Date

2016

Author

Bora, Selin

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Atom traps such as slotted quartz tube, quartz plate and tungsten coil have been used in atomic spectrometry in order to preconcentrate analyte hydrides and then detection was done by atomic absorption or fluorescence spectrometry. In this study, tungsten coil atom trap was used for the first time with plasma spectrometry. A novel method, which is called Hydride Generation Tungsten Trap Inductively Coupled Plasma Mass Spectrometry (HG-W-Trap-ICPMS), was developed in the first part of this study. Then as a second part, multi-element determination was performed by the proposed method. This novel method was developed step by step and using only Bismuth at the beginning. HG and then W-coil as a trap was coupled to ICPMS. Flow injection system was used in both nebulization and HG parts. For HG, volatile analyte species were transported from a U-tube type gas-liquid separator (GLS) to plasma. HG system was connected directly to the inlet of torch without any spray chamber and nebulizer system. W-trap was located between the plasma torch inlet and the GLS outlet. 106 mL/min H2 was passed through the atom trap to protect W-coil from oxidation. Both presence of H2 and air in the system disturb the plasma seriously. In order to sustain the plasma stability 125 mL/min make-up Ar was introduced to the system through inlet of trap tube. Hydride species were collected on W-trap at an optimized temperature and then revolatilized by heating the coil to a higher temperature. Transient signal with a halfwidth less than 0.5 s was obtained. Effect of dwell time and smoothing were also studied in this study. Dwell time was set to 10 ms for all parts and smoothing was not applied. After HG-W-Trap-ICPMS method was developed for only Bi, multi-element study for simultaneous determination of Bi and Tellurium in their mixture was performed successfully. For comparison, studies were also done by Te alone. In addition, effect of three different coatings, which were iridium, platinum and rhodium, were evaluated for each element. Sensitivities using nebulization, HG and HG-W-Trap were compared for Bi and Te determinations by ICPMS. When slopes of calibration plots are considered, as compared to nebulization, HG-W-Trap signals were 1255 and 106 times more sensitive for 209Bi and 130Te, respectively. For 1.0 min collection period, LOD values were found to be 2.7 ng/L for Bi with Ir-coated W-coil and 6.0 ng/L for Te with Pt-coated W-coil. Trapping efficiencies of Bi and Te were calculated as 40% and 15%, respectively. In simultaneous determination of these two elements slopes of the calibration graphs were found very close to that of single mass study for each element. Pt-coated W-coil was used for Bi and Te mixture study. Accuracies of the methods were checked by using the “NIST 1643e Trace Elements in Water” and “NIST 1643f Trace Elements in Water” standard reference materials. Determination of three elements simultaneously by HG-W-Trap-ICPMS method was also feasible. Antimony and selenium were used separately as a third element besides Bi and Te. Three masses study was performed by using the Pt-coated W-coil.

Subject Keywords

Bismuth., Tellurium., Selenium., Antimony., Mass spectrometry.

URI

http://etd.lib.metu.edu.tr/upload/12619832/index.pdf
https://hdl.handle.net/11511/25556

Collections

Graduate School of Natural and Applied Sciences, Thesis