Antimony is a toxic element which is mostly found in two oxidation states (III and V) in environmental, biological and geological samples. Antimony may form various inorganic and organic compounds that exhibit differences in analytical behavior, toxicity and mobility / inorganic compounds of antimony are more toxic than organic forms and toxicity of Sb(III) has been shown to be 10 times higher than that of Sb(V). Therefore selective determination of Sb(III) and Sb(V) is required in environmental and biological samples. Hydride generation atomic absorption spectrometry is a sensitive, fast and economical technique for the determination of antimony at trace level. A possible non-chromatographic method for antimony speciation is hydride generation atomic absorption spectrometry that is based on the relatively slow kinetics of hydride formation from Sb(V). In this study, continuous flow hydride generation method for the determination of antimony was developed and hydride generation conditions were optimized. Analyte solution was prepared in 0.050 mol/L HCl and 1.2% (w/v) NaBH4 stabilized in 0.30% (w/v) NaOH was used as a reductant solution. Inorganic antimony speciation conditions were determined by continuous flow HGAAS system. For the pre-reduction of Sb(V) to Sb(III), 8.0% (w/v) potassium iodide (KI) and 0.10% (w/v) ascorbic acid were used. Further speciation study was also carried out using Ir coated W-coil Atom Trap Hydride Generation Atomic Absorption Spectrometry. Tungsten coil atom trap was used to enhance the sensitivity. Tungsten coil surface was treated with Ir and totally 250 &amp / #956 / g 1000 mg/L Ir stock solution was used for coating of tungsten coil. LOD and LOQ values were calculated as 152 pg/mL and 508 pg/mL according to 120 seconds trapping. 128 and 37 fold enhancement were obtained for 120 seconds collection with respect to W-coil-ETAAS and ETAAS, respectively.

ABSTRACT SOIL AND WATER ANALYSIS TECHNIQUES FOR AGRICULTURAL PRODUCTION Maral, Nuh M. Sc., Department of Chemistry Supervisor: Prof. Dr. G. inci G&ouml / kmen May 2010, 108 pages In Turkey, usage of increasing amounts of fertilizers and pesticides by some unconscious farmers cause soil pollution and soil infertility for the crop production. Usage of water in excessive amounts and/or in poor quality for irrigation creates problems during the plant production. So in this study, soil and water samples were analyzed by using simple and reliable techniques for the soil and water quality in laboratories of METU and Soil Fertilizer and Water Resources Central Research Institute Laboratory in Ankara. The soil and water samples were collected using the standard techniques from Ankara, Bolu, &Ccedil / orum and Kirikkale. According to the soil test results, the textures of the soil samples are found as loam and clay loam. The total salt content of the soil samples are between 0.033 &ndash / 0.063 % (w/w), meaning they are low salinity soils (total salt less than 0.15 % w/w). The pH of the soil samples are between 7.86&ndash / 8.15, they are slightly alkaline. The phosphorus concentrations of soil samples are in a range 4.95 to 35.45 P2O5 kg/da. Some of the soil samples have too high phosphorus content (greater than 12 P2O5 kg/da). The potassium content of soil samples are found between 141&ndash / 286 K2O kg/da, so the soil is efficient for crop production. Lime content of the soil samples is between 1.04&ndash / 2.67 % (w/w) CaCO3. It means all of the soil samples are calcareous but it is not too high for the agricultural production. Organic matter content of soil samples are found between 0.83&ndash / 2.04 % (w/w). This means the soils are limited in their organic matter content for the crop production. Analysis of 22 water samples yielded EC values between 0.384 &ndash / 1.875 dS/m. Water samples have moderate to high-salinity (if EC values between 0.205 and 2.250 dS/m), yet these can be used for the irrigation of the crops. pH values of water samples are found between 7.18-8.10, meaning that they are slightly alkaline. Bicarbonate concentrations of 19 of the water samples are greater than 200 mg/L. These waters may not be suitable for irrigation of ornamental plants. All of the water samples, except water samples from G&ouml / lbaSi, have sodium absorption ratio (SAR) values between 1 and 9. Water samples with low SAR values, except water samples from G&ouml / lbaSi, can be used for irrigation of almost all soils with little danger of developing harmful levels of sodium. The Residual Sodium Carbonate (RSC) values of water samples Ankara G&ouml / lbaSi and Sincan-1 are greater than 2.50 meq/L and these water samples are not suitable for the irrigation. RSC values of Etimesgut, Sincan-2 and Kazan water samples are positive and lower than the value 2.00 meq /L. All the other water samples have negative RSC values so they are the safe to use for irrigation. It has been observed that development of practical field analysis techniques for all soil and water quality parameters may be possible with exception of micronutrient determination. For determining soil and water quality parameters in the rural areas there is a need to establish a small laboratory with necessary equipment and apparatus and training one or two farmers. With the experience gained in this study, some of these techniques may be adapted to the rural field applications, so soil and water may be tested by the farmers for better yields.

