Paru J. Purohit

Electrothermal atomisation atomic absorption spectrometric determination of silver, beryllium, calcium, iron, lead and tin in uranium without preliminary separation

Electrothermal atomisation atomic absorption spectrometric methods have been developed for the direct determination of Ag, Be, Ca, Fe, Pb and Sn in uranyl nitrate solution. Using 5-µl sample aliquots containing 100 µg of uranium, the detection limits for the analytes vary between 0.1 and 25 p.p.m. (on a uranium mass basis). The precision of determinations at an intermediate concentration was calculated to be better than 9% RSD. Interference studies carried out include the effect of the build-up of uranium in the atomiser and the effect of concomitant and major impurities on the analyte absorbance. A measure of the high accuracy of the determinations can be inferred from the analysis of a set of NBL reference standards.

Electrothermal vaporization — inductively coupled plasma-atomic emission spectrometry for trace metal determination in uranium and thorium compounds without prior matrix separation

Abstract The electrothermal vaporization (ETV) mode of sample introduction into inductively coupled plasma (ICP) has been examined for its suitability for the analysis of trace metals in uranium and thorium compounds without prior chemical separation of the matrices using atomic emission spectrometry (AES). The ETV interfaced with an ICP torch adapted for glove box operation, has led to determination of sub-nanogram amounts of Al, Be, Ca, Cd, Co, Cr, Cu, Mg, Mn, Na, Ni, Zn, Dy, Eu, Gd and Sm using 10 μl of the sample aliquot containing 200 μg of U/Th matrix with a precision of 1–2%RSD. The results obtained here especially for rare earths in the presence of the matrix are of significance.

Electrothermal atomic absorption spectrometric determination of lithium, sodium, potassium and copper in uranium without preliminary chemical separation

Abstract Graphite furnace atomization is used for the direct determination of Li (0.25–4 ppm), Na (8–70 ppm), K (20–300 ppm) and Cu (0.5–25 ppm) in uranium dissolved in nitric acid, with relative standard deviations of 4–9%. Only iron seriously depresses the signals from the alkali metals.

Direct determination of beryllium, copper and zinc in AlU matrices by electrothermal atomization atomic-absorption spectrometry

An atomic-absorption spectrometric method with electrothermal mode of atomization has been developed for the direct determination of Be, Cu and Zn in AlU (3:1) matrix samples without prior chemical separation of the major matrix. The studies carried out include the effect of the matrix on the analyte absorbance, optimization of sample aliquot and other experimental parameters, and analysis of a number of synthetic samples. Nanogram amounts of the analytes can be determined with a solution aliquot of 5 microlitres containing 25 micrograms of the sample with a precision of 6% or better. The analytical range obtained for these analytes is Be: 2-20 mug/l., Cu: 20-200mug/l. and Zn: 1-40mug/ml in the AlU matrix. The analysis of synthetic samples has shown good agreement with their added contents.

Trace metal assay of thorium oxide by atomic emission spectrometry

SummaryAn Atomic Emission Spectrometric (AES) method has been developed for the direct determination of twenty-two metallic elements at trace concentrations in thorium oxide. The method is based on the use of a d.c. arc — carrier distillation technique with 12% composition of a mixed carrier, viz. AgCl+SrF2 in 5:1 proportion, and is equally applicable to both volatile and refractory analytes. A direct reading emission spectrometer with computerised data acquisition and processing facility has been used in these studies. The standardisation procedure includes study of volatilisation/excitation characteristics of the analyte elements to optimise choice and proportion of the carrier and signal integration time apart from optimisation of other experimental parameters such as arc current, viewing position of the arc plasma, sample charge etc. The detection limits for the analytes lie in the range 0.1–50 ppm while the precision of determinations is better than 15% for most of the elements as evaluated from the repetitive analyses of spiked samples.

Solid Sampling Approach in Inductively Coupled Plasma Atomic Emission Spectrometry for the Determination of Four Lanthanides With High Sensitivity

A solid sampling technique was developed for the ICP-AES determination of ultra-trace amounts of lanthanides chemically separated from U/Pu fuel materials. An essentially dc arc approach of using a buffer–carrier mixture of graphite–AgCl (4+1) was adopted to facilitate volatilization of the lanthanides. A 20 µl volume of lanthanide solution is loaded on 20 mg of carrier–buffer mixture placed in the crater of a Scribner–Mullin type of electrode system, evaporated under an IR lamp and introduced into the running argon plasma using a modified plasma torch assembly. The near total introduction of sample vapour into the plasma allows the determination of Dy and Eu at the 0.4 ng level and Gd and Sm can be determined at the 1 and 2 ng levels, respectively, with a precision of 10% RSD. The method is free from interferences due to the presence of concomitant lanthanides and common metals and has a significantly high tolerance to the presence of refractory U–Pu matrices.

