Orientador: Juliana Azevedo Lima-Pallone / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-20T21:26:18Z (GMT). No. of bitstreams: 1 Rebellato_AnaPaula_M.pdf: 1287593 bytes, checksum: 661e828d074dab6ac68c3fad61029313 (MD5) Previous issue date: 2012 / Resumo: No Brasil a ANVISA através da Resolução nº 344 de 2002, instituiu a obrigatoriedade do enriquecimento de farinhas de trigo e milho com ácido fólico e ferro. A deficiência de ferro é apontada como a principal causa da anemia ferropriva. A fortificação de alimentos com ferro é a estratégia indicada pelas instituições que atuam na área de saúde como a mais eficiente para o combate à anemia. Entretanto, a ingestão excessiva deste mineral está associada a danos oxidativos e tem sido relacionada com a manifestação de várias doenças. Dessa forma, o alcance dos objetivos dos programas de fortificação de alimentos está relacionado à garantia da ingestão recomendada para os nutrientes adicionados e aos atributos físico-químicos, que devem ser monitorados no veículo utilizado e no produto final. Este trabalho teve como objetivos adequar e validar uma metodologia para a determinação de ferro em amostras de biscoitos elaborados com farinha de trigo fortificada, utilizando a técnica de Espectrometria de Absorção Atômica com chama e acompanhar os parâmetros físico-químicos (umidade, acidez, índice de peróxido e teor de lipídeos) durante o período de estocagem (150 dias). O método para determinação do teor de ferro em biscoitos foi validado para os parâmetros precisão, seletividade, recuperação, sensibilidade, linearidade, limite de detecção (LD) e limite de quantificação (LQ) e se mostrou adequado. O teor médio de ferro presente nos biscoitos tipo cream cracker, água e sal, maisena e amanteigado foram: 5,0 a 8,6; 5,3 a 7,8; 2,5 a 6,8; 3,7 a 5,7 mg 100 g-1, respectivamente. Foi verificada diferença significativa entre lotes de mesma marca e entre marcas do mesmo tipo, através da ANOVA e do Teste de Tukey (p<0,05). Para os parâmetros físico-químicos, os valores obtidos ao longo do período de estocagem variaram; umidade de 1,8 a 6,3%; acidez de 1,5 a 7,4 mg NaOH 0,1 mol L-1 100g-1; índice de peróxido de valor não detectado (nd) a 95,1 meq Kg-1 de gordura. Para o teor de lipídeos e ferro, o menor e o maior valor encontrado foram 9,8 e 18,0% e 2,1 e 9,2 mg 100 g-1, respectivamente. Foi possível verificar que existe diferença significativa entre os valores obtidos para cada lote de mesma marca ao longo do período de estocagem. Nenhum tipo de correlação entre a umidade e os valores de acidez presentes nas matrizes, foi observado, da mesma forma que não foi verificada nenhuma correlação entre o índice de peróxido e o teor de ferro. Notou-se que há necessidade de melhorar a qualidade dos ingredientes utilizados no preparo dos biscoitos a fim de manter um padrão de qualidade uniforme durante todo o período de validade. As variações observadas no teor de ferro indica a necessidade de uma legislação mais específica, estabelecendo concentrações (mínima e máxima) para o mineral utilizado na fortificação de farinha de trigo que estará presente em alimentos prontos para o consumo, a fim de garantir o sucesso da campanha de fortificação / Abstract: Through the resolution no. 344 of 2002, ANVISA (Brazilian Regulatory Institute) assigned the obligation of enriching wheat and corn flours with folic acid and iron. Iron deficiency is pointed out as the main cause of anemia, so food fortification with this mineral is the most efficient strategy indicated by the health institutions that work towards the combat of anemia. However, excessive ingestion of this mineral is associated with oxidative damages and has also been related to the occurrence of several diseases. So the fortification programs must guarantee the recommended intake, and not more than that, as well as to maintain the physicochemical attributes, by monitoring both the vehicle of fortification and the final product. This work redesigned and validated one methodology for iron determination in samples of