by Kwan Hok-wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 67-69). / Abstracts in English and Chinese. / Acknowledgment --- p.i / Abstract --- p.ii / Chapter 1. --- INTRODUCTION / Chapter 1.1 --- Chemical speciation of cyanide --- p.1 / Chapter 1.2 --- Review of analytical techniques for cyanide determination --- p.3 / Chapter 1.3 --- Importance of sediment in the environment --- p.6 / Chapter 1.4 --- Characteristics of marine sediment --- p.6 / Chapter 1.5 --- Antropogenic sources of cyanide --- p.7 / Chapter 1.6 --- Research objective --- p.8 / Chapter 1.7 --- Brief description of the project --- p.9 / Chapter 2. --- INSTRUMENTATION AND THEORY / Chapter 2.1 --- Instrumentation for flow injection analysis system --- p.11 / Chapter 2.2 --- Basic principles of flow injection analysis --- p.21 / Chapter 2.3 --- Basic principles of amperometric detection --- p.24 / Chapter 3. --- EXPERIMENTAL / Chapter 3.1 --- Instrumentation --- p.25 / Chapter 3.2 --- Reagents --- p.32 / Chapter 3.3 --- Sample preparation --- p.34 / Chapter 4. --- RESULTS AND DISCUSSION / Chapter 4.1 --- Effect of bismuth on on-line precipitation of sulphide in FIA --- p.37 / Chapter 4.2 --- Calibration --- p.37 / Chapter 4.3 --- Effectiveness of the distillation conditions --- p.41 / Chapter 4.4 --- Comparisons of cyanide extraction methods for sediment analysis --- p.42 / Chapter 4.5 --- Effect of bismuth nitrate on cyanide recoveries --- p.45 / Chapter 4.6 --- Effect of bismuth nitrate on cyanide recoveries in the presence of sulphide --- p.48 / Chapter 4.7 --- Effect of bismuth nitrate on recoveries of total cyanide in the analysis of interlaboratory test samples --- p.55 / Chapter 4.8 --- Recoveries of complexed cyanide in the analysis of SETOC sample with sulphide interference --- p.57 / Chapter 4.9 --- Analysis of marine sediment samples --- p.58 / Chapter 4.10 --- Recovery tests and precision studies --- p.59 / Chapter 4.11 --- Interferences --- p.62 / Chapter 5. --- CONCLUSION --- p.66 / Chapter 6. --- REFERENCES --- p.67

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed March 26, 2009)

