Determination of trace oxygen in high-purity copper by inert gas fusion-infrared absorption method
CAO Fei-fei1,2, ZHOU Tao*2, ZHANG Dong-xiang1
1.Beijing Institute of Technology , School of Chemical Engineering and Environment, Beijing 100081,China; 2.National Institute of Metrology , Beijing 100013,China
Abstract：In order to reduce the blank of oxygen, an analysis method for the accurate determination of trace oxygen in high-purity copper by inert gas fusion-infrared absorption was established without the addition of flux. The results indicated that the optimal experimental conditions were as follows: 0.8 g of sample was determined in standard graphite crucible; the purge time was 35 s; the evacuation time was 25 s; the evacuation cycle was twice; the evacuation power was 4 500 W; the analytical power was 4 000 W. The standard deviation of blank was 0.027 μg/g, and the quantitative limit of oxygen was reduced to 0.27 μg/g. 10-30 μg of high-purity iron oxide was accurately weighed in tin capsule for the correction of instrument. The correction coefficient was 1.034, solving the problem that there was no standard certified reference material. The actual high-purity copper samples were determined by the proposed method. The found oxygen mass fraction in copper was 2.43 μg/g. The relative standard deviation (RSD) was less than 7.7%. During the evaluation of measurement uncertainty, some influencing factors were considered including the measurement repeatability of calibration sample, the purity of iron oxide reagent, the measurement repeatability of sample and the blank. The uncertainty of oxygen mass fraction in copper was 0.33 μg/g (k=2). The high-purity iron oxide was added into high-purity copper oxide for the recovery test, with the recoveries between 100% and 105%.
Ryo Inoue, Hideaki Suito. Determination of oxygen in iron-aluminum alloy by inner gas fusion-infrared absorptiometry [J]. Materials Transations, JIM, 1991, 32(12):1164-1169.
[7]
Zhou T, Richter S, Matschat R, et al . Determination of the total purity of a high-purity silver material to be used as a primary standard for element determination [J]. Accreditation and Quality Assurance, 2013, 18(4):341-349.