biscuits produced with fortified wheat flour, by using Flame Atomic Absorption Spectrometry (FAAS). It also measured physicochemical parameters (moisture, acidity, peroxide index and fat content) during the storage period (150 days). The method for iron determination in biscuits is shown to be adequate and was validated for the parameters precision, sensibility, selectivity, recovery, accuracy, linearity, limit of detection (LOD) and quantification (LOQ). The iron content in biscuits of the types cream cracker, salt and water, cornstarch cookies (maizena) and butter cookies were, respectively: 5.0 to 8.6, 5.3 to 7.8, 2.5 to 6.8, and 3.7 to 5.7 mg 100 g-1. ANOVA and Tukey tests (p<0,05) were applied to verify if there was significant difference between batches of the same brand and among the brands of the same type of biscuits. For the physicochemical parameters, all the values obtained throughout the storage period varied. Moisture was from 1.8 to 6.3%; acidity was from 1.5 to 7.4 mg NaOH (0,1 mol.L-1) 100 g-1; peroxide index was form non-detectable (nd) to 95.1 meq Kg-1 of fat. The lowest and the highest values for fat content were 9.8 and 18% the range for iron was from 2.1 to 9.2 mg 100 g-1 for iron. There was significant difference between the values obtained for each batch of the same brand throughout the storage period. But there was no correlation between the moisture present in the matrix and the acidity values, neither there was between the peroxide index and iron content. It is necessary for the industries of biscuits to improve the stability of the ingredients to maintain uniformity during all the storage period. The observed variation of iron content indicates the need for a more specific legislation, which establishes minimum and maximum concentrations for the mineral added to fortify wheat flour, aiming to guarantee the success of the fortification campaign / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

Orientador: Juliana Azevedo Lima Pallone / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T00:41:22Z (GMT). No. of bitstreams: 1 Silva_GrasieladeSouzaCostada_M.pdf: 1118428 bytes, checksum: e1f018de2c7cef443ff93a0651ba4dd0 (MD5) Previous issue date: 2012 / Resumo: Com o objetivo de diminuir a anemia ferropriva a fortificação de alimentos com ferro tem se tornado uma prática comum em todo o mundo. De acordo com estimativas do Ministério da Saúde, cerca de 45% das crianças brasileiras de até 5 anos (10 milhões de pessoas) têm anemia. Entretanto, trabalhos científicos apontam que a ingestão excessiva de ferro pode estar associada a danos oxidativos em células e tecidos e tem sido relacionado com a incidência de doenças como Parkinson, acidente vascular cerebral, Alzheimer, esclerose múltipla, catarata, cardiopatias, artrite e diabetes, entre outras. Além disso, outros estudos sugerem que a suplementação com ferro, pode comprometer o aproveitamento do zinco no organismo humano, levando a outros problemas, como nanismo, má cicatrização, cirrose hepática, menstruação irregular, depressão e deficiência no sistema imune dentre outros. As farinhas fortificadas com ferro já estão disponíveis no mercado nacional desde 2004, porém, são poucos os dados sobre o controle dos níveis de ferro, bem como a razão molar entre ferro e zinco (naturalmente presente), em alimentos elaborados com farinhas fortificadas, sendo a razão molar desejada cerca de 4:1 para não prejudicar o aproveitamento do zinco pelo organismo. Esta pesquisa foi desenvolvida com o objetivo de avaliar ferro, zinco e umidade em pães industrializados elaborados com farinhas fortificadas. Para as análises do teor dos minerais foi utilizada a Espectrometria de Absorção Atômica com chama (FAAS) e para umidade, secagem em estufa. Para validação parcial, foram analisados os parâmetros sugeridos pelo INMETRO. Os resultados obtidos para linearidade através do coeficiente de correlação foi de 0,9994 para ferro e 0,9996 para zinco. A precisão apresentou um coeficiente de variação para ferro e zinco menor que 6%. A