Electrothermal atomization atomic absorption spectrometric determination of trace metals in uranium-plutonium fuel materials

SummaryAtomic absorption spectrometric methods using the electrothermal mode of atomization developed for the determination of Ag, Be, Ca, Cd, Cr, Co,Cu, Fe, Li, Mn, Na, Ni, Sn and Zn in (U, Pu) solution with 4% plutonium have been described. The carbon rod atomizer has been adapted for glove box operation to enable handling of plutonium containing solution samples. Multielement solution standards with graded concentrations of the analytes and fixed concentration of the matrix are used in the standardization process. Nanogram to sub-nanogram quantities of the analytes have been determined with a precision of better than 9% RSD using 5 μl of the sample aliquots.

Low level determination of metallics in graphite by analytical spectroscopy

Abstract Analytical atomic absorption/emission spectrometric methods have been developed for determination of 22 metallics at low concentration levels in high purity graphite material required in nuclear fuel industry. Of these, 21 metallics viz., Al,B, Be, Ca, Cd, Cr, Co, Cu, Fe, Li, Mn, Mo, Mg, Ni, Pb, Sn, Si, Ti, V, W and Zn are determined at trace concentration levels by D.C. arc Atomic Emission Spectrometric method using carrier excitation technique with a 6% carrier mixture of AgCl and NaF in a 5:1 proportion. Using the standardized procedure B, Be and Cd can be determined at 0.1 ppm concentrations while most of the other elements could be determined at 5–50 ppm concentrations. The detection limit for W was however 100 ppm. The precision of the method has been better than 20% RSD. The determination of silver is carried out by Electro-Thermal Atomization Atomic Absorption Spectrometric (ETA-AAS) technique by removal of graphite matrix by heating the sample in air at 850°C and dissolution of the resid...

Direct determination of magnesium, manganese, nickel and zinc in uranium by electrothermal AAS

ZusammenfassungDas beschriebene AAS-Verfahren (mit Graphitofen-Atomisierung) wurde zur direkten Bestimmung von 1–20 ppm Mg, 1–30 ppm Mn, 1–50 ppm Ni sowie 10–400ppm Zn in Uranlösungen eingesetzt. Die Proben wurden in Salpetersäure aufgelöst (20 mg/ml U) und aliquote Anteile direkt der AAS-Messung zugeführt. Bruchteile von Nanogrammen können in 100μg U mit Standardabweichungen von besser als 9% bestimmt werden. Probe und Standard müssen jedoch dieselbe Konzentration an U aufweisen. Das Verfahren ist schnell und genau durchführbar und wurde mit Hilfe von zertifiziertem U3O8-Referenzmaterial überprüft. Die Gegenwart von 9 mg Resturan in der Graphitröhre oder ppm-Mengen von 22 Begleitelementen oder 1000 ppm Ca, Fe, Si und Zn in der Probe verursachen keine Störung. 1000 ppm Fe stören jedoch die Bestimmung von Mg und Mn.SummaryAn atomic absorption spectrometric method with the graphite furnace atomization is described for the direct determination of magnesium (1–20 ppm), manganese (1–30 ppm), nickel (1–50ppm) and zinc (10–400ppm) in uranium solutions. The uranium samples were dissolved in nitric acid, with uranium concentration being 20 mg ml−1. Five microlitre sample aliquots were atomized directly from the graphite furnace for each measurement. Determination of these analytes at fractional nanogram and nanogram levels is possible in the presence of 100μg uranium sample with relative standard deviations better than 9%. However, sample and standard solutions must contain the same concentration of uranium matrix. The method is rapid and accurate as checked by analysing the certified NBL U3O8 reference samples. Presence of upto 9 mg of residual uranium in the carbon tube or ppm concentrations of 22 concomitant metallic elements or even 1,000 ppm each of calcium, iron, silicon and zinc in the sample did not cause any significant interference. However, the interference due to 1,000 ppm of iron on magnesium and manganese was found to be significant.

On atomization of calcium, magnesium and antimony from ThO2matrix by atomic absorption spectrometric techniques

Atomic Absorption Spectrometric methods (AAS) developed for the direct determination of Ca and Mg using flame-AAS technique have linear ranges of 0.1-2.0 μg/ml and 0.025-0.4 μg/ml with thorium concentrations optimized at 2.5 and 0.5 mg/ml, respectively, while the analytical range obtained for Sb using electrothermal-AAS technique is 0.002-0.1 μg/ml with Th sample aliquot of 2.5 mg/ml. The precision of determinations for both the techniques as evaluated from analyses of synthetic samples is 5% RSD or better. Probable mechanism for atom formation for Sb has been discussed in detail. In addition, role of chemical modifiers in enhancing the analyte signal has also been discussed.