Orientador: Maria del Pilar Taboada Sotomayor / Banca: Marco Aurelio Cebim / Banca: Mariele Mucio Pedroso / Banca: Bruno Campos Janegitz / Banca: Renata Kelly Mendes Valente / Resumo: O presente estudo está baseado na construção de sensores biomiméticos para determinação sensível e seletiva de dois poluentes, o íon cianeto, que é liberado no ambiente por meio de efluentes da indústria metalúrgica; e o composto 3,4-dicloroanilina, o metabólito do herbicida diuron que causa alteração do sistema endócrino, largamente usado na agricultura. Para o desenvolvimento dos sensores biomiméticos, eletrodos à base de pasta de carbono foram modificados com complexos que mimetizam o sítio ativo das enzimas P450. Os complexos que apresentaram perfil biomimético e melhores resultados na determinação voltamétrica do íon cianeto e do 3,4-dicloranilina, foram respectivamente 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H, 31H-ftalocianincacobalto (II) [Co(II)PcF16] e ftalocianinacobre (II) [Cu(II)Pc]. O sensor construído para a determinação do íon cianeto apresentou as melhores respostas utilizando como eletrólito de suporte o hidróxido de sódio 0,5 mol L-1 pH 12,0 e 15% m/m do complexo [Co(II)PcF16], usando a voltametria de onda quadrada a 20 Hz de frequência, 10 mV de amplitude e 10 mV de incremento de potencial. Com os parâmetros otimizados, o sensor apresentou uma faixa linear de resposta de 2,4 x 10-5 mol L-1 a 1,7 x 10-4 mol L-1 e limites de detecção e de quantificação de 1,1 x 10-5 mol L-1 e 3,6 x 10-5 mol L-1, respectivamente. Os melhores resultados obtidos para o sensor desenvolvido para o herbicida 3,4-dicloroanilina foram em solução tampão Britton-Rob... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study is based on the construction of biomimetic sensors for the sensitive and selective determination of two pollutants, the cyanide ion, which is released into the environment through effluents from the metallurgical industry and 3,4-dichloroaniline, the metabolite of the herbicide diuron that causes alteration of the endocrine system, widely used in agriculture. For the development of biomimetic sensors, carbon paste-based electrodes have been modified with complexes that mimic the active site of the P450 enzymes. The complexes that presented biomimetic profile and better analytical performance in the voltammetric determination of cyanide and 3,4-dichloraniline were respectively 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanincobalt (II) [Co(II)PcF16] and phthalocyaninecopper (II) [Cu(II)Pc]. The sensor constructed for the determination of the cyanide ion presented the best responses using sodium hydroxide 0.5 mol L-1 pH 12.0 and 15% w/w of the [Co(II)PcF16] complex as the support electrolyte, using square wave voltammetry at 20 Hz frequency, 10 mV amplitude and 10 mV potential increase (ΔEs). With the optimized parameters, the sensor had a linear response range of 2.4 x 10-5 mol L-1 to 1.7 x 10-4 mol L-1 and limits of detection and quantification of 1,1 x 10-5mol L-1 and 3,6 x 10-5 mol L-1, respectively. The best results for the 3,4-dichloroaniline herbicide were obtained in Britton-Robinson 0.1 mol L-1 pH 5.0 buffer and 15% w/w [Cu(II)Pc] using square wave voltammetry at 30 Hz frequency, 100 mV amplitude and 5 mV potential increase (ΔEs). Under optimized conditions, the sensor presented a linear response range of 2.8 x 10-5 to 3.0 x 10-4 mol L-1 and limits of detection and quantification of 1,1 x 10-5 mol L-1 and 3,7 x 10-5 mol L-1, respectively. The biomimeticity of the sensors were also evaluated, exploring the hyperbolic profile of each response... / Doutor

Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 2000 / Cyanide is used extensively in the mining industry to leach gold and silver from their ores. Cyanide, in the form of sodium or potassium cyanide, is added in excess to that required theoretically due to equilibrium and kinetic considerations in the leaching step. This results in free cyanide and various other cyanide complexes reporting to the effluent streams of these operations In this study the removal of these species from solution by means of ion exchange resins was investigated Equilibrium conditions, kinetic parameters and the competitive exchange nature of the process was evaluated. The experimental work focused on contacting the various resins individually in a batch reactor with free cyanide, Iron cyanide and copper cyanide complexes. The experimental data obtained was found to be well explained by the Freundlich-type multiand single-component isotherms. Furthermore, mass transfer parameters were investigated revealing that ceI1ain cyanide species outperform others kinetically in the ion exchange process. During this study it was shown that ion exchange processes could be effective in effluent clean-up of those streams containing cyanide complexes

