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Percorrer por autor "Nemoto, Ana Carolina Mallasen"

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  • Monitoring of anti-inflammatory drugs in hydric media from Bragança district
    Publication . