Accumulation and distribution of elements in rice /seed,brand layer,husk/ by neutron activation analysis

Various rice samples /seed, brand layer, husk/ from Vietnam were analyzed for Se, Hg, Cr, Ni, Sc, Rb, Fe, Zn and Co by neutron activation analysis. The concentration values found /seed/ were the following: Se 0.04–0.07 ppm, Hg 0.02–0.07 ppm, Cr 2.13–8.65 ppm, Ni 1.56–4.95 ppm, Sc 0.02–0.06 ppm, Rb 0.84–2.71 ppm, Fe 26.31–96.07 ppm, Zn 10.65–27.39 ppm and Co 0.02–0.15 ppm. The values were reported in ppm /dry weight/. Statistical analysis /t-test, t=0.05/ showed that the content of elements varies between sorts of rice; the content of Rb, Fe, Ni, Cr of rice husk was significantly higher than in rice seed and brand layer.     

Neutron activation analysis of asbestos from Canada

Concentrations of Al, Au, Br, Ce, Cl, Co, Cr, Fe, K, La, Mg, Mn, Na, Ni, Sb, Sc, Sm, Srm and V were determined in 6 samples of asbestos from Canada. They were equal to (in ppm): Al 1660–3430; Au 0.03–0.04; Br 3.1–11.7; Ce 1.7–4.8; Cl 116–331; Co 35–83; Cr 200–2060; Fe 29300–42200; K 125–867; La 0.28–1.03; Mg 24–25.9%; Mn 418–545; Na 364–1610; Sb 0.65–1.46; Sc 3.73–5.57; Sm 0.09–0.3; Sr 26.7–41.4; V 8.4–14.3. Five toxic elements were found in asbestos; Cr, Mn, Ni, Sb and V.     

Trace elements analysis in rice

Various rice species, marketed in Austria, were analyzed for their Se, Cr, Ni, Rb, Fe, Co, Cs, Ag and Hg contents by neutron activation analysis. The concentration values found for Se ranged between 0.023 and 0.265 ppm, for Cr 0.540–1.875 ppm, for Ni 0.359–0.965 ppm, for Rb 1.604–6.400 ppm, for Fe 24.3–139.8 ppm, for Co 0.026–0.055 ppm, for Cs 0.016–0.032 ppm, for Ag 0.0006–0.0034 ppm, for Hg 0.003–0.023 ppm. Statistical analysis showed in the majority of cases that there is a significant difference in Se, Cr, Ni, Rb, Fe, Co, Hg contents but not in Cs. Highest values of Se and Fe were found in rice from Belgium /long seed, super patna/, whereas the Cr concentration was the highest in rice from Thailand /siam patna/. Ni was highest in rice from Uncle Ben's, Rb in Kresto from USA.     

Concentration of Cr,Fe, Co and Zn in some Nigerian food grains

Elemental analysis of some Nigerian grains for cobalt, zinc, iron, and chromium, was done by thermal NAA. The concentration of these essential trace elements were found as follows: rice /0.18–0.98 ppm Cr, 27–307 ppm Fe, 0.133–0.237 ppm Co, 12.4–17.8 ppm Zn/; soyabean /0.32–0.59 ppm Cr, 67–81 ppm Fe, 0.244–0.358 ppm Co, 42–45 ppm Zn/; maize /0.05–0.75 ppm Cr, 22.7–47.6 ppm Fe, 0.20–0.65 ppm Co, 15.8–33.4 ppm Zn/; ground-nut /0.22–2.02 ppm Cr, 27.2–34.8 ppm Fe, 0.08–1.73 ppm Co, 24.3–38.2 ppm Zn/. No pattern was established for the elemental concentration in the grain samples. The result obtained suggest that an average diet of these grains will provide an adequate concentration of these essential elements.     

AAS-Bestimmung von Eisen, Nickel, Kobalt, Mangan und Chrom in Wolfram und Molybd?n

Zusammenfassung Das Atomabsorptionsverhalten von verschiedenen Metallen (Fe, Ni, Co, Mn, Cr) in Wolfram und in Molybdän wurde untersucht. Eine gegenseitige Störung dieser Elemente wurde nicht beobachtet. Ferner wurde der Einfluß von Dopsubstanzen, wie Alkali, Calcium, Aluminium oder Silicium auf das Absorptionsverhalten untersucht. Die Metalle Fe, Ni, Co, Mn und Cr lassen sich ohne vorherige Trennungsoperationen in Wolfram oder Molybdän bestimmen. Die Empfindlichkeit betrug etwa 0,10–0,30 g/ml oder 5–20 ppm im festen Metall.

