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: K&uuml / tahya, Emet / Balikesir, Bigadi&ccedil / Eskisehir, Kirka and Bursa, Kemalpasa. 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 &micro / L 0.01 mol/L Ca(NO3)2, 5.0 &micro / L 0.05 mol/L citric acid together with 15.0 &micro / L 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 &deg / C, respectively. Under these conditions, a detection limit of 0.088 mg/L and a characteristic mass of 186 pg for 15.0 &micro / L 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 Balikesir, Bigadi&ccedil / and K&uuml / tahya, 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.

Boron element plays an important role for our country since approximately 70% of the world&rsquo / s reserves are in Turkey. It is widely used in different areas of industry. Besides being vital for the plants, it is important also for human health. It has been shown that high boron exposure does not affect fertility negatively and also with an increasing boron exposure, risk of prostate and cervical cancers decreases. There are different opinions regarding health effects of boron. There are both positive and negative findings. Therefore, determination of boron in body fluids such as urine and blood is necessary to monitor exposed concentration level and its relation with diseases. Furthermore, these studies may contribute to define a reference value for safe maximum daily boron intake. In this study, a method previously developed by our research group was applied for the determination of boron in urine samples. Urine and blood samples were collected from human subjects living or working in different regions of Balikesir where boron reserves are located. While urine analysis was done by using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), due to lower concentrations of boron in blood, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used for blood analysis. A sensitive method was developed using ICP-MS. Samples were digested in microwave oven by applying optimized digestion procedures. Indium (In) and Beryllium (Be) internal standards were spiked into the urine and blood samples, respectively. A sample introduction system containing no glass or silica surfaces was used in ICP-MS to eliminate boron memory effect. Two isotopes of the boron, 10B and 11B, were monitored during the study. Space charge effect due to Na+ ion and carbon interference on B and Be signals was investigated in detail. Limit of Detection was 0.021 mg/L for ICP-OES and it was 2.2 &micro / g/L for ICP-MS. The accuracies of the methods were checked by using NIST 1573a Tomato Leaves and BCR Human Hair certified reference materials for urine and blood, respectively.

Made available in DSpace on 2015-05-14T13:21:18Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 5236156 bytes, checksum: bb419d4ddca1889deb0fe27fbd777c26 (MD5) Previous issue date: 2012-08-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work introduces the monosegmented flow-batch (MSFB) analysis concept. This system combines favourable characteristics of both flowbatch and the monosegmented analysers, allowing use of the flow-batch system for slow reaction kinetics without impairing sensitivity or sampling throughput. The MSFB was evaluated during spectrophotometric determination of boron in plant extracts, which is a method that involves a slow reaction between boron and azomethine-H. All standard solutions were prepared in-line, and all analytical processes completed by simply changing the operational parameters in the MSFB control software. The limit of detection was estimated at 0.008 mg L−1. The measurements could be performed at a rate of 120 samples per hour with satisfactory precision. The proposed MSFB was successfully applied to analyse 10 plant samples and the results are in agreement with the reference method at a 95% level of confidence. / Esse trabalho introduz o conceito fluxo-batelada monossegmentado (monosegmented flow-batch - MSFB). Esse sistema combina as características favoráveis do sistema fluxo-batelada (flow-batch analysis FBA) e do fluxo monossegmentado (monosegmented flow analysis MSFA), permitindo o uso do FBA em reações de cinética lenta sem prejuízo na sensibilidade ou na frequência de amostragem. O MSFB foi avaliado durante a determinação espectrofotométrica de boro em extrato de plantas, baseado no método que envolve a reação lenta entre o boro e a azometina-H. Todas as soluções padrão foram preparadas in-line e todos os processos analíticos foram realizados por simples mudanças nos parâmetros operacionais do software de controle do MSFB. O limite de detecção foi estimado em 0,008 mg L-1. As medidas foram executadas com frequência analítica de 120 amostras por hora, com precisão satisfatória. O MSFB foi aplicado com sucesso na análise de 10 amostras de extratos plantas e os resultados foram equivalentes aos obtidos pelo método de referência, ao nível de 95% de confiança estatística.