Date

2014

Author

Özdemir, Erhan

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Determination of indium is important due to its growing importance in semiconductor industry and health concerns in occupational area. Due to extremely low abundance of indium in the earth crust, very sensitive and accurate methods are needed for its determination. Vapour generation atomic absorption spectrometry is a fast and economical technique for determination of conventional hydride generation elements such as As, Bi, Ge, Pb, Sb, Se, Sn, Te. However, there are very limited number of studies conducted for determination of indium by this method. Continuous flow vapour generation system was set and parameters were optimized. 2.0 mol/L HCl was used to acidify the sample solution and 6.0% NaBH4 was used for reduction of analyte to produce volatile species of indium. High memory effect, unstable nature of volatile species, unstable atomizer conditions were the problems affecting system performance. vi To solve problems faced in continuous flow vapour generation system, a new design of flow injection vapour generation system was used. In this system, reaction coil was removed from conventional hydride generation systems in order to separate and transport volatile species rapidly. Moreover, this system was combined with a quartz atom trap to increase sensitivity. Quartz trap is based on consumption of hydrogen produced in reaction between carrier acid and reducing agent, with introduction of oxygen gas into the system. In the absence of hydrogen, atomization of volatile indium species is not realized and species are trapped on the surface of quartz tube atomizer. After optimizations, LOD and %RSD values were calculated as 41 μg/L and 4.9, respectively according to peak heights. By removing parts of the system after saturation with 10.0 mg/L indium solution, sources of high memory problem of the system were investigated. It was concluded that adsorption on the GLS is the main source of memory effect. Vapour generation efficiency was also investigated throughout this study. Waste solutions were picked up and analyzed in ETAAS instrument. It was concluded that vapour generation efficiency for indium was 10.5%. Nature of volatile indium species was investigated. It was observed that indium volatile species can pass through 0.2 μm pore sized filter as it is in the case for stibine volatile species. Photochemical vapour generation system was also designed and tested for indium. No achievement was gained in generation of volatile species using UV radiation and organic acid. Waste solutions were collected and analyzed in ICPOES to conclude that no indium volatile species were generated.

Subject Keywords

Indium., Quartz., Atomic absorption spectroscopy., Vapor generation.

URI

http://etd.lib.metu.edu.tr/upload/12616766/index.pdf
https://hdl.handle.net/11511/23266

Collections

Graduate School of Natural and Applied Sciences, Thesis