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AAS-determination of iron, nickel, cobalt, manganese and chromium in tungsten and molybdenum

Results of the atomic-absorption behaviour of several metals (Fe, Ni, Co, Mn, Cr) in tungsten and in molybdenum are reported. No mutual interference of these elements has been observed. Furthermore the influence of dope-elements, as alkali, calcium, aluminium or silicon, has been investigated. AAS can be applied without prior separation procedure for the determination of Fe, Co, Ni, Mn and Cr in tungsten and in molybdenum. The sensitivity found was in the range 0.10–0.30 g/ml or 5–20 ppm in the solid material, respectively.

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Anerkennung. Für die sorgfältige Durchführung der Analysen danke ich Frau E. U. Stamer.     

Neutron activation analysis of major and trace elements in crude petroleum

We have determined the concentration of 25 trace elements in crude petroleum from seven Libyan oil fields by instrumental neutron activation analysis. Crude oil samples were irradiated with a thermal neutron dose rate of 10¹² and 10¹³ n·cm^–2·s^–1 in the Tajoura research reactor. The concentration of U, Br, Mg, Cu, Na, V, Cl, Al, Mn and Ca is in a range of 0.015 to 84 ppm and that of sulphur of 0.12 to 1.8%. The elements Sc, Cr, Ni, Fe, Co, Zn, Ag, Se, Sb, Ba, Cs, Yb, Hf and Hg have a concentration range of 0.009 to 8747 ppb. The coefficients of variation are within 10%. The elements V and Ni occur as both porphyrin and non-porphyrin and the ratio of these two forms varies over a wide range. The V/Ni ratios are located between 0.17 and 6.67, which are comparable to the reported values for the crude oils from other countries.     

Estimation of trace metals in pure graphite by emission spectroscopy

Summary A direct emission spectrographic method for the estimation of Al, B, Ca, Cd, Co, Cr, Fe, Mg, Mn, Mo, Ni, Pb, Si, Sn, V and Zn in graphite at ppm concentrations has been developed. The effect of different carriers, was investigated and NaF at 1% concentration was found most suitable for the estimations. Ten milligram charge of standards and samples contained NaF as carrier and palladium as internal standard. The spectra were excited in d.c. arc carrying 13 amp current for 25s and photographed on 3.4 M Ebert Grating Spectrograph, on S.A.1 plates in the region 2200–3400 Å. The detection limits lie in the range of 0.25–10 ppm for different elements analysed with precision of 20% or better. The limits obtained here for Ca, Co, Fe and Zn are lower than those reported earlier in the literature.

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Emissionsspektrographische Bestimmung von Metallspuren in reinem Graphit

Zusammenfassung Eine Methode zur direkten Bestimmung von Al, B, Ca, Cd, Co, Cr, Fe, Mg, Mn, Mo, Ni, Pb, Si, Sn, V und Zn im ppm-Bereich in Graphit wurde ausgearbeitet. Verschiedene Trägermaterialien wurden geprüft und 1% NaF wurde als optimal gefunden. Palladium diente als innerer Standard. Zur Anregung wurde der Gleichstrombogen benutzt (13A, 25s; 3,4M Ebert Gitta-Spektrograph, S.A. 1 Platten, 2200–3400 Å). Die Nachweisgrenzen liegen im Bereich von 0.25–10 ppm (Genauigkeit 20% oder besser). Die Nachweisgrenzen für Ca, Co, Fe und Zn sind niedriger als die bisher in der Literatur beschriebenen.

     

AAS determination of Co, Ni, Mn and Cr in ores, concentrates and dusts from copper metallurgy after matrix elements separation by extraction

Summary A method has been developed for the AAS determination of Co, Ni, Mn and Cr in ores, concentrates and dusts of copper metallurgy at the 10^–3–10^–1% level. The matrix elements (Cu, Pb, Zn, Fe) were separated in a two-stage extraction: with MIBK from 6 M HCl solution and with 0.1 M tetrahexylammonium iodide (THAI) in MIBK from 3 M HCl, in form of ion-pairs, without Co, Ni, Mn and Cr losses. Values of r.s.d. were 2.0–6.0%.

