ABSTRACT PREPARATION AND CHARACTERIZATION OF SILVER SERS NANOTAGS Kibar, Seda M.S., Department of Chemistry Supervisor: Prof. Dr. M&uuml / rvet Volkan December 2010, 88 pages Tags are materials used for labeling substances and so make possible the qualitative and quantitative analysis both in macroscopic and microscopic world. Nowadays, surface enhanced Raman spectroscopy became the favored one among the optical based-tag detection systems. Progress in surface enhanced Raman detection and imaging technologies depends on the availability of Raman labels with strong light scattering characteristics. In this study various SERS nanotags were prepared. An ideal SERS nanotag consists of three parts, core nanoparticle for enhancement, Raman active molecule for signature and a shell for protection and further functionalization. As a core material, silver nanoparticles were prepared using the chemical reduction method with sodium citrate as reductant. SERS enhancement provided by Ag particles prepared was examined. For colloidal stabilization and further surface modifications, silica with a controlled thickness was deposited on Ag nanoparticles. Three single-dye doped nanotags, Ag-BCB@SiO2 Ag-CFV@SiO2 and Ag-CV@SiO2 were prepared using positively charged dyes, brilliant cresyl blue (BCB), cresyl fast violet (CFV) and cresyl violet (CV). The effects of silica thickness and dye concentration in the reaction medium were examined. Stability of prepared nanotags and repeatability of the method were investigated. Multi-dye doped nanotags were prepared using BCB and CFV solutions mixed at various concentration ratios. Resulting Raman spectra Ag-BCB-CFV@SiO2 nanotags successfully exhibited characteristic peaks of each dye with a good resolution. In addition, the molar ratio between dyes BCB and CFV was reflected on the related spectra. A linear correlation was observed between the molar ratio of the dyes and their Raman intensity ratio.

In this study, the Persistent Organic Pollutants (POPs) specifically / 17 Organochlorine Pesticides (OCPs) and 19 Polycyclic Aromatic Hydrocarbons (PAHs) were evaluated in the sediment samples of Balikesir (Ikizcetepeler) Dam Lake. Sixteen sampling points were chosen for determination of concentrations of OCPs and PAHs After ultrasonic bath extraction of the sediment samples GC-MS was used as analytical tool. Extraction efficiencies changes from 63.8 to 87.4% depending on the type of the POPs. Average OCP concentration was found in the range of 3.33-379 &micro / g/kg a, average PAH concentration was found in the range of 3.28-32.9 &micro / g/kg. Pollution maps regarding OCP and PAH distributions were drawn and the correlation between these two pollutant types was investigated. The quality control (QC) and quality assurance tests were applied by the analysis of standard reference materials (SRMs), surrogate standards and analysis replicates.

The main aim of this study is to combine the sol-gel technology and renewable surface flow injection analysis (RS-FIA) techniques for iron speciation and determination. Thus the home-made FIA system, which consists of 2 syringe pumps and 3 multi-position selection valves, is modified with two flow cells (magnetic cell and jet ring cell) in order to be suitable for renewable surface flow injection technique. All the computer programs used for flow injection analysis are modified to control the whole system automatically. Two different types of solid phase extraction materials are used for the speciation of iron in aqueous systems. Magnetic beads coated with primary amino groups are utilized for the determination of Fe (III). The magnetic bead reactor is created within the flowing stream by retaining the magnetic beads with a home-made electromagnet. The elution cycle for Fe (III) is done with 0.1 M EDTA solution and determined on-line by transferring to an atomic absorption spectrometer. The spent beads are collected off-line and regenerated. For the preconcentration of Fe (II), ferrozine doped sol-gel beads are prepared as reactive and disposable surfaces. These beads are handled by the system equipped with a jet ring cell which is connected on-line to a portable UV-VIS fiber optic spectrometer. Amino sol-gel and ferrozine-doped sol-gel beads are prepared using sol-gel technology and characterized by using surface techniques. Their performances in preconcentration and speciation of iron and the influence of different experimental parameters such as pH, the sequence of reagents, reactor lengths and reaction periods on the flow system are investigated. Renewable surface flow injection analysis is performed by either bead injection or sequential bead injection methods.

In this study, a reversed-phase high performance liquid chromatography (RP-HPLC) method has been developed to separate and determine Pt and Pd after formation of their chelates with N,N-diethyl-N&#039 / -benzoylthiourea (DEBT). With the aim of reducing the number of steps in treating the samples, the method developed does not require the elimination of excess chelating reagent before the analysis of metal chelates. The different physical and chemical parameters affecting separation were examined in details. The whole analysis was completed on a C18 column in 16 min at 280 nm, with the mobile phase of acetonitrile-methanol-water (80:10:10, v:v:v) containing 0.20 mol l-1 pH 5.0 acetate buffer at a flow rate of 0.8 ml min-1. Detection limits of the method, based on 3s, were found as 14.2 ug l-1 for Pd and 0.77 mg l-1 for Pt using a 20-ul sample loop. Reproducibility of the method for ten repeated measurements was found as 2.36 % for 0.60 mg l-1 Pd and 2.58 % for 10.0 mg l-1 Pt as % RSD. The proposed method is a rapid, simple and highly selective method for the simultaneous determination of Pt and Pd by HPLC without the need for any interference elimination process.