Orientador: Angelo Zanaga Trape / Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T15:47:56Z (GMT). No. of bitstreams: 1 Figueiredo_VanessaCatherinaNeumann_D.pdf: 4421936 bytes, checksum: 977aefceaac1c12fc11f98a25b94ef2d (MD5) Previous issue date: 2008 / Resumo: Esta pesquisa de corte transversal procurou verificar as condições de saúde de trabalhadoras inseridas no processo produtivo de bijuterias e folheados de Limeira, SP. Para isso, traçou-se um perfil acerca do trabalho realizado, exposição ao cianeto e queixas de saúde auto-referidas, comparando um grupo de 191 trabalhadoras inseridas em empresas com processo de galvanoplastia (expostas ao cianeto) e um grupo de 192 trabalhadoras inseridas em empresas que fabricam e montam peças brutas (não expostas ao cianeto). Foi aplicado um questionário para levantamento de informações sócio-demográficas, familiares e funcionais, além do Índice de Capacidade para o Trabalho, a Escala de Estresse no Trabalho, o SRQ-20, o SF-36, o Audit e a Escala de Tolerância de Fagerström. No geral, 44,4% das trabalhadoras são solteiras, 54,3% têm entre 20 e 29 anos, 49,9% são brancas, 62,9% têm ensino médio completo, 55,4% não têm filhos, 40,7% afirmaram ter alguma lesão ou doença confirmada por médico e o Estado de Saúde (SF36) teve uma média de 66,9. As questões relacionadas a favoritismo e discriminação dentro de ambiente e a pouca perspectiva de crescimento são os fatores psicossociais mais estressantes para essa população, sendo que 14,8% apresentaram classificação positiva para transtornos mentais comuns (SRQ-20), com dores de cabeça freqüentes. Sobre o estilo de vida, 93,7% apresentaram baixo risco de dependência alcoólica (Audit), e 65,5% nunca fumaram. Sobre o trabalho, 59% não usam EPI, 68,4% ocupam o cargo de Auxiliar de Ourives, e entre as trabalhadoras inseridas no processo de tratamento de superfície 48,9% lidam diretamente com cianeto. Na comparação entre os grupos foi encontrada uma diferença estatisticamente significante com relação ao número de lesões e doenças referidas confirmadas por avaliação médica (ICT), sendo que o grupo exposto apresentou menos lesões que o grupo não exposto ao cianeto (p=0,042), e o grupo exposto apresentou diferenças com relação à prevalência de distúrbios de tireóide (p=0,022), bronquite crônica (p=0,027) e sinusite crônica (p=0,022), enquanto que o grupo não exposto apresentou maior prevalência de lesões nos braços e nas mãos (p <0,001). Os distúrbios de tireóide foram associados a um maior tempo de trabalho no setor (p=0,035), a uma menor pontuação no índice de capacidade para o trabalho (p=0,001), maior freqüência de distúrbios emocionais menores (p=0,006), a um cansaço constante (p=0,001) e facilidade de se cansar (p<0,001), menor pontuação na capacidade funcional (p=0,021), na vitalidade (p=0,001), nos aspectos emocionais (p=0,010), e no domínio saúde mental (p=0,011). A lesão nos braços e nas mãos não foi associada à responsabilidade de limpar a casa (p=0,114) nem à responsabilidade de passar roupa (p=0,252). Foi encontrado um perfil de adoecimento diferente para cada grupo pesquisado, sendo que o grupo de trabalhadoras não expostas ao cianeto apresentou pior condição de saúde / Abstract: The objective of this transversal cut research was to check the health conditions of women working in the gold platted- and fashion jewel manufacture in Limeira, SP, Brazil. To do so, a profile of the subjects was designed taking into account the tasks performed by the workers, their exposure to cyanide and the self-referred complaints of health problems. A group of 191 labourers working in companies using galvanoplastic processes (exposed to cyanide) was compared with 192 workers placed in companies that manufacture and assemble manufactured parts (not exposed to cyanide). Socio-demographic, family and functional information, in addition of the Work Index Capacity, the Stress at Work Index, SRQ-20, SF-36, Audit, and the Fagerström Scale of Tolerance, were obtained by applying a questionnaire. Overall, 44.4% of the workers were single, 54.3% were between 20 and 29 years old, 49.9% are white, 62.9% completed high school, 55.4% have no children, 40.7% said declared having had injuries or illness, as confirmed by a physician, and the mean of the State of Health (SF36) was 66.9. The facts related to discrimination and favouritism in the working environment, as well as the low expectation of progress are the main psychosocial stressing factors for this population, so that 14.8% had a positive rating for common mental disorders (SRQ-20) involving frequent headaches. Related to the lifestyle, 93.7% had low risk of alcohol dependence (Audit), and 65.5% never smoked. In their work, 59% do not use EPI, 68.4% occupy the post of Jeweler Assistant, and among the workers involved with surface treatment 48.9% deal directly with cyanide. The comparison between both groups showed a statistically significant difference in the number of referred injuries and diseases as confirmed by medical evaluation. The group exposed to cyanide presented less injuries than the not exposed group (p=0.042). Thyroid disorders (p=0.022), chronic bronchitis (p=0.027), and chronic sinusitis (p=0.022) prevailed in the exposed group, whereas a prevalence of injuries in the arms and hands (p <0.001) was found in the not exposed group. Thyroid disturbances were associated with longer working times in the industry (p=0.035), lower scores of the work capacity index (p=0.001), increased frequency of minor psychiatric disorders (p=0.006), continuous fatigue (p=0.001) and ease of getting tired (p<0.001), lower functional capacity scores (p=0.021), vitality (p=0.001), emotional aspects (p=0.010), and in the mental health domain (p=0.011). Damage in arms and hands were not associated with domestic labour like house cleaning (p=0.114) or ironing (p=0.252). These issues should be accounted for in studies aiming to establish the specific characteristics of each occupation when determining the ailing process of these workers. The research found a profile of illness different for each group searched, and that the group of workers not exposed to cyanide showed worse health condition / Doutorado / Epidemiologia / Doutor em Saude Coletiva