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AAS-Bestimmung von Co, Ni, Mn und Cr in Erzen, Konzentraten und Stäuben aus dem Bereich der Kupfermetallurgie nach Abtrennung der Matrixelemente durch Extraction

Zusammenfassung Das beschriebene Verfahren eignet sich für den Bereich von 10^–3 bis 10^–1%. Die Matrixelemente (Cu, Pb, Zn, Fe) wurden als Ionenpaare ohne Verluste an Co, Ni, Mn und Cr mit Hilfe einer zweistufigen Extraktion abgetrennt: mit MIBK aus 6 M HCl-Lösung und mit 0,1 M Tetrahexylammoniumiodid (THAI) in MIBK aus 3 M HCl-Lösung. Die relativen Stadardabweichungen lagen im Bereich von 2,0 bis 6,0%.

     

Spectrographic estimation of impurities in selenium

Summary An emission spectrographic method for the estimation of impurities of Al, As, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Sn, Te, Ti, V, Zn and Zr in high purity selenium at concentrations less than 1 ppm has been developed. The impurities were separated from 1 g of selenium by volatilizing Se from its solution in nitric acid and sulphuric acid. The residue containing impurities was dissolved in small amounts of 6 M HCl and loaded along with the washing on 10 mg mixture containing graphite (90%) and sodium chloride carrier (10%), in the electrode crater. The spectra were excited in a d.c. arc carrying 13 A. The detection limits lie in the range 0.005–0.5 ppm for the different elements. The precision of the method ranges from 7–18% for these elements.

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Spektrographische Bestimmung von Verunreinigungen in Selen

Zusammenfassung Folgende Verunreinigungen werden in hochreinem Selen in Konzentrationen von <1 ppm bestimmt: Al, As, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Sn, Te, Ti, V, Zn und Zr. Das Selen wird von den Verunreinigungen durch Verdampfen abgetrennt (Lösen einer 1 g-Probe in HNO₃/H₂SO₄). Der Rückstand wird in 6 M HCl gelöst und zusammen mit einem Graphit/NaCl-Gemisch (9010) in die Elektrodenbohrung gefüllt. Die Anregung erfolgt in einem Gleichstrombogen von 13 A. Die Nachweisgrenzen liegen im Bereich von 0,005–0,5 ppm, die Genauigkeit beträgt 7–18%.

     

Gas-chromatographic elemental analysis via di(trifluoroethyl)dithiocarbamatochelates

Summary The gas-chromatographic determination of Cr(III) and Cr(VI) in aqueous solution using di(trifluoroethyl)dithiocarbamate as an extracting agent (pH 3) is described. Best results were obtained with a column of OV-25 (3% on Chromosorb HPW, 100–120 mesh, 160–210 C) C₂₈H₅₈ is added as an internal standard. As little as 0.005 ppm of Cr can be determined. Co., Ni, Zn, Cd, Cu, Fe(III) do not interfere. Pb causes tailing, but does not affect the peak height.We thankfully acknowledge the help by DFG (Deutsche Forschungsgemeinschaft) and Verband der Chemischen Industrie. One of the authors (APJ) thanks the Alexander von Humboldt-Stiftung, Bonn, for the award of a fellowship.     

Determination of Au,Sb, As,Br, Na,K, Cd,Mn and Cl in rice from Vietnam by neutron activation analysis

Gold, antimony, arsenic, bromine, sodium, potassium, cadmium, manganese and chlorine were determined by neutron activation analysis in various rice seed, brand layer and husk from Vietnam. The following concentration values were found: Au 0.05–0.28 ppm, Sb 0.05–1.08 ppm, As 0.08–0.94 ppm, Br 0.82–6.72 ppm, Na 16.71–25, 71 ppm, K 2582–5163 ppm, MN 19.26–33.43 ppm, Cd 0.51–2.42 ppm and Cl 205.20–828.61 ppm in rice seed. These elements were also determined in brand layer and rice husk. Statistically significant differences /t=0.05/ in Au, Sb, Cd contents were detected in rice seed and rice husk, as well as brand layer with rice husk.     

INAA of trace impurities in aluminium clads

As a contribution to nondestructive neutron assay of reactor grade aluminium, a number of elements have been investigated qualitatively and quantiatively using a vertical channel in the IRT-5000 reactor with a thermal neutron flux of 7.6·10¹²n·cm^–2·s^–1. The -ray spectra of irradiated samples were analysed with a 30 cm³ Ge(Li) detector connected to an HP-computer and a 4096 channel analyser. The following impurities have been determined: Sc, Ca, Cr, Fe, Ni, Co, Zn, As, Sb, W, Au, Th and U, while Lu and Hf have been determined qualitatively only.     