exatidão apresentou faixa de recuperação entre 91 a 109% para ferro e 87 a 108% para zinco. Os limites de detecção e quantificação foram de 0,04 e 0,15 mg L-1 para ferro e 0,07 e 0,24 mg L-1 para zinco, respectivamente, demonstrando que o método escolhido é sensível, eficiente e preciso. Os resultados obtidos para repetitividade na determinação de umidade não ultrapassam o coeficiente de variação 2,0%, mostrando que o método é adequado. Os teores de ferro e zinco nas amostras de pães variaram de 2,2 a 6,0 mg 100 g-1 (4,1 mg 100 g-1 em média) e 0,3 a 1,0 mg 100g-1 (0,7 mg 100 g-1 em média) no pão tradicional; de 1,8 a 4,1 mg 100 g-1 (3,0 mg 100 g-1 em média) e 1,4 a 2,3 mg 100 g-1 (1,9 mg 100 g-1 em média) no pão integral; de 1,8 a 6,8 mg 100 g-1 (4,3 mg 100 g-1 em média) e 1,7 a 2,8 mg 100 g-1 (2,3 mg 100 g-1 em média) no pão 7 grãos; de 3,0 a 3,8 mg 100 g-1 (3,4 mg 100 g-1 em média) e 1,8 a 3,0 mg 100 g-1 (2,4 mg 100 g-1 em média) no pão 9 grãos; de 2,0 a 4,2 mg 100 g-1 (3,1 mg 100 g-1 em média) e 1,4 a 2,5 mg 100 g-1 (2,0 mg 100 g-1 em média) no pão 12 grãos, respectivamente. Os resultados indicaram, em geral, falta de uniformidade no teor de ferro e zinco entre lotes da mesma marca e entre marcas do mesmo tipo de pão. No pão tradicional esta falta de homogeneidade, provavelmente, ocorra pela dificuldade na adição da pré-mistura (ácido fólico e ferro) na farinha, ingrediente principal na produção de pães, enquanto que nos pães especiais, o comportamento observado pode ser explicado pela variedade e quantidade de grãos adicionados. A razão molar Fe:Zn variou de 5:1 a 12:1 no pão tradicional; 2:1 a 3:1 no integral; 1:1 a 3:1 no 7 grãos; de 1:1 a 2:1 no 9 grãos e no pão 12 grãos não houve variação, sendo a razão molar 2:1. No pão tradicional foi encontrado uma razão molar Fe:Zn maior que 4:1, podendo assim prejudicar o aproveitamento do zinco pelo organismo / Abstract: Iron food¿s fortification has become a common practice around the world in order to reduce anemia caused by iron deficiency. Ministry of Health estimates that approximately 45% of Brazilian children up to 5 years (10 million people) have anemia. However, scientific studies indicate that excessive intake of iron may be associated with oxidative damage to cells and tissues has been associated with the incidence of diseases like Parkinson's, stroke, Alzheimer's, multiple sclerosis, cataracts, heart disease, arthritis and diabetes, among others. Also, other studies suggest that iron supplementation may compromise the use of zinc in the human body, leading to other problems such as stunting, poor wound healing, liver cirrhosis, irregular menstruation, depression and disability in the immune system among others. The flour fortified with iron are available in the market since 2004, however, there are few data on the control of iron levels, as well as the molar ratio between iron and zinc (naturally present), foods made with fortified flour, being desired molar ratio about 4:1 to not damage the recovery of zinc by the body. This research was developed to assess iron, zinc and humidity in industrial bread made with fortified flour. For minerals analysis were used atomic absorption spectrometry with flame (FAAS) and humidity, drying in an oven. For partial validation, we analyzed the parameters suggested by INMETRO. Results of linearity was obtained by the correlation coefficient of 0,9994 and 0,9996 for iron and zinc, respectively. The accuracy showed a coefficient of variation for iron and zinc less than 6%. The accuracy showed recovery range between 91 to 109% for iron and 87 to 108% for zinc. The limits of detection and quantification were 0,04 and 0,15 mg L-1 for iron and 0,07 to 0,24 mg L-1 for zinc, showing that the chosen method is sensitive, accurate and efficient. The results obtained to determination of repeatability humidity were not greater than the coefficient of variation 2,0%, showing that the method is appropriate. The levels of iron and zinc in samples of breads varied from 2,2 to 6,0 mg 100 g-1 (4,1 mg 100 g-1 on