James Jaganathan

Separation of Intrinsic and extrinsic Optical-Absorption in a Fluoride Glass

The contribution of impurity ions to the total optical absorption of a heavy metal fluoride glass has been determined at 532 and 1064 nm. Four ZrF4‐BaF2‐LaF3‐AlF3‐NaF glasses were prepared from various purity raw materials. The absorption coefficients of these glasses range from 0.92 to 45.4×10−4 cm−1 at 1064 nm and from 7.43 to 11.1×10−4 cm−1 at 532 nm as determined by laser calorimetry. The concentrations of Fe, Ni,Cu, and Co ions in each glass were determined by graphite furnace atomic absorption spectroscopy. These two measurements enable the absorption, due to transition metal ions to be differentiated from the intrinsic absorption of the glass. At 1064 nm, the absorption coefficient of these glasses is controlled entirely by the transition metal ion content. However, at 532 nm, the absorption by the transition metal ions accounts for 4–42% of the total absorption depending on impurity concentration. The intrinsic absorption of this fluoride glass calculated from these data at 532 nm is (7.69±0.99)×10−4 cm−1.

Determination of iron, cobalt, nickel, and copper in hafnium fluoride by GF-AAS

This paper describes an analytical method for the quantitation of iron, cobalt, nickel, and copper at trace levels with graphite furnace-atomic absorption spectrometry (GF-AAS) without the use of any matrix modifier or preconcentration techniques. A solution of HfF4 (10%, w/v) in HF (24%) was used for this study. The detection limits for iron, cobalt, nickel, and copper were found to be 3, 1, 3, and 2 ppb, respectively. The average precision of measurements (% RSD) for all the elements was <10%.

Quantitative determination of nickel and copper in zirconium fluoride using graphite furnace atomic absorption spectrophotometry

Abstract A graphite furnace atomic absorption spectrophotometer (GFAAS) with Zeeman-effect background correction has been used for the determination of nickel and copper at very low level concentrations in a 30% ( w v ) solution of zirconium fluoride. Using palladium nitrate and nitric acid as matrix modifiers, the detection limits for nickel and copper were determined to be 6.3 and 3.2 ng/g, respectively. A specially made graphite platform was used for this study because it was found to withstand the drastic conditions of analysis for a longer period of time than a graphite tube alone. The technique has been validated by recovery studies on spiked samples and by comparing the slopes of standard addition and calibration curves. The precision of the procedure was significant and the relative standard deviation Was

Detection of trace levels of mercury in aqueous systems via a fiber optic probe

Currently there is a great deal of interest in the development and use of fiber optic chemical sensors for characterization of contaminated waste sites. Development of remote, in-situ sensors for rapid determination of the presence, and concentration of hazardous materials will significantly reduce site remediation costs. The state-of-the-art technology for assessing site contamination is the cone penetrometer system. This system consists of a 2-1/2 ton truck, a hydraulic ram, and a steel tube. The steel tube, which is generally 1-3/4 inches OD and 1 inch ID, has a sharp tip on one end. To begin site characterization the penetrometer tube is placed into the hydraulic ram then the tube is pushed into the ground. Sensors are mounted in the penetrometer tube to measure contaminants in the surrounding soil and ground water. This system has several distinct advantages over conventional drilling techniques. Additionally, site characterization can be performed much quicker than standard drilling techniques. Fiber optic chemical sensors are readily applicable towards use in cone penetrometer systems since they are small in size and can report real time, in-situ results. Some fiber optic chemical sensors have been deployed and tested in the cone penetrometer system.

Graphite furnace atomic absorption spectrometric determination of iron, cobalt, nickel, and copper at parts-per-billion level in high-purity lanthanum fluoride

This paper describes an analytical method for the quantitation of iron, cobalt, nickel, and copper in lanthanum fluoride at trace levels with graphite furnace atomic absorption spectrometry (GFAAS) without using any matrix modifier. These metals were preconcentrated in HNO3 and analyzed directly. The detection limits for iron, cobalt, nickel, and copper were found to be 3, 1, 2, and 2 ppb, respectively. The average precision of measurements (°/o RSD) for all the elements was <10%.

Determination of trace levels of iron and cobalt in zirconium fluoride using graphite furnace atomic absorption spectrometry

In this paper we describe the analysis of high solid content solutions of zirconium fluoride for low ng/g concentrations of transition elements (Fe and Co) using Zeeman corrected GFAAS and the matrix modifiers, palladium nitrate and nitric acid

Preparation of high purity lanthanum compounds for use in fluoride optical fibers

Abstract The preparation of ultra-pure lanthanum nitrate by coprecipitation is described. Preparation of high purity lanthanum carbonate from the pure nitrate is also described. Hydrofluorinationof pure lanthanum carbonate produces high purity lanthanum fluoride used in the preparation of heavy metal fluoride glasses.

Determination of iron, cobalt, nickel and copper in a zirconium-based glass by electrothermal atomic absorption spectrometry

By dissolving a zirconium-based fluoride glass in a solution of zirconium oxychloride, ZrOCl2·8H2O, the direct determination of Fe, Co, Ni and Cu was achieved by electrothermal atomic absorption spectrometry. The accuracy of results obtained from solution analysis was confirmed using a preconcentration method carried out independently. The average precision of measurements (relative standard deviation) for all the elements was <10% and the methodological detection limits for Fe, Co, Ni and Cu, based on the preconcentration technique, were 0.05, 0.04, 0.1 and 0.04 ng g–1, respectively.