Cyanide utilization in Pseudomonas fluorescens NCIMB 11764 occurs via oxidative conversion to carbon dioxide and ammonia, the latter satisfying the nitrogen requirement. Substrate attack is initiated by an enzyme referred to as cyanide oxygenase (CNO), previously shown to require components in both high (H) (>30 kDa) and low (L) (<10 kDa) molecular weight cell fractions. In this study, tetrahydrobiopterin (H4biopterin) was identified as a cofactor in fraction L, thus making CNO appear as a pterin- dependent hydroxylase. CNO was purified 150-fold (specific activity 0.9 U/mg) and quantitatively converted cyanide to formate and ammonia as reaction products. When coupled with formate dehydrogenase, the complete enzymatic system for cyanide oxidation to carbon dioxide and ammonia was reconstituted. CNO was found to be an aggregate of known enzymes that included NADH oxidase (Nox), NADH peroxidase (Npx), cyanide dihydratase (CynD) and carbonic anhydrase (CA). A complex multi-step reaction mechanism is proposed in which Nox generates hydrogen peroxide which in turn is utilized by Npx to catalyze the oxygenation of cyanide to formamide accompanied by the consumption of one and two molar equivalents of oxygen and NADH, respectively. The further hydrolysis of formamide to ammonia and formate is thought to be mediated by CynD. The role of H4biopterin and of the enzyme CA in the proposed process remains unclear, but the involvement of each in reactive oxygen and radical chemistry is consistent with the proposed formation of such species in the catalytic process. H4biopterin may additionally serve as a protein stabilizing agent along with a protein co-purifying with CynD identified as elongation factor Tu, a known chaperone. At least two of the CNO components (Nox and CynD) are complex oligomeric proteins whose apparent association with Npx and CA appears to be favored in bacterial cells induced with cyanide allowing their purification in toto as a multiprotein enzyme complex.

Cell-free extracts from Pseudomonas fluorescens NCIMB 11764 catalyzed the degradation of cyanide into products that included C02, formic acid, formamide and ammonia. Cyanide-degrading activity was localized to cytosolic cell fractions and was observed at substrate concentrations as high as 100 mM. Two cyanide degrading activities were identified by: (i) the determination of reaction products stoichiometries, (ii) requirements for NADH and oxygen, and (iii) kinetic analysis. The first activity produced CO2 and NH3 as reaction products, was dependent on oxygen and NADH for activity, and displayed an apparent Km for cyanide of 1.2 mM. The second activity generated formic acid (and NH3) pfus formamide as reaction products, was oxygen independent, and had an apparent Km of 12 mM for cyanide. The first enzymatic activity was identified as cyanide oxygenase whereas the second activity consists of two enzymes, a cyanide nitrilase (dihydratase) and putative cyanide hydratase. In addition to these enzymes, cyanide-grown cells were also induced for formate dehydrogenase (FDH), providing a means of recycling NADH utilized by cyanide oxygenase.