average) and 0,3 to 1,0 mg 100g-1 (0,7 mg 100 g-1 on average) in traditional bread; 1,8 to 4,1 mg 100 g-1 (3,0 mg 100 g-1 on average) and 1,4 to 2,3 mg 100 g-1 (1,9 mg 100 g-1 on average) in whole wheat bread; 1,8 to 6,8 mg 100 g-1 (4,3 mg 100 g-1 on average) and 1,7 to 2,8 mg 100 g-1 (2,3 mg 100 g-1 on average) in 7 grain bread ; 3,0 to 3,8 mg 100 g-1 (3,4 mg 100 g-1 on average) and 1,8 to 3,0 mg 100 g-1 (2,4 mg 100 g-1 on average) in 9 grain bread; 2,0 to 4,2 mg 100 g-1 (3,1 mg 100 g-1 on average) and 1,4 to 2,5 mg 100 g-1 (2,0 mg 100 g-1 on average) in 12 grain bread, respectively. The results showed, in general, lack of uniformity in the content of iron and zinc between batches of the same brand and between brands of the same type of bread. In traditional bread this lack of homogeneity, probably occurs by the difficulty in adding premix (folic acid and iron) in the flour, the main ingredient in bread production, while in specialty breads, the behavior can be explained, variety and amount of grain added. The molar ratio of Fe: Zn ranging from 5:1 to 12:1 in traditional bread; 2:1 to 3:1 in whole wheat bread; 1:1 to 3:1 in 7 grain bread; 1:1 to 2:1 in 9 grain bread and 12 grain bread did not change, and the molar ratio of 2:1. Has been found in traditional bread molar ratio Fe Zn greater than 4:1 and can thus damage the recovery of zinc by the body / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

The literature relevant to the generation of volatile hydrides for analytical atomic spectroscopy has been reviewed, with particular reference to atomic absorption spectrometry (AAS). This reveals some conflicting information concerning the nature of various interference effects and strategies to overcome them. The use of flow injection (FI) procedures has been demonstrated by several research groups, to be beneficial. A review of the literature concerning the application of FI techniques to AAS shows that there is a sustained interest in the use of such a combination for analytical purposes. In particular, an interest in the on-line coupling of chemical pretreatment of samples is evident. Atomic absorption spectrometry has a limited working range and requires frequent calibration, consequently, there is a need for a rapid, precise on-line dilution procedure. The potential of FI systems with wide bore manifold tubing for on-line dilution was assessed and found to be limited by variations in dispersion coefficient arising from differences in specific gravities between the sample and carrier fluids. This could be overcome only by the use of unrealistically high flow rates. The use of FI procedures for the generation of volatile hydrides of selenium and arsenic was investigated. Optimization studies of system parameters, including the atomization step, were undertaken which demonstrated the benefits in applying FI in hydride generation atomic absorption spectrometry (HGAAS). Analytical methods were devised and evaluated for the determination of Se in copper metal and As in nickel alloy. These procedures involved the use of an on-line matrix removal step in which potentially interfering matrix elements were retained on a strong cation exchange resin (Dowex 50W). The manifold was designed so that the FI value acted as the interface between the matrix isolation stage and the vapour generation stage, a strategy which allowed independent optimization of each stage. Location of the ion exchange resin in the sample loop of a six-port rotary valve allowed the resin to be regenerated easily and rapidly, with a throughput capability of the order of 50 h⁻¹ and permit the proposed full automation of the whole analytical procedure. In the determination of As in nickel alloy a novel stopped-flow pre-reduction step was developed to permit AsIII quantification, therefore, achieve optimum sensitivity. The two systems permitted limits of detection for Se and As of 2.1 and 3.9 ng ml⁻¹ respectively. Direct comparisons were made with existing matrix isolation systems to emphasise the benefits of system design.

Mercury and its compounds are one of the most toxic global pollutants in the environment. It occurs in all segments of the environment, and it attains the food chain ang human body by people consuming fish. The theoretical part of this thesis examines the characteristics of mercury, its occurrence, the roots of its pollution, and the toxicity of various forms of mercury. Consequently, the thesis delineates analytical methodologies applied to determine the overall level of mercury and chemical forms of mercury. The practical part focuses on monitoring the level of mercury and methylmercury in 12 extracts of fish meat. The analyzer AMA 254 has been used to determine the level of mercury and methylmercury in these extracts. Based on the level that resulted from the measurements, the thesis concludes a risk that correlates with consuming this type of meat.

Theoretical part of the master thesis deals with the occurrence of different mercury species in the environment and describes analytical methods used for determination of mercury in biological samples. In practical part of the master thesis mercury concentration in 14 samples of selected fish and fish product was determined using single purpose absorption spectrometer AMA 254. Measured results were statistically processed and consulted with EU legislative norm.

The presented thesis deals with optimization of parameters speciation analysis based on a selective hydride generation in a direct transfer mode of hydrides and on-line atomization in an atomic absorption spectrometer. In the first part of the thesis processes during generation were investigated. Important indicator of a reactions taking place in a generator is volume of hydrogen (created by decomposition of NaBH4) which is subsequently introduced to the atomizer. In this part of the thesis a new approach to determine a flow rate of hydrogen delivered to the atomizator was developed. An influence of relevant paremeters of the atomizers and atomic absorption spectrometers on basic analytical characteristics of arsenic determination based on hydride generation was performed in the second part. Three atomic absorption spectrometers were used and three sources of radiation were compared. The most important analytic characteristic was the limit of detection which is influenced by standard deviation of measurement values of blank samples and by sensitivity. The best values of the limit of detection were achieved with electrodeless discharge lamps. Key words: hydride generation, arsenic, speciation analysis, atomic absorption spectrometry

This master's thesis deals with optimization of conditions of chemical hydride generation of tellurium and conditions of its atomization, specifically in three types of atomizers - in a diffusion flame (DF), in a heated multiple microflame quartz tube atomizer (MMQTA) and in a dielectric barrier discharge (DBD) atomizer. Tellurium hydride was generated in a flow injection arrangement and a high-resolution continuum source atomic absorption spectrometer was used for detection. As hydride generation can be only done from tetravalent species of tellurium, at first a simple procedure of pre-reduction of hexavalent species of tellurium by heating a standard in hydrochloric acid at 6 mol dm-3 was verified. Further, conditions of chemical generation were optimized with a goal to achieve as high generation efficiency as possible, namely, concentration of hydrochloric acid and sodium tetrahydroborate, volume of the reaction coil and a flow rate of carrier gas. Subsequently, conditions of atomization of tellurium hydride were examined with chosen optimal generation conditions. In the case of DF, it was an amount of hydrogen in the flame, a total flow rate of gases and observation height. In the case of MMQTA, temperature of the atomizer, a flow rate of carrier gas and a flow rate of air or oxygen needed for...

Um procedimento eletroquímico para deposição de paládio no interior de um tubo de grafite para modificação química permanente e um sistema de geração de vapor frio para a determinação de níveis traços de mercúrio em água e sedimento através de espectrometria de absorção atômica é proposto. A célula eletroquímica tubular para as deposições de paládio em fluxo foi construída aproveitando a estrutura original do tubo de grafite o qual opera como eletrodo de trabalho. Um tubo de aço inoxidável, posicionado na saída da célula, é usado como o eletrodo auxiliar. O valor do potencial aplicado no eletrodo de grafite é medido contra um micro eletrodo de referência de Ag/AgCl inserido sobre o eletrodo auxiliar. Soluções de paládio em tampão de acetato (100 milimol L-1, pH=4,70), numa vazão de 0,5 mL min-1 foram usados para executar a deposição eletroquímica durante o intervalo de tempo de 60 min. O sistema de geração de vapor frio consiste de um micro-reator de polietileno e frasco separador líquido-gás, volume total de 4,0 ml, que é descartado depois de cada amostragem para evitar inter-contaminação das amostras. Volumes de 1,0 ml de reagente (2,0% m/v NaBH4 em 0,10 mol L-1 de NaOH) e 1,0 ml de soluções analíticas ou amostras em 0,25 mol L-1 de HNO3 são levados para o reator e separador líquido-gás usando uma bomba peristáltica. O vapor de mercúrio é transportado ao tubo de grafite modificado eletroquimicamente com fluxo de argônio de 212 ml min-1 e pré-concentrado durante 120 s. O limite de detecção obtido foi 93 ng L-1 (n=20, 3&#948;). O desempenho deste sistema foi testado para determinação de mercúrio em água potável, água não potável e sedimentos de lagoa. A confiança de todo procedimento foi confirmada através de testes de recuperação. / An electrochemical procedure for palladium deposition on the inner of a graphite tube for permanent chemical modification and a cold vapor generation system for the determination of trace levels of mercury in water and sediment by atomic absorption spectrometry are proposed. The tubular electrochemical cell for the deposition of palladium was assembled on the original geometry of a graphite tube that operates as the working electrode. A stainless steel tube, positioned downstream from the working electrode, is used as the auxiliary electrode. The potential value applied on the graphite electrode is measured against a micro reference electrode (Ag/AgCl) inserted into the auxiliary electrode. Palladium solutions in acetate buffer (100 milimol L-1, pH=4.70), flowing at 0.5 mL min-1 for 60 min was used to perform the electrochemical deposition. A cold vapor generation system consist of a micro polyethylene reactor and gas-liquid separator flask, total volume of 4.0 mL, that is discarded after each sampling to avoid intercontamination of the samples. Volumes of 1.0 mL of reagent (2.0% m/v NaBH4 in 0.10 mol L-1 of NaOH) and 1.0 mL of reference or sample solutions in 0.25 mol L-1 of HNO3 are carried out to the reactor and gas-liquid separator by using a peristaltic pump. The mercury vapor is transported to the graphite tube electrochemically modified with argon flow (200 mL min-1) and pre-concentrated during 120 s. The detection limit obtained was 93 ng L-1 (n=20, 3&#948;). The performance of these system was tested for determination of mercury in potable and non-potable water and lake sediments. The reliability of the entire procedure was confirmed by recovery tests.

Um procedimento eletroquímico para deposição de paládio no interior de um tubo de grafite para modificação química permanente e um sistema de geração de vapor frio para a determinação de níveis traços de mercúrio em água e sedimento através de espectrometria de absorção atômica é proposto. A célula eletroquímica tubular para as deposições de paládio em fluxo foi construída aproveitando a estrutura original do tubo de grafite o qual opera como eletrodo de trabalho. Um tubo de aço inoxidável, posicionado na saída da célula, é usado como o eletrodo auxiliar. O valor do potencial aplicado no eletrodo de grafite é medido contra um micro eletrodo de referência de Ag/AgCl inserido sobre o eletrodo auxiliar. Soluções de paládio em tampão de acetato (100 milimol L-1, pH=4,70), numa vazão de 0,5 mL min-1 foram usados para executar a deposição eletroquímica durante o intervalo de tempo de 60 min. O sistema de geração de vapor frio consiste de um micro-reator de polietileno e frasco separador líquido-gás, volume total de 4,0 ml, que é descartado depois de cada amostragem para evitar inter-contaminação das amostras. Volumes de 1,0 ml de reagente (2,0% m/v NaBH4 em 0,10 mol L-1 de NaOH) e 1,0 ml de soluções analíticas ou amostras em 0,25 mol L-1 de HNO3 são levados para o reator e separador líquido-gás usando uma bomba peristáltica. O vapor de mercúrio é transportado ao tubo de grafite modificado eletroquimicamente com fluxo de argônio de 212 ml min-1 e pré-concentrado durante 120 s. O limite de detecção obtido foi 93 ng L-1 (n=20, 3&#948;). O desempenho deste sistema foi testado para determinação de mercúrio em água potável, água não potável e sedimentos de lagoa. A confiança de todo procedimento foi confirmada através de testes de recuperação. / An electrochemical procedure for palladium deposition on the inner of a graphite tube for permanent chemical modification and a cold vapor generation system for the determination of trace levels of mercury in water and sediment by atomic absorption spectrometry are proposed. The tubular electrochemical cell for the deposition of palladium was assembled on the original geometry of a graphite tube that operates as the working electrode. A stainless steel tube, positioned downstream from the working electrode, is used as the auxiliary electrode. The potential value applied on the graphite electrode is measured against a micro reference electrode (Ag/AgCl) inserted into the auxiliary electrode. Palladium solutions in acetate buffer (100 milimol L-1, pH=4.70), flowing at 0.5 mL min-1 for 60 min was used to perform the electrochemical deposition. A cold vapor generation system consist of a micro polyethylene reactor and gas-liquid separator flask, total volume of 4.0 mL, that is discarded after each sampling to avoid intercontamination of the samples. Volumes of 1.0 mL of reagent (2.0% m/v NaBH4 in 0.10 mol L-1 of NaOH) and 1.0 mL of reference or sample solutions in 0.25 mol L-1 of HNO3 are carried out to the reactor and gas-liquid separator by using a peristaltic pump. The mercury vapor is transported to the graphite tube electrochemically modified with argon flow (200 mL min-1) and pre-concentrated during 120 s. The detection limit obtained was 93 ng L-1 (n=20, 3&#948;). The performance of these system was tested for determination of mercury in potable and non-potable water and lake sediments. The reliability of the entire procedure was confirmed by recovery tests.

The main goal of the work presented in this thesis is to improve the reliability of existing methods for speciation analysis of organotin compounds Species-specific isotope dilution (SSID) calibration in combination with gas chromatography – inductively coupled plasma mass spectrometry was used to investigate the transformation of phenyltin species during sample preparation. Isotope-enriched phenyltin species were synthesized from corresponding isotope-enriched tin metals. SSID with a mixture of phenyltin species (PhTs) from one isotope was used to evaluate different extraction procedures for the determination of PhTs in fresh water sediment. Preparative liquid chromatography was used to produce single isotope-enriched phenyltin species making a multi-isotope spike (MI) SSID calibration possible. Different extraction procedures for the analysis of phenyltin species in biological samples were evaluated by applying MI-SSID. Degradation of TPhT and DPhT during sample extraction was observed and quantified. Accurate results were therefore obtained. A sample preparation procedure using mild extraction conditions with reasonable recoveries is described. The stability of organotin standards was investigated under different storage conditions. Mono- and diphenyltin were found to be redistributed and degraded during storage in methanol but were stabilized in sodium acetate/ acetic acid. A fast redistribution between monobutyl- and diphenyl tin has been observed and therefore it is therefore recommended that standards be derivatized as soon as possible after butyl- and phenyltin standards are mixed. Included in the thesis is also an investigation of the analytical potential of using instrumentation based on atomic absorption spectrometry (AAS) for speciation analysis of organotin compounds. The method was based on gas chromatographic separation, atomization in a quartz tube and detection by line source (LS) AAS and for comparison, by state of the art continuum source (CS) AAS. Analytical performances of CSAAS system were found to be better compared to LSAAS.