ABSTRACT ARSENIC SPECIATION IN FISH BY HPLC-ICP-MS &Ouml / ZCAN, Sefika Eroglu M.S., Department of Chemistry Supervisor: Prof. Dr. O. Yavuz ATAMAN September 2010, 103 pages Arsenic speciation in fish samples on the market was performed using isocratic elution with cation exchange column high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Total As concentrations were found by ICP-MS using samples digested by nitric acid-hydrogen peroxide solution using microwave oven digestion / the results were in the range of 1.15-12.6 &micro / g/g. Separation of organic arsenicals, namely arsenobetaine (AB), dimethylarsinic acid (DMA) and monomethylarsonic acid (MA), have been achieved in 12 minutes. Freeze-dried samples were extracted by deionized water with a shaker system / the concentrations of AB and DMA in the extract was then determined using HPLC-ICP-MS. The accuracy of the method for determining AB concentration was confirmed using certified reference material (CRM), DOLT 4 (dog fish liver) / for this CRM only preliminary data are available for AB. The arsenic compounds in 6 fish muscle samples were investigated. The predominant arsenic compound found in extracts was AB / the concentrations were in the range of 0.86-12.0 &micro / g/g. DMA concentration was 0.40&plusmn / 0.03 &micro / g/g in one of the samples / in the others it was below the limit of quantation (0.21 &micro / g/g).

In biomedical applications, magnetic nanoparticles have been used as they offer attractive possibilities. First, they have controllable sizes ranging from a few nanometers up to tens of nanometers and second, the nanoparticles are magnetic and magnetic fields can penetrate into human tissue which means that they can be manipulated by an external magnetic field gradient. In this study, Fe

ABSTRACT SENSITIVE AND QUANTITATIVE DETERMINATION OF CYSTEINE BY SURFACE ENHANCED RAMAN SPECTROMETRY BASED ON THEIR INDUCED AGGREGATES OF GOLD AND SILVER NANOSTRUCTURES Y&uuml / ksel, Recep M.Sc., Department of Chemistry Supervisor: Prof. Dr. M&uuml / rvet Volkan September 2011, 76 pages The synthesis of noble metal nanostructures are an active research area and controlling the shape and the size is a challenging task. In this study, nanostructures with different morphologies were prepared using wet chemical synthesis techniques in the aqueous solutions. Gold and silver nanospheres were produced by reducing and capping agent trisodium citrate. Gold nanorods were synthesized by chemical reduction of HAuCl4 by ascorbic acid in the presence of cetyltrimethylammonium bromide (CTAB), AgNO3, and gold nanoseeds (in 1.5 nm diameter) and gold silver core shell nanorods were prepared by addition of silver atoms on the surface of gold nanorods in the presence of CTAB. Parameters that were critical to obtain homogeneous nanostructures were optimized. The characterization of the nanoparticles was performed by UV-VIS spectrometry, High Resolution - Transition Electron Microscopy (HR-TEM), Field Emission - Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDX). Besides, their electromagnetic enhancement properties were demonstrated through SERS measurement of cysteine. Self-assembly or assisted assembly of nanorods or nanospheres into organized arrays allows the realization of their collective properties that arise from the coupling of the optical and electronic properties of the neighbouring individual nanoparticles. In this study cysteine molecule was used as a linker molecule. The controlled addition of cysteine into the gold nanorod solution resulted in their preferential binding to the two ends of the gold nanorods and the formation of gold nanochains. In the usage of gold nanospheres on the other hand, cooperative hydrogen bonding of the cysteine molecules, resulted in the formation of gold nanoclusters. The assembly formation was demonstrated by UV&ndash / vis spectrometry and FE-SEM. Cysteine is a thiol group containing amino acid and deficiency of cysteine results in serious health problems. Therefore, determination of cysteine is an important issue. Herein we report two strategies for the quantitative determination of micromolar concentrations of cysteine by exploiting the interplasmon coupling in Au nanoparticles. One of them is a recently published colorimetric method and the other is a novel SERS method.

