The present study was focused to develop an analytical method to analyse â-lactam antibiotics present in aqueous solutions and able to be applied directly in the fields. The method here presented is based on the chemical reaction between â-lactam antibiotics with phosphomolybdic acid, a heteropolyacid able to be reduced by the thiols obtained after the acid hydrolysis of the â-lactam antibiotics. The blue product obtained, which is proportional to the antibiotic amount, is adsorbed on polyurethane foam, and the intensity of color is directly evaluated on the solid material by means of diffuse reflectance spectroscopy. For all six evaluated â-lactam antibiotics (amoxicillin, ampicillin, penicillin V, penicillin G, cefotaxime, cefuroxime), the analytical parameters achieved were: LOD = 0.03 µg/ml, LOQ = 0.1 µg/ml, RSD = 4.0 %. The study of possible interferences showed that using solid phase extraction is possible to eliminate even strong interferences as ascorbic acid, cysteine and reducing salts like stannous chloride. The present method has avoided, as much as possible, the use of expensive and contaminating solvents and chemical reagents. The method presents the possibility to be applied using only a desktop scanner and a personal PC for measuring the color of the adsorbed material on the PUF.

A new detector for gas chromatography based on a microwave induced plasma has been developed. In order to record chromatograms emission spectra of diatomics are detected. Also a new method to obtain qualitative information on the analysed organic compound has been developed. The new detection method allows to get information about the atomic composition. In some cases the detector signals can be correlated with the constitution of the analysed substance. The detection method is based on the simultaneous detection of the spectral density of molecular bands of different diatomics as CC, CH, CN, NH, OH and an atomic hydrogen line. The resulting peak areas and the offset of the OH band are correlated with the analysed compounds by multivariate linear regression.

The photocycloadditions of 2-(dialkylamino)propenenitriles to 1-acetylnaphthalene in d6 benzene as solvent proceed with high directional selectivity by fast and photoreversible formation of [2+2]-cycloadducts (tetrahydrocyclobuta[a]naphthalenes) followed by a slower and photoirreversible formation of [4+2]-cycloadducts (1,4-dihydro-1,4-ethanonaphthalenes). With increasing duration of irradiation the product pattern is shifted towards a mixture of diastereomeric [4+2]-adducts in which the isomer with endo-orientation of the dialkylamino group in the ethano bridge is predominating. The endo-[4+2]-adduct of 2-(dipropylamino)-propenenitrile to 1-acetylnaphthalene was isolated in pure form, and its configuration was unambiguously corroborated by a single crystal X-ray structure analysis. Upon thermal activation it is converted in a small fraction via an intermediate biradical to the thermodyna-mically more stable exo-epimer before it is decomposed to the educts. Methyl 1-naphthoate reacts in the same way as 1-acetylnaphthalene but less efficiently.

The use of ICP-OES to determinate Rare Earth Elements in different matrices often fails because of high spectral interferences. To achieve an correct result the use of a sample preparation is advisable. In this work Extractionchromatography is used as sample preparartion. Three different substances were used as stationary phase. These are Triazaheptan-1,4,7,7-tetraaceticacid (DETATA), Tetraphenylmethylendiphosphineoxide. (TPMDPO) und Tri-n-octylphosphineoxide (TOPO). If DETATA is used as staionaric phase the recovery of REE in the final solution is reduced to 40-60% when bivalent ions such as Ni2+ and Fe2+ are present in the sample. So this substance is not reliable in the use as stationaric phase if the sample is a steelmatrix. In highly concentrated KCl-solution as matrix the recovery of REEs increases to 98%. In the second part the results of the experiments with TPMDPO are presented. In the presence of Cr3+, Ni2+ oder Mn2+ the recovery decrease significantly. So this substance is also unusable if the matrix is steel. The third examined organic substance is TOPO. If NH4NO3 is added as salting-out material and after reducing the solution with hydrazine the recovery of REEs is qunatitative. The improvement of the detection limit exceeds the factor of 10 if ICP-OES is the used analysing method.

