FAAS testing one's metal: Steel analysis
- Published: Feb 15, 2017
- Author: David Bradley
- Channels: Atomic
Researchers in Japan have used a new flame atomic absorption spectrometer (FAAS) system, comprising a bright xenon lamp as the primary radiation source and a high-resolution Echelle monochromator, to study several 3d transition metal elements known to potentially be present in steel. The team's simultaneous internal standard FAAS method measures several absorption lines at a wavelength width of approximately 0.3 nanometres at the same time. This, the researchers, suggest allows them to obtain an estimate of the absorbances of an analytical line and also of an internal standard line simultaneously.
Widely used, narrow focus
FAAS has been used widely for the analysis of metals in solution samples. Various separation steps and preconcentration sequences have been reported over several years in the scientific literature. For the steel industry, it is vital to have straightforward, precise and accurate methods for quantifying trace elements and impurities given that the presence of such elements can strongly affect the bulk, strength, corrosion resistance and other properties. FAAS has the ability to detect trace metals that are present at lower concentrations than parts per million using relatively inexpensive equipment that is also easy to maintain and has low running costs. However, it has a narrow dynamic range of acceptable concentration when compared to inductively coupled plasma atomic emission spectroscopy (ICP-AES). Moreover, it is usual that only a single element can be quantified in a given FAAS experiment.
Now, Yusuke Toya, Toshiko Itagaki, and Kazuaki Wagatsuma of the Institute for Materials Research at Tohoku University, in Sendai, Japan, explain that in selecting an internal standard element for the determination of titanium, iron, and nickel, they found that elements in the platinum group, in other words, ruthenium, rhodium, and palladium were the most suitable. They point out that variation in aspirated amounts of sample solution coupled with a short-period drift in the primary light source would best be compensated and so reduced with this choice.
They carried out tests with typical metal couples: titanium and palladium, nickel and rhodium, and iron and ruthenium. Moreover optimal repeatability of the tests was seen when a nitrous oxide and acetylene flame was used rather than air and acetylene. This latter effect is due to decomposition processes in the high-temperature flame and differences in thermodynamic stability of the oxides formed in the experiment. Tests on a real-world steel sample confirm the better analytical precision of this FAAS technique the team reports in the journal Analytical Sciences.
Anal Sci 2017, 33, 217-222: "Application of Internal Standard Method for Several 3d-Transition Metallic Elements in Flame Atomic Absorption Spectrometry Using a Multi-wavelength High-resolution Spectrometer"
Article by David Bradley
The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.
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