Determination of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb in natural waters, alkali and alkaline earth salts by electrothermal atomic absorption spectrometry after preconcentration by column solid phase extraction

Methods are described for the determination of trace and ultra trace amounts of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb in natural waters, alkali and alkaline earth salts. Separation and preconcentration of trace metals is achieved by a column solid phase extraction procedure using silica gel modified with derivatives of dithiocarbamates — Na-DDTC (sodium diethyldithio-carbamate and HMDTC (ammonium hexamethylene-dithiocarbamate) as column packing material. The influence of the sorbent preparation procedure on the degree of sorption of the trace analytes is examined for different pH values of the sample solution. Isobutylmethyl ketone (IBMK) is proposed as an effective eluent for quantitative elution of retained metal ions. Optimal instrumental parameters for ETAAS determination of preconcentrated elements in organic eluate are presented. Practical application of sorbents in analysis of natural waters and alkali and alkaline earth salts is demonstrated. Proposed preconcentration procedure combined with ETAAS determination of trace analytes allows the determination of 0.04 g l^–1 Cd, 0.1 g l^–1 Cr, Cu, and Mn and 0.3 g l^–1 Co, Fe, Ni and Pb in natural waters and 1.10^–7% Cd, 3.10^–7% Cr and Mn, 7.10^–7% Co, Ni and Pb and 2.10^–6% Cu and Fe in alkali and alkaline earth salts.     

Extraction and neutron activation analysis of humic substances

Methods are described for the isolation of humaic substances from a soil samples. The produres and based on extractions with sodium hydroxide or sodium pyrophosphate. Four of the humic samples were dried and then analysed by thermal neutron activation analysis. The humic samples along with three standard rocks were irradiated for 15 hours in a flux of 10¹² n·cm^–2·s^–1. Counting was carried out using both a large volume Ge(Li) detector and a high resolution LEP detertor. Quantitative analysis was based on the known element concentrations in the standard rocks. The elements determined were Sc, Cr, Fe, Co, As, Se, Br, Mo, Sb, La, Ce, Eu, Hf, Ta, Th, and U. concentrations ranged from 0.02 ppm (La) to 7900 ppm (Fe).     

Chemical characterization of gas- and oil-bearing shales by instrumental neutron activation analysis

The concentration of As, Ba, Ca, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, K, La, Lu, Mn, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, and Zn were determined by instrumental neutron activation analysis in block shale samples of the New Albany Group (Devonian-Mississippian) in the in the Illinois Basin. Uranium content of the samples was as high as 75 ppm and interfered in the determination of samarium, molybdenum, barium and cerium. In the determination of selenium a correction was made for interference from tantalum. U, As, Co, Mo, Ni and Sb as well as Cu, V and pyritic sulphur which were determined by other methods, were found to correlate positively with the organic carbon content of the samples.     

INAA for control of technology in producing Mo and W

INAA technique for the determination of impurities (O, F, Na, Mg, Al, Si, P, S, K, Sc, Cr, Mn, Fe, Co, Ni, etc.) and of some doping elements in molybdenum and tungsten with detections limits between 10^–12 and 10^–6g/g by using a nuclear reactor and a neutron generator have been developed. The methods have been used to control the products of processing of refractory materials, to study the dynamics of impurities and doping elements at all stages of the production process.     

Heavy metals in selected soils of the semi-arid region of Nigeria

Eight soil profiles developed on crystalline basement complex rocks in the semi-arid region of Nigeria were analyzed for total contents of cesium (Cs), chromium (Cr), cobalt (Co), hafnium (Hf), iron (Fe), lanthanum (La), lutetium (Lu), scandium (Sc), thorium (Th), uranium (U) and ytterbium (Yb). The contents range from 50.3–95.4 Cs, 16.1–58.1 Cr, 0.6–9.0 Co, 9.0–34.8 g g^–1 Hf, 0.31–3.69% Fe, 17.2–60.7 La, 60.4–90.6 Lu, 2.6–12.6 Sc, 8.3–21.5 Th, 4.7–9.2 U and 3.6–92 g g^–1, Yb. Their corresponding means were 68.4, 35.1, 4.0, 19.9 g g^–1, 1.70%, 37.1, 79.4, 6.5, 14.7, 6.7 and 5.0 g g^–1. In general, total Cs, Co, Fe, La, U and Yb increased with further increase with depth. On the other hand, Lu, Sc and Th showed no distinct vertical distribution within the profiles. All eleven elements were correlated with the amounts of clay present in the soils, the correlation being stronger for Cs, Th, Yb, Cr and Lu.     

Determination of trace impurities in semi-conductor grade PCl3 and POCl3-A d.c. arc spectrochemical method

Summary A spectrochemical method for the determination of traces of Al, Co, Cu, Cr, Fe, Mn, Mg, Ni, Pb, Sb, Sn, Ti and V in semiconductor grade PCl₃ and POCl₃ has been developed. 25ml of the sample is evaporated in a stream of nitrogen and the residual phosphoric acid containing the impurities is treated with bismuth nitrate to co-precipitate the impurities on BiPO₄. The phosphate is spectrographically analysed employing the d.c. arc with Ga as the internal standard and LiF as the carrier. The range of concentration determined is 5–200 ppm and the precision of the method in terms of coefficient of variation is 9–20% for the different impurities.

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Bestimmung von Spurenverunreinigungen in Halbleiter-Phosphortrichlorid und -Phosphoroxidchlorid — Ein spektralanalytisches Verfahren mit Gleichstrombogen

Zusammenfassung Ein Verfahren wurde ausgearbeitet zur Bestimmung von Spuren Al, Co, Cu, Cr, Fe, Mn, Mg, Ni, Pb, Sb, Sn, Ti und V in Halbleiter-PCl₃ und-POCl₃. 25 ml der Probe werden im Stickstoffstrom eingedampft und die zurückbleibende Phosphorsäure, die die Verunreinigungen enthält, wird mit Bismutnitrat behandelt, wobei die Verunreinigungen an BiPO₄ mitgefällt werden. Das Phosphat wird spektralanalytisch untersucht (Gleichstrombogen, Ga als als innerer Standard, LiF als Träger). Die Elemente wurden im Bereich von 5–200 ppm analysiert. Der Variationskoeffizient lag zwiwchen 9 und 20%.

     

New spectrometric method for the determination of trace elements in petroleum by double plasma arc source in a graphite tube

Summary A method is described for the determination of trace elements (V, Mo, Ni, Co, Mn, Ag, Be, Sn, Ga, In, Cr) in petroleum, using a double plasma arc source in a graphite tube. The sample is mixed with graphite powder in the ratio 14, heated to 220° C, mixed with 6% NaCl and loaded into graphite electrodes. Petroleum of different origin was successfully analysed (standard deviation 7–11%; limit of detection 0.003 –0.1 ppm).

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Neues Verfahren zur spektrometrischen Bestimmung von Spurenelementen in Erdöl mit Hilfe eines doppelten Plasmabogens im Graphitrohr

Zusammenfassung Bei dem Verfahren wird die Probe im Verhältnis 14 mit Graphit vermischt, auf 220° C erhitzt, mit 6% NaCl versetzt und in Graphitelektroden gegeben. Erdöl verschiedenen Ursprungs wurde mit dem Verfahren analysiert (Standardabweichung 7–11%; Nachweisgrenze 0,003–0,1 ppm). Folgende Spurenelemente wurden erfaßt: V, Mo, Ni, Co, Mn, Ag, Be, Sn, Ga, In, Cr.

     

Aktivierungsanalytische Bestimmung von Verunreinigungen in hochreinem Aluminium

Zusammenfassung Zur Bestimmung geringer Gehalte der Elemente Au, Hg, Cu, Cd, As, Sb, Sn, Ga, Fe, In, Cr, Co, Ni, Mn, Zn, Mo und W in hochreinem Aluminium wurde eine aktivierungsanalytische Methode ausgearbeitet. Bei einer Einwaage von insgesamt etwa 1 g kann die Analyse mit Nachweisempfindlichkeiten zwischen 1 · 10^–6 (Au) und 0,5 ppm (Fe) durchgeführt werden. Die erforderlichen chemischen Trennoperationen werden beschrieben.

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Summary A method is described for the determination of low contents of the elements Au, Hg, Cu, Cd, As, Sb, Sn, Ga, Fe In, Cr, Co, Ni, Mn, Zn, Mo and W in high-purity aluminium by activation analysis. With sample weights of about 1 g sensitivities are obtained between 1 · 10^–6 (Au) and 0,5 ppm (Fe). The chemical separation procedures required are described.

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Den Herren W. Schweighofer und U. Grahmann möchten wir an dieser Stelle für ihre wertvolle Mitarbeit hei der Ausarbeitung und Durchführung der Analysen danken.

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Herrn Prof. Dr. W. Geilmann zum 75. Geburtstag gewidmet.