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RECEIVED for review May 31, 1983. Accepted October 3, 1983. Partial support for this work was provided by an NIMH Neurosciences Progam-Prbject Grant (MH 23861) and an ONR Selected Research Opportunity Award (SRO001:N00014-79-C-0796).
Determination of Microgram Amounts of Selenium and Tellurium in Copper-Base Alloys by Atomic Absorption Spectrometry Michael Bedrossian
Armco, Inc., Research and Technology, 703 Curtis Street, Middletown, Ohio 45043 Selenium and tellurium are found in various sulfide ores and they are produced as a byproduct of metal refineries. Both selenium and tellurium are used in the refining of copper, in the manufacture of rubber, and in the electronics industry. Lately, selenium and tellurium have had important applications in the manufacture of steel and various alloys. Since certain properties of metals and alloys depend on the presence of selenium and tellurium, it is desirable to have a reliable analytical method for determining selenium and tellurium in coppebbase alloys below 100 ppm. An accurate method €or the determination of less than 50 ppm of tellurium in steels has been developed by using a solvent extraction procedure (1). Laboratory tests indicate that this procedure, with minor modifications, also is applicable to the determination of selenium and tellurium in nickel-base alloys. However, its application to copper-base alloys is limited. The most sensitive hydride evolution electrothermal atomic absorption spectrometric techniques are not reliable (2). In addition, the method is subject to serious interferences ( 3 , 4 ) . Tsukahara and Yamamoto (5) described the determination of tellurium in copper, lead, and selenium by flame atomic absorption. Albright e t al. (6) used X-ray to determine selenium in copper-, nickel-, and iron-base alloys. After reduction to their elemental forms, iodide complexes of both selenium and tellurium can be extracted simultaneously from copper-base alloys by the use of trioctylphosphine oxide-methyl isobutyl ketone and then determined by flame atomic absorption. This present method is highly sensitive and allows the determination of 0.0002% selenium or tellurium. EXPERIMENTAL SECTION Apparatus. A Perkin-Elmer Model 5000 atomic absorption spectrophotometer, equipped with an air-acetylene, single-slot burner head and Westinghouse electrodelessdischarge lamps were used. Reagents. All chemicals used were ACS certified reagent grade quality. Standard selenium solution of lo00 mg/mL and 5tandai.d tellurium solution of 100 mg/mL were prepared from the pure metals. Working solutions of 25 ,ug/mL for both selenium and
tellurium were prepared monthly by appropriate dilution of the stock solutions in 10% SCl acid. Trioctylphosphine oxide-methyl isobutyl ketone (TOPO-MIBK) solution ( 5 % ) was prepared by dissolvihg 12.5 g of TOP0 in MIBK in a 250-mL volumetric flask. Procedure. A 2.0-g sample size was used for the determination of trace levels of selenium and tellurium (