ΔH values for the formation of Ni(CN)4(aq)= have been determined calorimetrically at 25° using a simple calorimeter and a thermometric titration procedure at high and low ionic strengths, respectively. Extrapolation of these ΔH values to infinite dilution resulted in a ΔH° value of -42.7 kcal./mole. Combination of ΔH° and ΔF° values gives a ΔS° value of -5.5 e.u. for Ni(CN)4(aq)= formation. A value of +70 e.u. is calculated for the ionic entropy of Ni(CN)4(aq)=. A preliminary investigation of the Zn(CN)4(aq)= system indicated the existence of zinc cyanide complexes other than Zn(CN)4= and allowed calculation of an approximate ΔH° value of -26.5 kcal./mole for the heat of formation of Zn(CN)4(aq)= at 25° and infinite dilution. The heats of neutralization of perchloric and hydrochloric acids with sodium hydroxide have been determined using a non-isothermal, constant-temperature-environment solution calorimeter. The final concentration of the solutions studied varied from 5.0 x 10-3 to 3.5 x 10-2 M. A value of +13.337 ± 0.015 kcal./mole for the heat of ionization of water at infinite dilution was calculated both by extrapolation of the data to infinite dilution and by correction of the data to infinite dilution using the appropriate heat of dilution data. ΔH° and ΔS° values have been determined for the stepwise reaction at 8, 25, and 40° of X- (X = Cl, Br, I) with Hg++ to form HgX2 (aq) and HgX2 (s) (X = I). All data are valid in a solvent 0.10 Fin HClO4 and 0.40F in NaClO4 Relative Hg-X bond strengths in the gaseous pnase and in aqueous solution are discussed. Trends in ΔH° and ΔS° values are discussed in terms of the thermodynamic quantities involved.

Pseudomonas fluorescens NCIMB 11764 (Pf11764) is uniquely able to grow on the poison cyanide as its sole nitrogen source. It does so by converting cyanide oxidatively to carbon dioxide and ammonia, the latter being assimilated into cellular molecules. This requires a complex enzymatic machinery that includes nitrilase and oxygenase enzymes the nature of which are not well understood. In the course of a proteomics analysis aimed at achieving a better understanding of the proteins that may be required for cyanide degradation by Pf11764, an unknown protein of 17.8 kDa was detected in cells exposed to cyanide. Analysis of this protein by ESI-coupled mass spectrometry and bioinformatics searches gave evidence of strong homology with a protein (Hyp1) of unknown function (hypothetical) present in the bacterium Photorhabdus luminescens subsp. laumondii TTO1 (locus plu_1232). A search of available microbial genomes revealed a number of Hyp1 orthologs the genes of which are found in a conserved gene cluster known as Nit1C. Independent studies revealed that in addition to Hyp1, Pf11764 possesses a gene (nit) specifying a nitrilase enzyme whose closest homologue is a nitrilase found in Nit1C gene clusters (77% amino acid identity). DNA sequence analysis has further revealed that indeed, hyp1Pf11764 and nitPf11764 are contained in a cluster that includes also a gene specifying an oxygenase. Given the possible connection of Nit1C-endoded nitrilase and oxygenase enzymes to enzymatic cyanide degradation, there is strong reason for thinking that the genes specifying these enzymes contribute to bacterial growth on cyanide in those bacteria containing the Nit1C cluster. Because the biological function of the Hyp1 protein is currently unknown, it was cloned and the protein expressed in E. coli so that its properties could further be explored. Unfortunately, the expression of the protein in an insoluble form complicated these analyses. However, at least two lines of evidence suggest a possible role as a regulator of gene expression. First, over-expression of the protein was accompanied by the parallel elevation of the putative vector-encoded b-lactamase, implying that Hyp1Pf11764 can affect the expression of other genes. Second, a comparison of the amino acid sequence of select peptide fragments of Hyp1Pf11764, by conducting searches for homology with proteins in the existing nonredundant protein database, consistently revealed motifs in common with those present in bacterial response regulators that are part of two-component signal transduction systems widely distributed in bacteria.

The involvement of cyanide oxygenase in the metabolism of pyruvate and a-ketoglutarate-cyanohydrin was investigated and shown to occur indirectly by the consumption of free cyanide arising from the cyanohydrins via chemical dissociation. Thus, free cyanide remains the substrate, for which the enzyme displays a remarkably high affinity (Kmapp,4 mM). A model for cyanide utilization is therefore envisioned in which the substrate is initially detoxified by complexation to an appropriate ligand followed by enzymatic oxidation of cyanide arising at sublethal levels via chemical dissociation. Putative cyanide oxygenase in cell extracts consumed both oxygen and NADH in equimolar proportions during cyanide conversion to CO2 and NH3 and existed separately from an unknown heat-stable species responsible for the nonenzymatic cyanide-catalyzed consumption of oxygen. Evidence of cyanide inhibition and nonlinear kinetics between enzyme activity and protein concentration point to a complex mechanism of enzymatic substrate conversion.