Determination of thallium is important due to its toxic effects on the environment and human health. Extremely low abundance of thallium in earth crust requires very sensitive and accurate methods for determination of this element. Although volatile compound generation is a sensitive, fast and economical method, thallium determination by this method has not been sufficiently investigated in literature, because of the fact that the formation of volatile forms of this element is a difficult task. A continuous flow volatile compound generation system was developed and parameters that affect the analytical signal were optimized. Sample solutions were acidified with 0.5 mol/L HNO3 and prepared in 0.0005% (v/v) rhodamine B and 1.0 mg/L Pd while 0.5% (m/v) NaBH4 stabilized in 0.5% (m/v) NaOH was used as reductant. Fast decomposition and unstability of thallium volatile species affected system performance negatively. Flow injection volatile compound generation studies were carried out with a special system. After optimizations, LOD and LOQ values were calculated as 12 ng/mL and 40 ng/mL according to peak height values in HNO3 medium. Similarly, in HCl medium LOD and LOQ values were calculated as 14 ng/mL and 45 ng/mL. Addition of Te and Pd to the sample solution containing co-enhancement reagent rhodamine B improved volatile compound generation efficiency in peak height by 3.6 and 9.3, respectively. Type of the acid used was affected peak heights and peak shapes of Tl+ and Tl3+ volatile species and HNO3 medium gave better results. By changing the location of introduction for Ar gas, the sources of memory effects and reasons of peak broadening were investigated. Most of the memory effects were coming from the gas-liquid separator (GLS) or before the GLS, as well as T-tube atomizer. Nature and behavior of Tl volatile species were also investigated and it was found that Tl and also Pd were generated in the form of nanoparticles. Transmission electron microscopic (TEM) measurements prove the presence of Tl nanoparticles in the analyte species transported to the atomizer by the effect of carrier Ar gas.

In this work, wet deposition samples were collected at Middle East Technical University campus, Ankara, between December 2000 and May 2002. Snow samples were collected from 50 grids in January, 2001 in Ankara to investigate dry deposition of PAHs. The collected samples were preconcentrated by Solid Phase Extraction and ultrasonic extraction tecniques. Extraction methodologies were improved prior to analysis of samples. Extracted samples were analyzed by Gas Chromotography-Mass Spectrometry for 14 Polycyclic Aromatic Hydrocarbons. Selected Ion Monitoring mode was used throughout the analysis. Phenanthrene, fluoranthene, pyrene and benzo (b+k) fluoranthene were found to be dominant PAHs in wet deposition samples. Seasonal variation of PAHs were observed having higher concentrations in winter period. Meterological parameters were also examined together with PAH concentrations. Contribution of PAHs coming from North East and South West direction were found to be dominant. Wet deposition fluxes were calculated and compared with other urban sites. Wet deposition fluxes are lower than industrial sites and comparable with urban sites in Europe. PAH ratios and factor analysis results demostrated combustion and traffic emissions are major sources of pollutants in the city. Dry deposition of PAHs were invesigated using snow as a natural collecting surface. Dry deposition fluxes calculated using snow surface are compareble with other similar sites. Dry deposition pollution maps of PAHs were drawn by MapInfo software and it was observed that the major pollution regions are the localities where low income families live and low quality coal used for heating purpose. Ratio calculations showed that the central parts of the city is mostly affected from traffic emissions while coal emissions are dominating at the other parts of the city. Factor analysis applied to data set and 6 factors distinquished as coal, soil, traffic, oil combustion, mixed combustion and road dust.

