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Advisor(s)
Abstract(s)
A Diretiva Quadro de Água é o principal diploma legislativo da União Europeia
relativo a água cujo objetivo fundamental é conservar e melhorar o ambiente aquático dos
Estados Membro. O diploma tem como objetivo preservar a qualidade de águas, proteger e
melhorar ecossistemas aquáticos e terrestres sobre as necessidades de água.
O presente trabalho foi realizado no Laboratório de Referência do Ambiente (LRA) da
Agência Portuguesa do Ambiente (APA, I.P.), setor da Química Geral com o objetivo de
validar métodos fotométricos de análise em cuvetes Hach Lange para as determinações de
CQO, fluoretos e sulfuretos em amostras de águas pelo facto destes testes permitirem obter
resultados fiáveis, com manuseamento simples, rápido e seguro.
Avaliou-se a linearidade do método para CQO, fluoretos e sulfuretos com valores de
coeficiente de correlação superiores a 0,995. Os limites de deteção e de quantificação foram
determinados a partir das curvas de calibração cujos valores para CQO foram 3,97 e 11,90
mg/L O2 (padrão Hach) e 4,37 e 13,12mg/L O2 (padrão laboratório), respetivamente. A
precisão foi determinada através de ensaios de repetibilidade e reprodutibilidade, obtendo-se
valores de CV inferiores a 5%. A exatidão do método CQO foi avaliada com base nos
resultados dos ensaios interlaboratoriais cujos valores de z-score cumpriram o critério de
aceitação (-3 <z-score <3).
Os fluoretos foram determinados em amostras de águas naturais e os resultados
comparados com a legislação em vigor. Não foi efectuada a quantificação de sulfuretos em
amostras devido a ausência deste analito nas águas analisadas no LRA.
Em conclusão, os resultados alcançados nos procedimentos de validação são
comparáveis aos do LRA, tendo sido possível reduzir, significativamente, a quantidade de
reagentes utilizados, diminuindo custos de análise, contribuindo para gestão mais sustentável
de resíduos e reduzindo impactes ambientais que estão associados ao método tradicional.
The Water Framework Directive is the European Union's main legislative document on water, whose fundamental objective is to conserve and improve the aquatic environment of Member States. This legislation aims to preserve water quality, protect and improve aquatic and terrestrial ecosystems over water needs. This work was carried out at the Laboratório de Referência do Ambiente (LRA) of the Agência Portuguesa do Ambiente (APA, I.P.), in the General Chemistry sector in order to validate analytical photometric methods in Hach Lange cuvettes for determination of COD, fluoride and sulphide in water samples because this tests provide reliable and accurate results with simple, fast and safe handling. Linearity for COD, fluorides and sulphides was evaluated by correlation coefficient (r) which values were greater than 0.995. The limits of detection and quantification were determined from the calibration curves whose values were for COD 3.97 and 11.90mg/ L O2 (Hach standard) and 4.37 and 13.12 mg / L O2 (laboratory standard), respectively. The precision of the methods was determined through repeatability and reproducibility tests with CV values below 5%. The accuracy of the COD method was assessed based on the results of interlaboratory tests whose z-score values met the acceptance criteria (-3 <z-score <3). Fluorides were determined in natural water samples and the results compared to current legislation. Quantification of sulfides in samples was not performed due to the absence of this analyte in the waters analyzed in the LRA. In conclusion, the results achieved in the validation procedures are comparable to those of the LRA, making possible to significantly reduce the amount of reagents and decrease analysis costs, contributing to a best sustainable waste management and to the reduction of the environmental impacts associated with the traditional method.
The Water Framework Directive is the European Union's main legislative document on water, whose fundamental objective is to conserve and improve the aquatic environment of Member States. This legislation aims to preserve water quality, protect and improve aquatic and terrestrial ecosystems over water needs. This work was carried out at the Laboratório de Referência do Ambiente (LRA) of the Agência Portuguesa do Ambiente (APA, I.P.), in the General Chemistry sector in order to validate analytical photometric methods in Hach Lange cuvettes for determination of COD, fluoride and sulphide in water samples because this tests provide reliable and accurate results with simple, fast and safe handling. Linearity for COD, fluorides and sulphides was evaluated by correlation coefficient (r) which values were greater than 0.995. The limits of detection and quantification were determined from the calibration curves whose values were for COD 3.97 and 11.90mg/ L O2 (Hach standard) and 4.37 and 13.12 mg / L O2 (laboratory standard), respectively. The precision of the methods was determined through repeatability and reproducibility tests with CV values below 5%. The accuracy of the COD method was assessed based on the results of interlaboratory tests whose z-score values met the acceptance criteria (-3 <z-score <3). Fluorides were determined in natural water samples and the results compared to current legislation. Quantification of sulfides in samples was not performed due to the absence of this analyte in the waters analyzed in the LRA. In conclusion, the results achieved in the validation procedures are comparable to those of the LRA, making possible to significantly reduce the amount of reagents and decrease analysis costs, contributing to a best sustainable waste management and to the reduction of the environmental impacts associated with the traditional method.
Description
Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia da Qualidade e Ambiente
Keywords
CQO COD Sulfuretos Sulphides Fluoretos Fluorides Validação Validation Cuvetes Hach Lange Hach Lange cuvettes
Citation
QUETA, Hans - Caraterização físico-química de amostras no âmbito da diretiva quadro da água. Lisboa: Instituto Superior de Engenharia de Lisboa, 2018. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa