Date

2012

Author

Şimşek, Nail Engin

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Boron (B) is a rare element on Earth crust with a natural abundance of 0.001%. However, boron content of water and soils may be significantly high in the regions with rich boron reserves. In addition, extensive use of agrochemicals in soils as well as various natural processes increases the boron concentration in water. Despite B is an essential element for all living creatures, it may pose risks at high level exposures. World Health Organization (WHO) has recommended a daily intake of 1 to 13 mg B for adults. Turkey has almost 70% of world boron reserves principally in four regions: Kütahya, Emet; Balıkesir, Bigadiç; Eskişehir, Kırka and Bursa, Kemalpaşa. The boron content of water in these regions may go up to significant levels. Therefore, it is important to determine B in drinking water from these regions. Electrothermal atomic absorption spectrometry (ETAAS) is a relatively sensitive technique for determination of boron. However, the technique suffers from formation of molecular boron compounds. Therefore, use of chemical modifiers and pyrolytically coated graphite tubes modified with refractory carbide forming elements (Ta, W, Zr, Pd, Ru, Os) were utilized to develop a reliable and sensitive method. Based on optimization studies, Tantalum (Ta) coated tube and co-injection of 5.0 µL 0.01 mol/L Ca(NO3)2, 5.0 µL 0.05 mol/L citric acid together with 15.0 µL sample solution prepared in 1000 mg/L Mg(NO3)2 have been chosen as optimum conditions. Optimum temperatures for pyrolysis and atomization temperatures were determined as 1100 and 2700 °C, respectively. Under these conditions, a detection limit of 0.088 mg/L and a characteristic mass of 186 pg for 15.0 µL sample volume were obtained. The accuracy of the method was checked by EnviroMAT-Waste Water EU-L-1 CRM and NIST 1573a Tomato Leaves SRM analyses. Drinking water samples were collected from Balıkesir, Bigadiç and Kütahya, Emet and analyzed by the developed method. Samples were also analyzed by more sensitive techniques; ICP-OES and ICP-MS for a comparison study. The results are compatible with each other.

Subject Keywords

Boron compounds., Water, Atomic absorption spectroscopy.

URI

http://etd.lib.metu.edu.tr/upload/12614868/index.pdf
https://hdl.handle.net/11511/21853

Collections

Graduate School of Natural and Applied Sciences, Thesis