Naina Raje

Proconcentration of trace elements from high-purity thorium and uranium on Chelex-100 and determination by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction

Abstract Preconcentration of trace impurities form large-sized samples of uranium metal and thorium oxide using a small column of Chelex-100 followed by their determination using graphite furnace atomic absorption spectrometry (GFAAS) is reported. A 0.5–10-g amount of the sample (uranium metal or thorium oxide) was dissolved, complexed with ammonium carbonate and subjected to the ion-exchange procedure. The retained analytes were eluted with 2–4 M nitric acid and brought to a small volume for a final dilution to 10-25 ml for their determination using GFAAS. The validity of the separation procedure and recoveries at μg kg −1 levels was checked by standard addition; the recoveries were > 95%.

Preconcentration and determination of mercury in high purity arsenic

Abstract An analytical procedure for the determination of trace amounts of mercury in high purity arsenic metal/oxide, widely used in electronic devices, is presented in this manuscript. Pre-concentration of mercury from a large amount of the matrix on a small amount of anion exchanger in hydrochloric acid medium was used to enrich the analyte concentration, followed by its determination using neutron activation analysis (NAA). A detailed study was carried out for the quantitative separation of the analyte from the matrix along with the precautions to be considered for the accurate determination of this volatile element. The separation of the analyte was quantitative and the validity of the procedure was confirmed by tracer studies, standard addition of the analyte to the matrix and by analyzing high purity arsenic for which certified values are available. The overall reproducibility of the separation procedure was 2–10%.

Trace element characterization of high purity gallium

Abstract An ion exchange method is described for the quantitative separation of ca. twenty trace elements from high purity gallium metal. 0.5–2 g of matrix is dissolved and subjected to a separation procedure using an anion exchanger in hydrochloric acid followed by sodium hydroxide medium to preconcentrate the analytes. Desorbed analytes are then available for their quantification depending upon the availability of the technique and its sensitivity. Graphite furnace atomic absorption spectrometry and neutron activation analysis techniques have been used for their final determination during this work. Most of the analytes found were in the ng g −1 range. Depending on the blank values, the reproducibility of the overall procedure is 2–10%. Separation of the matrix and recovery of the analytes were essentially complete as confirmed by standard addition of the analytes to the matrix and also by tracer studies.

Preconcentration of natural protactinium (231Pa) from monazite on Dowex 1X8 and subsequent determination by gamma-spectrometry

A simple and efficient method has been developed to preconcentrate natural protactinium from large quantity of monazite (5–10 g) and thorium concentrates (5–100 g), obtained from thorium plant stream on Dowex 1X8 in acid medium. Gamma-spectrometry, a powerful determination technique, has been used for quantitative determination of protactinium and uranium. Various parameters like sample preparation, optimization of the resin and sample size for 231Pa recovery, 231Pa/235U ratio have been studied in detail and are discussed.