The growing bacterial resistance against antibiotics creates a limitation for using traditional antibiotics and requests development of new approaches for treatment of bacterial infections. Among the bacterial infections that are most difficult to treat, biofilm-associated infections are one of the most hazardous. Consequently, the prevention of biofilm formation is a very important issue. One of the techniques that are widely investigated nowadays for this purpose is surface modification by polymer brushes that allows generating antifouling antibacterial surfaces. Previously, it was reported that salicylidene acylhydrazides (hydrazones) are good candidates as antivirulence drugs targeting the type three secretion system (T3SS). This secretion system is used by several Gramnegative pathogens, including Pseudomonas aeruginosa, to deliver toxins into a host cell. Furthermore, the chemical structure of these substances allows formation of complexes with metal ions, such as Fe3+ and Ga3+. The antibacterial activity of Ga3+ is well known and attributed to its similarity to the Fe3+ ion. It has also been shown that Ga3+ ions are able to suppress biofilm formation and growth in bacteria. In this thesis the chemistry of antibacterial and antivirulence Ga3+-Hydrazone complexes in solution was studied. First, to get insights in the solution chemistry, the protonation and the stability constants as well as the speciation of the Ga3+-Hydrazone complexes were determined. Additionally, a procedure for anchoring one of the hydrazone substances to antifouling polymer brushes was optimized, and the resulting surfaces were characterized. Results showed that the complexation with Ga3+ ions stabilizes the ligand and increases its solubility. Ga3+ ion binds to the hydrazone molecule forming a strong chelate that should be stable at physiological conditions. The different biological assays, such as Ga3+ uptake, antivirulence and antibiofilm effects, indicated very complex interaction of these complexes with the bacterial cell. Negatively charged and zwitterionic surfaces strongly reduced protein adsorption as well as biofilm formation. Therefore, the antifouling zwitterionic poly-[2-(methacryloyloxy)ethyl]dimethyl-3- sulfopropyl)-ammonium hydroxide (pMEDSAH) brushes were post-modified and successfully functionalized with bioactive substances via a block-copolymerization strategy. However, in order to maintain the availability of the bioactive substance after functionalization, the hydrophobic polyglycidylmethacrylate (pGMA) top block is probably better to functionalize with a lipophilic molecules to reduce diblock copolymer brush rearrangement.

Research Doctorate - Doctor of Philosophy (PhD) / This work presents the development and application of modern data acquisition and analysis techniques for the investigations of equilibrium and kinetic reactions. The analytical technique is known as second order global analysis and a background of this relatively novel approach has been given. The theory behind and characteristics of the computer programs developed analysis as part of this research are described in Chapter Two along with descriptions of the instrumentation and programs developed for the acquisition of both potentiometric and spectrophotometric data. Applications of the developed programs include a potentiometric and spectrophotometric study of the protonation and stability equilibria of a series of polydentate N-donor ligands, as detailed in Chapter Three. The combination of potentiometric and spectrophotometric analysis has been shown to be a powerful analytical tool. Spectrophotometric titrations were also combined with fast stop-flow experiments in order to elucidate the complex reaction mechanisms associated with helicating ligands. The helication of the ligand ‘PepdaH₂’ with copper(II) and nickel(II) is examined in Chapter Four, along with discussions concerning the ability to induce chirality in the helicates from the addition of a chiral counter ion. Investigations into chirality were further continued in Chapter Five where the stereoselectivity of a benzimidazole-based ligand was investigated with circular dichroism titrations. The synthesis and characterisation of the benzimidazole-based ligands are provided, including a study of the ability of the ligands to form higher order complexes as investigated using electrospray mass spectroscopy. Chapter Six provides an in-depth discussion concerning the use of combined glass hydrogen selective electrodes for the determination of equilibrium constants, as this was a major focus of this research. Different calibration techniques are discussed and a description of the internal calibration technique developed is provided along with examples of the advantages of performing internal calibration of the electrode.