The active site of the NiFe-hydrogenase from <i>Desulfovibrio vulgaris</i> Miyazaki F was investigated by means of X-ray Absorption Spectroscopy (XAS). Using the Extended X-ray Absorption Fine Structure (EXAFS) the active site was structurally characterized to determine differences between four different catalytic states of the enzyme. The nature of an additional ligand which is present in the oxidized forms of the enzyme was revealed and the distance between both metal atoms of the heterobinuclear site was calculated. Suitable data analyzation techniques were developed using simulated spectra. For the verification of these techniques, spectra from model compounds structurally characterized by other methods were used. To ensure sufficient quality of the spectra a newly developed quality control system using statistical criteria was employed.

Porous Carbon Blacks with specific surfaces of up to 1475 m²/g were examined and characterized by ¹²⁹Xe NMR spectroscopy. Graphite is regarded as a not-porous reference. The porosity of Carbon Blacks can be divided in three categories: inter-aggregate, intra-aggregate and intra-particle pores. A reciprocal behavior of the chemical shift to the middle pore radius has been found. Here the pressure and temperature dependence of the chemical shift are to be considered and only with pressures over 8-12 bar a characteristic limit value is reached. The diffusion coefficient of the intra-porous xenon atoms was determined with the help of the PFG NMR spectroscopy and lies with ambient temperature and a pressure from 10 to 12 bar within the range of 3·10^-9 to 3·10^-8m²/s. The adsorption in micro-porous Carbon Blacks can be described by the pore filling theory of Dubinin and co-workers.

The main point of this thesis is the validation of SA-ICP-MS for routine analysis in the steel industry. Therefor a new interface-system is build up in order to measure transient siganls from the continuos ablation process of the spark device. Further more the coupling of an ETV oven for slurry analysis and a Laser Ablation for isitope ratio determination is discriebed. Some fundamental aspects in formation of interference in ICP-MS are pointed out at the end of this thesis.

In the present thesis the development of an analytical method for the determination of trace amounts of iron in dichlorosilane by graphite furnace atomic absorption spectrometry with a modified autoprobe unit is described. An conceived gas inlet system enabled a nearly contamination free and constant gas injection. The analytical method is optimized and the iron concentration in dichlorosilane is quantitatively determined.

The context of this work examines the influence of zinc sulfide (ZnS) and other inorganic substances (Sb2O3, Sb2S3, Sn, Zn ) on the cross-linking reactions of the conjugated double bond sequences, which are generated as a consequence of thermal dehydrochlorination reactions of poly(vinyl chloride) (PVC). With increasing cross-linking grade, the flammability of the corresponding PVC would be decreased due to the suppression of fragmentation reactions. In this work element balances of thermal degrading PVC samples with inorganic additives are analyzed, as well as thermogravimetric investigations are consulted. Apart from qualitative views a kinetic model of the dehydrochlorination reactions is developed using multivariate nonlinear regression analysis of thermogravimetric data. The changes in the thermally stressed polymer samples under argon and under oxygen admission are observed using different analytic techniques (visual video monitoring, infrared spectrometry, and scanning electron microscopy). It can be shown that during the thermal degradation of PVC the cross-linking reactions can be increased by several inorganic additives.

The development of analytical procedures for the analysis of selected reactive process gases in order to use them in the production of semiconductors without sample preparation is the main task of the presented work. Different atomic spectrometric methods e.g. Electrothermal Atomic Absorption Spectrometry (ETAAS), Microwave Induced Plasma Atomic Emission Spectrometry (MIP-AES), Non dispersive Atomic Fluorescence Spectrometry and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) have been used for the development of the procedures. The physico-chemical features of the matrix request a fitted sampling e.g. suitable, non corrosive material of the tubes and unions, and modified analytical system. The described ETAAS system with an automated sampling system allows the determination of Cu, Fe and Ni in gaseous HCl, Cl2, BCl3 and SiH2Cl2 without sample preparation. A comparison of calibration with standard aqueous solutions as well as standard additions and calibration with a gaseous standard has shown the negligible influence of the matrix on the calibration using the ETAAS system.