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Abstract The present work is concerned with Raman spectroscopy and some of its applications. The thesis comprises four main chapters in addition to an introduction and scope of investigation: Introduction: Raman spectra are acquired by irradiating a sample with a powerful laser source of visible or near-infrared monochromatic radiation. During irradiation, the spectrum of the scattered radiation is measured at some angle (often 90 deg) with a suitable spectrometer. At the very most, the intensities of Raman lines are 0.001 % of the intensity of the source; as a consequence, their detection and measurement are somewhat difficult. Surface enhanced Raman spectroscopy (SERS) involves obtaining Raman spectra in the usual way on samples that are adsorbed on the surface of colloidal metal particles (usually silver, gold, or copper) or on roughened surfaces of pieces of these metals. Raman lines of the adsorbed molecule are often enhanced by a factor of 103 to 106 times. Chapter I: It contains two parts, Part 1: SERS detection of certain dyes in sequential injection analysis. SERS technique was successfully combined with SIA with a full automated system using LabView software. In-situ photo-reduction of silver ions was developed to produce a SERS substrate. The whole setup was full computer controlled by using ATLAS software. The proposed method studied the enhancement effect of the photo-reduced SERS spot with the elimination of the memory effect that was produced in all the flowing systems. In order to test the success of the proposed method, two applications were carried out. The developed method was applied on certain dyes like Cu(PAR)2 complex, rhudamin6G and methylene blue. Different variables affecting the SERS intensity of Cu(PAR)2 complex, such as carrier’s concentrations, flow rate and the volume of the injected analyte were studied. A validation study of the developed method was performed. Under the optimal conditions, the calibration curve for the standard Cu(PAR)2 complex was constructed. The obtained calibration curve was linear in the range of 2.5-100 μg/ml with a good correlation coefficient (r= 0.9992). Limit of detection (LOD) and limit of quantitation (LOQ) were 0.7 and 2.0 μg/ml, respectively. It was found that; the method is precise and robust. Part 2: Combination of SERS and SIA for simultaneous determination of aspirin and vitamin C in bulk and in pharmaceutical dosage forms. The combination between SERS and SIA was applied for the quantitative determination of aspirin and vitamin C simultaneously in bulk and dosage forms. All variables affecting the SERS intensity of both studied drugs include; the carrier’s concentration, flow rate and the diluting solvents were studied. A validation study of the proposed method was performed. Under the optimal condition, calibration lines of the studied drugs were constructed. The obtained calibrations curves were linear in the range of 100-500 ng/ml aspirin (r=0.9997) and 10-110 ng/ml vitamin C (r=0.9991). It was found that; the method is considered precise and robust. Different commercial dosage forms were analyzed using the proposed method. Excellent results were obtained after comparing the F- and t- values of the proposed and reported methods. Chapter II: SERS for monitoring silver nanoparticles-induced antibacterial effect. The ability of SERS method in the analysis of the antibacterial effect of different shapes of AgNPs was described. Different reduction reactions were. carried out to produce different shapes of AgNPs. It was found that there is a relation between the geometry of the prepared AgNPs and the toxicity of it on Gram negative bacteria. Three different reference methods were carried out in order to test the effect of the three shapes of AgNPs on E.coli as a model example of Gram negative bacteria. Zone inhibition, growth curve and SERS methods were applied using the same concentration ranges of the prepared AgNPs in addition to Ampicillin as a positive control. The sensitive changes in the SERS spectra of the studied E.coli treated with the tested AgNPs allowed the suggestion of the mechanism of antibacterial effect of the prepared AgNPs. The effect of water chemistry on the toxicity of the studied AgNPs was tested. It was found that; the hexagonal shape of AgNPs is more toxic on the studied E.coli than the spherical and triangular NPs. This may be due to the acute edges of the hexagonal-AgNPs allow it to penetrate the bacterial cell wall and inhibit the protein synthesis which lead to cell death. Chapter III: Application of SERS as a stability indicating assay of some penicillins. This is the first trial of application of SERS as a detection and quantitation tool in the stability indicating assay of some penicillins, named, penicillin G, ampicillin and carbenicillin. The enhancement effect of the SERS monitoring was based on the hydroxylamine AgNPs which act as a SERS substrate. Penicilloic acid, the main degradation product, was reported as the main cause of allergic reactions after treating with some type of penicillins. The finger printing identification tool of the Raman spectroscopy allowed the proposed method to insitu detect the changes in the structure of the intact ampicillin as a representative example of the studied penicillins. The results obtained with the proposed SERS method were confirmed with LC/MS spectroscopy as a comparative method to elucidate the degradation products. |