ABSTRACT ELECTROCHEMICAL HYDRIDE GENERATION AND ATOM TRAPPING ATOMIC ABSORPTION SPECTROMETRY FOR DETERMINATION OF ANTIMONY Menemenlioglu, ipek M.S., Department of Chemistry Supervisor: Prof. Dr. O. Yavuz Ataman June 2004, 82 pages Electrochemical hydride generation is a suitable alternative to common hydride generation by NaBH4 which is widely used for the detection of volatile elements such as As, Se, Sb, Sn, Bi, Ge, Te and Pb. In this study, a thin-layer flow through electrochemical cell was designed. Lead and platinum foils were employed as cathode and anode materials, respectively, for the generation of antimony hydride. Argon was used as the carrier gas. The inlet arm of the conventional quartz tube atomizer was used for on-line preconcentration of generated hydrides. A portion of the inlet arm was heated externally to the collection temperature for trapping the analyte species which were generated electrochemically. For the revolatilization of the trapped species, the trap was further heated to the revolatilization temperature and hydrogen gas was introduced into the system 10 seconds afterwards. The experimental operation conditions for electrochemical hydride generation which include the acidities and flow rates of catholyte and anolyte solutions, carrier gas flow rate and the applied electric current, were optimized. For trapping, collection and revolatilization temperatures and hydrogen flow rates were optimized. Analyses of standard reference materials were performed to check the accuracy of the proposed method. 3&amp / #963 / limit of detections were found as 1.03 ng ml-1 and 0.053 ng ml-1 with and without employing the trap, respectively. The trap has provided 20 fold sensitivity improvement.

Trace amounts of germanium is determined by flame atomic absorption spectrometry by utilizing the vaporization of germanium tetrachloride. Using a continuous flow reactor, sample solution is mixed with concentrated hydrochloric acid and heated to 80&ordm / C to form volatile germanium tetrachloride which can be subsequently sent to N2O-C2H2 flame AAS. The necessary conditions for the volatilization of germanium tetrachloride are investigated in detail and the applicability of the method for the determination of trace amounts of germanium in real samples and standard reference materials are presented. Detection limit of the method, based on 3s, was 0.034 ng mL-1 using a sample of 1 mL. The precision was 0.3 %, expressed as the relative standard deviation for a germanium concentration of 1 ng mL-1. Owing to the high selectivity of the proposed method, no interference effect was observed.

Lactic acid is a fermentation-derived organic acid used in a wide range of industries, such as food processing and pharmaceuticals. Its market is expected to expand due to the worldwide concern for the environment, as it is an essential feedstock for biodegradable polymers. However, fermentation product is a very dilute, multicomponent aqueous solution. Subsequent separation, purification and concentration of organic acids is difficult because of high affinity of the acids for water. Reactive extraction is a viable alternative to classical separation techniques. Amine extractants dissolved in organic diluents are suitable agents with reasonable ranges of viscosity and density of the solvent phase. The product is obtained in an organic phase after reactive extraction. The aim of this study is to obtain equilibrium data of back extraction of lactic acid into appropriate aqueous solutions from the organic phase. Aqueous solutions of NaCl, NaOH, Na2SO4, NaNO3 and Na2CO3 were examined as back extractant in various initial concentrations (0.005 &ndash / 3 M). The organic phase consists of tri-n-octylmethylammonium lactate (TOMA(La)) dissolved in either oleyl alcohol or octanol with initial concentrations between 0.1 and 0.3 M. According to results of the experiments, the level of back extraction generally increased with increasing initial salt concentration in aqueous phase and decreased with increasing initial TOMA(La) concentration in organic phase. For all salts investigated, considerable levels of back extraction were obtained. NaOH was considered as the most suitable back extractant among the salts investigated since it exhibits higher distribution coefficients, regenerates tri-n-octylmethylammonium hydroxide (TOMAOH) in the organic phase and has no adverse effect on fermentation medium when forward and backward extraction steps are coupled with the fermentation. The effect of diluent type of TOMA(La) was also investigated during the experiments and it was concluded that octanol is a better diluent since it gives higher equilibrium distribution coefficients in addition to its higher solvating power and lower viscosity. The present work is a part of a comprehensive research program aiming to collect data and develop knowledge for the design of an industrial reactive extraction process coupling forward and backward extraction of lactic acid in a single unit and integrating fermentation and product separation. The kinetic parameters should be obtained as the next step for the design of such a process.