acid; molybdenum is recovered with 2 M perchloric acid-1 M hydrochloric acid. Vanadium and molybdenum are determined in the eluates by atomic-absorption spectrometry. The samples analysed contained 0.1–0.9 μg l^?1 vanadium and 0.2–13 μg l^?1 molybdenum.     

Determination of cadmium, copper and lead in natural waters after anion-exchange separtion.

A method is described for the determination of cadmium, copper and lead in samples of natural non-saline waters. After acidification with hydrobromic acid, the water sample is filtered and, following the addition of ascorbic acid, passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (bromide form). On this exchanger cadmium(II). copper(I) and lead(II) are adsorbed as anionic bromide complexes. After elution of these elements with 1 M nitric acid, the determinations by atomic absorption spectrometry are carried out in a medium consisting of 90% ($\text{v}\text{v}$) methanol and 10% ($\text{v}\text{v}$) 1.5 M hydrobromic acid. The procedure was used for the routine determination of cadmium, copper and lead in water samples collected in Austria.     

Essential serum trace metals: I. Determination of iron

Studies of serum iron determination have been described using sensitive color reagents of high molar absorptivities. Each selective reaction for iron is strengthened by means of complexing molecules which eliminate trace metal interferences. One ligand. 4-(2-pyridylazo)-resorcinol, exhibits two sensitive peaks, either of which can be used to determine iron quantitatively if an interference is present at one wavelength, or to qualitatively help ensure by ratio measurement that iron is the only metal determined. The second ligand, 2,4-bis(5,6-diphenyl-1,2,4-triazin3-yl) pyridinetetrasulfonic acid, is not only sensitive but has the capability of measuring iron, copper, or both by a judicious choice of selective conditions. Each compound has a useful potential in either discrete sampling or on-stream automation.     

Determination of trace amounts of nickel, manganese, cobalt, and zinc in environmental samples after separation and preconcentration by use of polyacrylic acid/alumina sorbent

Manganese, nickel, cobalt, and zinc are elements that appear together in many real samples. In this work, a simple, rapid, and sensitive method has been used for the simultaneous separation and preconcentration of trace amounts of these elements using water-soluble polyacrylic acid on alumina as a sorbent in a glass column system. A solution containing Mn, Ni, Co, and Zn was passed through the column at pH 7, and desorption was carried with 5.0 mL of 0.03 M nitric acid. Linearity was maintained between 0.25-5.0 x 10(3), 0.04-6.0 x 10(3), 0.10-8.0 x 10(3), and 0.028-1.0 x 10(3) ng/mL for Ni, Mn, Co, and Zn, respectively, in the original solution. Eight replicate determinations of a mixture containing 1.0 microg/mL of each of the elements in the final solution gave relative standard deviations of 1.4, 1.5, 2.4, and 1.2% for Ni, Mn, Co, and Zn, respectively. The sorption capacities for Mn (mg/g sorbent) obtained were 16.0 for Mn, 9.0 for Ni, 12.0 for Co, and 10.0 for Zn. By using 5.0 mL elution solution, preconcentration factors of 400, 500, 700, and 460 could be obtained for Ni, Mn, Zn, and Co, respectively.     

Determination of hexavalent chromium in bile by electrothermal atomization atomic-absorption spectrophotometry and liquid anion-exchange separation

Summary We report an electrothermal atomization atomic absorption spectrophotometric (ETA-AAS) method for the selective determination of Cr(VI) in rat bile. The method gives reproducible results (the c. v. ranged from 3.6% to 4.1% for low and high Cr(VI) bile samples respectively) and the recovery data are high varying from 98.6% to 98.7%. No detectable amounts of Cr(VI) (<0.2ppb) suggests that available chromium in rat bile samples was present as Cr(III).

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Bestimmung von Chrom(VI) in Galle durch elektrothermale Atomabsorptions-Spektrophotometrie und Anionenaustausch

Zusammenfassung Über die selektive Cr(VI)-Bestimmung in Rattengalle mit Hilfe elektrothermaler AAS wurde berichtet. Das Verfahren gibt reproduzierbare Werte (3,6% bzw. 4,1% Fehler für niedere bzw. hohe Gehalte). 98,6 bzw. 98,7% des wahren Wertes wurden wiedergefunden. Lag die Menge Cr(VI) unter 0,2 ppb, so ist dies ein Hinweis auf das Vorhandensein von Cr(III).