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Estudo da estabilidade de agentes de contraste de gadolíneo em diferentes condições ambientais estuarinas
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Resumo(s)
Os agentes de contraste de gadolínio (AC-Gd) são poliaminocarboxilatos ligados a um
ião Gd3+ que se encontra no centro do complexo e é altamente tóxico para o ser humano
quando presente na sua forma iónica. Estes complexos são utilizados em exames médicos de
ressonância magnética, sendo administrados nos pacientes por via intravenosa, e
posteriormente eliminados por via renal, passando pelas estações de tratamento de águas
residuais (ETAR) antes de serem descartados no meio recetor, sem eliminação aparente. Os
AC-Gd são conhecidos pela sua elevada estabilidade in vivo, mas desconhece-se se esta
estabilidade se mantém quando libertados para o meio ambiente. Neste trabalho, verificou -se
se diferentes períodos de exposição a determinados parâmetros ambientais, como a radiação
solar e diferentes valores de salinidade, temperatura e pH, vão de alguma maneira influenciar
a estabilidade destes complexos, nomeadamente, do complexo utilizado neste estudo, o GdDOTA. Dos resultados obtidos, não se verificou qualquer degradação aparente do complexo
quando exposto às temperaturas de 15 °C e 40 °C durante períodos entre 24 h e 96 h,
independentemente da salinidade do meio estudado (0 PSU, 18 PSU e 36 PSU). No entanto,
verificou-se que ocorreu uma crescente degradação do complexo ao longo do tempo quando
exposto a pH ácidos (pH 2), sendo esta mais acentuada na salinidade de 0 PSU. Relativamente
à exposição à radiação solar, verificou-se que ocorreu alguma degradação ao fim de 24 h para
a salinidade de 18 PSU, mas a quantidade de Gd livre (Gd3+) manteve-se constante no decorrer
do resto da experiência.
Gadolinium-based contrast agents (Gd-CA) are polyaminocarboxylates linked to a Gd3+ ion that is found at the center of the complex and is highly toxic to humans when in its ionic form. These complexes are used in Magnetic Resonance Imaging (MRI), being administered in patients intravenously, and then eliminated via renal, passing through wastewater treatment plants (WWTP) before being discarded in the receiving medium, without apparent removal. Gd-CA are known for their high stability in vivo, but it is unknown if this stability is maintained when released into the environment. In this study, it was studied if different exposure periods to several environmental parameters, such as solar radiation, different salinities, temperatures and pH values will, in some way, influence the stability of these complexes, namely, the complex used in this study, Gd-DOTA. From the results obtained, there was no apparent degradation of the complex when exposed to temperatures of 15 °C and 40 °C for periods between 24 h and 96 h, regardless the salinity of the studied medium (0 PSU, 18 PSU and 36 PSU). However, it was found an increased complex degradation over time when exposed to acidic pH (pH 2), which was more pronounced at salinity 0 PSU. Regarding the exposure to solar radiation, it was found that some degradation occurs after 24 h at salinity 18 PSU, but the amount of free Gd (Gd3+) remained constant throughout the rest of the experiment.
Gadolinium-based contrast agents (Gd-CA) are polyaminocarboxylates linked to a Gd3+ ion that is found at the center of the complex and is highly toxic to humans when in its ionic form. These complexes are used in Magnetic Resonance Imaging (MRI), being administered in patients intravenously, and then eliminated via renal, passing through wastewater treatment plants (WWTP) before being discarded in the receiving medium, without apparent removal. Gd-CA are known for their high stability in vivo, but it is unknown if this stability is maintained when released into the environment. In this study, it was studied if different exposure periods to several environmental parameters, such as solar radiation, different salinities, temperatures and pH values will, in some way, influence the stability of these complexes, namely, the complex used in this study, Gd-DOTA. From the results obtained, there was no apparent degradation of the complex when exposed to temperatures of 15 °C and 40 °C for periods between 24 h and 96 h, regardless the salinity of the studied medium (0 PSU, 18 PSU and 36 PSU). However, it was found an increased complex degradation over time when exposed to acidic pH (pH 2), which was more pronounced at salinity 0 PSU. Regarding the exposure to solar radiation, it was found that some degradation occurs after 24 h at salinity 18 PSU, but the amount of free Gd (Gd3+) remained constant throughout the rest of the experiment.
Descrição
Relatório de Estágio de Mestrado, Química Tecnológica, 2022, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Gadolínio Agente de contraste ICP-MS Estabilidade química Teses de mestrado - 2023