The quantification of active principles is an indispensable stage of medicines quality control. For that reason a number of methodologies intended for pharmaceutical applications is constantly growing up. Thus, in view of great analysis demands, the development of low-cost, fast and automatized procedures is very useful. In this way, the present work proposes an analytical procedure for determination of paracetamol in pharmaceutical formulations employing Flow Injection Analysis (FIA) coupled to spectrophotometric detection. Interests for paracetamol is due to its large use as analgesic/antipyretic in Brazil. The proposed procedure is based on diazo-coupling reaction between sulfanilic acid and paracetamol in alkaline medium which forms an orange-reddish diazocompound that absorbs intensively at 500 nm. Optimization studies were carried out with experimental parameters and plotting a reference curve for determination of paracetamol. The linear work range including concentrations between 4.00 and 16.00 mg L-1 of paracetamol, with a correlation coefficient of 0.9991. The limit of detection for the considered work range shown be equal to 0.30 mg L- 1. The relative standard deviation to 10 replicates of the standard solution containing 8.00 mg L-1 of paracetamol was 1.28 %. The real sample analysis by the proposed procedure and by the official method demonstrated comparables results. The nominal amounts of paracetamol declared by the fabricants on the label of all analyzed pharmaceuticals formulations showed good agreement with the official specifications. Recovery studies in real samples revealed a mean rate of 97.1 % of the paracetamol standard added, assuring in such way the confidence of the proposed procedure. Studies realized in this work makes evident the viability of the use of the proposed procedure for determination of paracetamol, since this method has adopted an simple mechanized system, practice and produce results that do not differ significatively from the official method. Other advantages related at this procedure are the use of low toxic reagents and of low cost, good precision (repeatability) and reproducibility, generation of cromogenic product highly stable and suitable sensibility for quality control purposes. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A quantificação de princípios ativos é uma etapa indispensável do controle de qualidade de medicamentos, e em virtude disto, o número de metodologias desenvolvidas destinadas às aplicações farmacêuticas vem crescendo constantemente, visto que, diante de grandes demandas de análises, o desenvolvimento de procedimentos rápidos, pouco dispendiosos e automatizados é de grande valia. Desta forma, o presente trabalho propõe o desenvolvimento de procedimento analítico para determinação de paracetamol em formulações farmacêuticas empregando Análise por Injeção em Fluxo (FIA) associada à detecção espectrofotométrica. O interesse por este analito reside no fato deste fármaco ser um dos analgésicos/antipiréticos mais utilizados no Brasil. O procedimento proposto baseia-se na reação de diazoacoplamento entre ácido sulfanílico e paracetamol em meio alcalino com formação de um diazocomposto laranja-avermelhado que absorve intensamente em 500 nm. Foram realizados estudos de otimização dos parâmetros experimentais e construída uma curva de referência para determinação de paracetamol. A faixa linear de trabalho compreendem concentrações entre 4,00 e 16,00 mg L-1 de paracetamol, com um coeficiente de correlação de 0,9991. O limite de detecção para a faixa de trabalho considerada mostrou-se igual a 0,30 mg L-1. O desvio padrão relativo para 10 replicatas da solução padrão contendo 8,00 mg L-1 de paracetamol foi 1,28 %. As análises das amostras reais pelo procedimento proposto e pelo método oficial demonstraram resultados comparáveis. Os teores nominais de paracetamol declarados pelos fabricantes nos rótulos de todas as formulações farmacêuticas analisadas mostraram conformidades com as especificações oficiais. Estudos de recuperação em amostras reais revelaram uma taxa média de 97,1 % do padrão de paracetamol adicionado, garantindo desta forma a confiabilidade do procedimento proposto. Os resultados alcançados neste trabalho evidenciaram a viabilidade do emprego do procedimento proposto para a determinação de paracetamol, uma vez que este método adotou um sistema mecanizado simples, prático e quando aplicado para a quantificação de paracetamol em amostras comerciais produziu resultados que não diferiram significativamente do método oficial. Outras vantagens relacionadas a este procedimento são o uso de reagentes pouco tóxicos e de baixo custo, boa precisão (repetibilidade) e reprodutibilidade, geração de produto cromogênico altamente estável e com sensibilidade adequada para propósitos de controle de qualidade.

Coastal zones receive massive terrestrial inputs of nutrients and organic matter, and play an important role in biogeochemical cycles. The interactions of river inputs, ocean currents, atmospheric exchanges, anthropogenic influences, and biologically active ecosystems make CO2 system studies in coastal waters highly challenging. This work focuses on improving our understanding of the CO2 system in coastal waters through (1) development of a new methodology for measurements of CO2 system parameters in the field; (2) observations of large spatial and temporal CO2 system variations in coastal waters; and (3) characterization of the influence of organics on CO2 system behavior in coastal waters. A novel portable light-emitting-diode (LED) photometer was developed to provide low-cost seawater pH measurements in the field. With meta cresol purple (mCP) as the indicator, the photometer produces pHT measurements within ± 0.01 units of state-of-the-art spectrophotometric measurements (7.6 ≤ pH ≤ 8.2, 30 ≤ S ≤ 36.2, and 15 oC ≤ t ≤ 30 oC). With a simple “do-it-yourself” (DIY) construction design, a hundredfold reduction in cost relative to benchtop spectrophotometric systems, and routine calibration-free operation in the field, the DIY photometer is an ideal replacement for pH test strips or consumer-level potentiometric probes. Applications of special interest include education, citizen science, coastal zone monitoring, and aquaculture and aquarium management. Subannual variability of total alkalinity (TA) distributions in the northeastern Gulf of Mexico (GOM) was examined through the use of TA data from ship-based water sampling, historical records of riverine TA, and contemporaneous model output of surface currents and salinity. Variability of TA observed in the upper 150 m of the GOM water column was primarily controlled by subannual variations in the extent of mixing between seawater and river water. A transition in TA distribution patterns between the river-dominated northern margin (near the Mississippi–Atchafalaya River System) and the ocean current-dominated eastern margin (West Florida Shelf) was observed. A riverine alkalinity input index was developed to highlight riverine TA contributions. Contributions of organic alkalinity (Org-Alk) to TA were investigated in coastal waters from three different environments (estuary, urban, mangrove) and offshore sites in the Gulf of Mexico. The difference in alkalinity (∆TA) between TA measured by direct titration (TAmeas) and calculated (TAcal) from observations of DIC and pH was used as an estimate of Org-Alk. Average values of ∆TA were 0.1 ± 5.0 µmol kg-1 at coastal sample sites outside the Mississippi-Atchafalaya River Estuary (n = 17), 1.9 ± 5.2 µmol kg-1 in offshore waters (n = 14) in the northern Gulf of Mexico, 33.6 ± 18.0 µmol kg-1 in the Suwannee River Estuary (n = 17), and 16.0 ± 25.4 µmol kg-1 in sites that included Tampa Bay, the Caloosahatchee River, and the Ten Thousand Islands area (n = 55). In addition to Org-Alk assessments based on measurements of ∆TA, a novel two-step spectophotometric titration method was developed for the characterization of Org-Alk. Direct titrations showed substantial Org-Alk in coastal samples (n = 5), and the Org-Alk values obtained from the two-step titrations showed good agreement with results from ∆TA calculations. The spectrophotometric titration data were used in model fits to evaluate the dissociation constants (pKi) of the natural organic acids. The pKi of the organic acids were within the previously reported range for riverine fulvic acids.

O ion Co2+, quando coordenado com ligante bipiridina (bipy), pode ser reduzido por ataque químico de redutores fortes, como NaBH4 (boroidreto de sódio), formando [Co(I) (bipy)3]+, azul. Este complexo pode ser determinado espectrofotometricamente por conferir um espectro na região do visível com λmax = 600 nm (ε = 5,8x103 L.mol-1 .cm-1). Somente cobalto estabiliza-se na forma de [M(i)(bipy)3]+, enquanto que outros metais como Mn, Ni e Zn reduzem-se ao estado metálico. A estabilização do NaBH4 foi conseguida em DMF (N,N´-dimetilformamida). Foi utilizado o método da adição de padrão, condicionando-se o sistema ao meio H20:DMF na proporção de 2:1 (v/v) , T = 25°C, excesso de ligante e excesso de 240 vezes de NaBH4. Níquel interfere acima de 2,5x10-5 mol.L-1 , manganês acima de 5,0x10-5 mol.L-1 e zinco acima de 1,0x10-4 mol.L-1, quando CCO2+ = 5,0x10-5 mol.L-1. Este procedimento foi realizado em amostra NBS167, encontrando-se valores 1% menores que o valor certificado. / The cobalt (II) ion complexed with bipyridine (bipy) can be reduced chemically by reductant like sodium boronhydride yelding blue [Co(I)(bipy) 3]+. This complex can be determined spectrophotometrically using visible spectra at λ = 600 nm (ε = 5,8x103 L.mol-1 . cm-1). When Mn, Ni and Zn are present togheter with cobalt (II) and the mixture is complexed by bipyridine and furtherly treated by boronhydride, the ions of niekel, manganese and zinc are reduced to fundamental state remaining [Co(I)(bipy)3]+ soluble complex. The stabilization of NaBH4 was achieved in N,N\'-dimetilformamide (DMF). Interference studies showed for [Co2+] = 5,0x10-5 mol.L-1, 2:1 of H20:DMF, t = 25°C, excess presence of bipyridine ligand and 240 times excess of NaBH4 : nickel start interfere at 2,5x10-5 mol.L-1, manganese at 5,0x10-5 mol.L-1 and zinc at 1,0x10-4 mol.L-1. The procedure was apllied at a cobalt alloy NBS167 using standard addition method and the recovery was 1% less than certificated value.

Objetivos: os objetivos gerais deste trabalho foram desenvolver, validar e comparar métodos analíticos para caracterização e determinação quantitativa de vildagliptina (VLG) na forma farmacêutica comprimidos, assim como determinar a cinética de degradação do fármaco em condição de estresse. Métodos: método indicativo de estabilidade por cromatografia líquida de alta eficiência com detecção ultravioleta (CLAE-UV) foi desenvolvido e validado, conforme as normas da International Conference on Harmonisation (ICH). A cinética de degradação do fármaco foi determinada frente à hidrólise alcalina. A possível estrutura do produto de degradação majoritário, formado sob condições básicas, oxidativas e térmicas foi proposta de acordo com análises realizadas por espectrometria de massas (EM). Foi desenvolvido e validado, também, método por espectrofotometria ultravioleta derivada para quantificação do fármaco na forma farmacêutica. Resultados e Conclusões: o método de CLAE indicativo de estabilidade desenvolvido e validado demonstrou ser adequado para a quantificação da substância ativa na forma farmacêutica sem sofrer a interferência dos excipientes presentes na formulação e também na presença dos produtos de degradação. Os principais fatores extrínsecos que promoveram a degradação do fármaco foram: oxidação, hidrólise alcalina e temperatura. Determinou-se a cinética de degradação, sob condições alcalinas, como sendo de primeira ordem indicando, assim, que o processo de degradação é dependente da concentração de fármaco. O método por espectrofotometria UV derivada também se mostrou adequado para a quantificação de vildagliptina nos comprimidos. A comparação entre os métodos desenvolvidos não mostrou diferença estatística significativa demonstrando que ambos os métodos podem ser utilizados para determinação de vildagliptina no controle de qualidade dos comprimidos. / Objectives: the aim of the present work was to develop, validate and compare analytical methods to characterization and quantitative determination of vildagliptin (VLG) in tablet dosage form, as well as to determinate the degradation kinetics of the drug in a stress condition. Methods: stability-indicating method for the analysis of VLG by high performance liquid chromatography (HPLC) with ultraviolet detection was developed and validated according to the International Conference on Harmonisation (ICH) guidelines. The degradation kinetics of the drug under the alkaline hydrolysis was determined. The possible molecular structure of the major degradation product obtained under the stress studies by alkaline hydrolysis, oxidation and thermal degradation was predicted by mass spectrometry (MS) Results and Conclusions: The developed stability-indicating method was adequate to determine the active substance in the formulation even in the presence of the excipient ingredients in the formulation and, also, in the presence of the degradation products. The main extrinsic factors which promoted the drug degradation were: oxidation, alkaline hydrolysis and thermal degradation. The degradation kinetics was determined, under alkaline conditions, as first order showing that the process is dependent on the drug concentration. The derivative spectrophotometric method also was adequate to the quantification of vildagliptin in tablets. There was no statistical significant difference between the methods demonstrating that both methods can be used for the determination of vildagliptin in quality control of pharmaceutical tablets.

Biogeochemical changes across oceanic interfaces, and method development to study such changes, are described in this work. The interfaces studied include the Subtropical Front in the Pacific Ocean and the boundary at the base of the euphotic zone. Both interfaces are characterized by accumulations of phytoplankton, although the forcing functions that result in increased biomass are distinctly different. The Subtropical Front, located at approximately 30°N in the Pacific Ocean, was detected during a cruise in the summer of 2002 by its diagnostic 34.8 salinity outcrop, in spite of the absence of its associated temperature signature. The front displayed elevated concentrations of large diatoms; Rhizosolenia and Hemiaulus, with concentrations penetrating deeper in the water column south of the front. Rhizosolenia species were dominant on the warmer, high salinity side of the front, while Hemiaulus prevailed on the cooler, low salinity side. While high cell counts were enumerated by net tows, the elevated biomass was not visible in satellite color imagery. Size fractionated chlorophyll data revealed > 10 um cells were found below 200 m, indicating export of large cells out of the euphotic zone. This confirms observations by other investigators that fronts represent important regions of episodic export, although such export may go undetected if the biomass is not visible in ocean color images. Another region of interest was the narrow layer at the base of the euphotic zone. During stratified conditions, the layer was characterized by a fluorescence maximum, a primary nitrite maximum, and a nutricline. While fluorescence maxima have proven easy to detect using commercial fluorometers, nutrient distributions have proven more difficult. The Spectrophotometric Elemental Analysis System (SEAS) permitted detection of low concentrations of nitrite, nitrate, and phosphate with nanomolar sensitivity and 1 Hz or better sampling frequency. Using multiple wavelength spectroscopy, the range of nitrate concentrations from 2 nM to 20 uM have been detected. Profiles of nitrite obtained across the North Pacific Subtropical Gyre revealed the close correlation between nitrite and chlorophyll fluorescence maxima, suggesting that the nitrite maximum is formed by phytoplankton when insufficient light is available to permit reduction of nitrite to ammonia.

A espécie Uncaria tomentosa (Rubiaceae) é reconhecida por diversos povos sul-americanos, devido a sua importância etnofarmacológica. Na sua maioria, os estudos realizados com U. tomentosa empregam como matéria prima vegetal a casca, devido à fração rica em alcalóides. Entre os constituintes químicos relatados para a espécie destacam-se os flavonóides, triterpenos e alcalóides, aos quais é atribuído um número significativo de propriedades terapêuticas. A escassez de metodologias analíticas para o doseamento do teor de alcalóides de U. tomentosa motivou a realização do presente trabalho, que visa à validação de metodologia analítica para matéria prima vegetal (DVSM), extrato seco (ESC) e cápsulas contendo extrato seco de Uncaria tomentosa DC. O estudo propôs a utilização de metodologia espectrofotométrica e cromatográfica para a quantificação de teores totais de alcalóides. Para fins de identificação da espécie foram utilizados métodos cromatográficos por CCD, preconizados para flavonóides e alcalóides. O perfil por CCD encontrado para a DVSM, liofilizado e ESC foi diferente do relatado na bibliografia. O teor de alcalóides do extrato seco comercial (ESC), utilizando método espectrofométrico foi de 8,41 mg/g, apresentando uma taxa de recuperação de 100,45%. Paralelamente, foi desenvolvido e validado um método de análise por CLAE para o ESC, que permitiu a quantificação da fração alcaloídica, expressa como isomitrafilina. O teor de alcalóides totais encontrado foi de 14,58 mg/g e apresentou taxa de recuperação de 99,95 a 100,44%. No teste de robustez do método analítico por CLAE, o ESC apresentou variações significativas com a variação do pH e da temperatura. O ESC contido em cápsulas de gelatina foi testado quanto à estabilidade térmica, por um período de 90 dias, a 50 ± 2 ºC e 90 ± 5% de umidade relativa. O perfil de alcalóides totais foi obtido por CLAE e ao ser comparado com o ESC, não exposto a condições extremas, apresentou teores equivalentes, porém, com mudança no perfil da fração alcaloídica, o que pode caracterizar produtos de degradação. Um perfil similar foi observado quando o ESC foi exposto à luz UVC por 90 dias. / Uncaria tomentosa DC (Rubiaceae; cat’s claw) is a climbing bush widespreads in the tropical South American countries, in which its etnopharmacological importance is largely recognized. The main phytochemical studies on U. tomentosa revealed a meaningful alkaloid fraction in its aerial parts and especially on its bark. Besides that, other relevant components were also isolated from its bark, including flavonoids and triterpenes, to which several pharmacological properties were formerly ascribed. Notwithstanding the crescent importance in the research of novel drugs, it is to denote the lack of official and validated analytical methods intended for the determination of the alkaloids content in U. tomentosa. Thus, the aim of this work was the development and validation of analytical method which allow the analysis and content determination of the main alkaloids in the vegetal raw material (DVSM), a commercial dry extract as well as in gelatin hard capsules containing it. For this purpose, a spectrophotometric method and a chromatographic one were developed and afterwards validated. In both cases the total alkaloids content was expressed as isomitraphiline (reference standard). The identification by CCD analysis was carried out on basis to several methods related earlier in the literature for flavonoids and alkaloids. In general, the comparison from CCD profiles of genuine samples of U. tomentosa bark depicted in the literature, DVSM, dry extract and ESC profiles led to partial dissimilar results, which reinforce the need of additional efforts in this way. The alkaloids content calculated spectrophotometrically for the commercial dry extract (ESC) was 8,41 mg/g, with a recover of 100,45%. For the HPLC method, the total alkaloids content correspond to the sum of the area under the peaks previously characterized as alkaloids. The alkaloids content calculated for the same extract by HPLC was 14.58 mg/g, with a recover rate of 99,95 to 100,44%. The method as a whole fulfills the usual ICH validation requirements. The stability test under stress conditions of pH and temperature for the ESC presented a significant variation of the individual area of some peaks. The original peaks assigned to isomitraphiline, pteropodine and isopteropodine showed a decrease in intensity and a concomitant appearance of new peaks, originated from breakdown process presumably. A similar profile was observed by exposing ESC samples to the wave short UV radiation during 90 days. There are also evidences in favor of degradation signals in non-treated ESC samples.

Objetivos: os objetivos gerais deste trabalho foram desenvolver, validar e comparar métodos analíticos para caracterização e determinação quantitativa de vildagliptina (VLG) na forma farmacêutica comprimidos, assim como determinar a cinética de degradação do fármaco em condição de estresse. Métodos: método indicativo de estabilidade por cromatografia líquida de alta eficiência com detecção ultravioleta (CLAE-UV) foi desenvolvido e validado, conforme as normas da International Conference on Harmonisation (ICH). A cinética de degradação do fármaco foi determinada frente à hidrólise alcalina. A possível estrutura do produto de degradação majoritário, formado sob condições básicas, oxidativas e térmicas foi proposta de acordo com análises realizadas por espectrometria de massas (EM). Foi desenvolvido e validado, também, método por espectrofotometria ultravioleta derivada para quantificação do fármaco na forma farmacêutica. Resultados e Conclusões: o método de CLAE indicativo de estabilidade desenvolvido e validado demonstrou ser adequado para a quantificação da substância ativa na forma farmacêutica sem sofrer a interferência dos excipientes presentes na formulação e também na presença dos produtos de degradação. Os principais fatores extrínsecos que promoveram a degradação do fármaco foram: oxidação, hidrólise alcalina e temperatura. Determinou-se a cinética de degradação, sob condições alcalinas, como sendo de primeira ordem indicando, assim, que o processo de degradação é dependente da concentração de fármaco. O método por espectrofotometria UV derivada também se mostrou adequado para a quantificação de vildagliptina nos comprimidos. A comparação entre os métodos desenvolvidos não mostrou diferença estatística significativa demonstrando que ambos os métodos podem ser utilizados para determinação de vildagliptina no controle de qualidade dos comprimidos. / Objectives: the aim of the present work was to develop, validate and compare analytical methods to characterization and quantitative determination of vildagliptin (VLG) in tablet dosage form, as well as to determinate the degradation kinetics of the drug in a stress condition. Methods: stability-indicating method for the analysis of VLG by high performance liquid chromatography (HPLC) with ultraviolet detection was developed and validated according to the International Conference on Harmonisation (ICH) guidelines. The degradation kinetics of the drug under the alkaline hydrolysis was determined. The possible molecular structure of the major degradation product obtained under the stress studies by alkaline hydrolysis, oxidation and thermal degradation was predicted by mass spectrometry (MS) Results and Conclusions: The developed stability-indicating method was adequate to determine the active substance in the formulation even in the presence of the excipient ingredients in the formulation and, also, in the presence of the degradation products. The main extrinsic factors which promoted the drug degradation were: oxidation, alkaline hydrolysis and thermal degradation. The degradation kinetics was determined, under alkaline conditions, as first order showing that the process is dependent on the drug concentration. The derivative spectrophotometric method also was adequate to the quantification of vildagliptin in tablets. There was no statistical significant difference between the methods demonstrating that both methods can be used for the determination of vildagliptin in quality control of pharmaceutical tablets.

This work deals with the content of iodine in soils, furthermore with obtaining and processing samples from four selected sampling areas, all of which are in the proximity of the Arnoštov settlement in district Prachatice in the foothills of Šumava. The soil samples were obtained from forest, meadow, pasture and fallow soil in 2009 to 2011. The iodine content in the soils was determined by using the spectrophotometric method, which had been optimized for the soil samples. Iodine concentration in lysimeter water was determined by using method inductively coupled plasma - mass spectrometry. The results obtained from each sampling areas were compared with each other and with the results from other areas. Consequently, the iodine concentration results in the soils were compared with the iodine concentration in lysimeter waters. It was found, that the highest iodine content in soils was measured in a sample obtained from Area 1 (meadow), part B in a depth of 16 - 30 cm in June of 2009, namely a content of 8,67 mg of I per kg of dry soil. The lowest content of 1,42 mg of I per kg of soil was found in the area 4 (forest), sample obtained in June of 2010, in the L horizon. By comparing iodine content with iodine concentrations in lysimeter waters, it was concluded that the concentration of iodine in lysimeter waters does not depend on iodine concentrations in soils and that it does not even represent the absolute iodine content in soil, as was determined by comparing the results from Arnoštov with data acquired from Agrovýzkum Rapotín in Jeseníky.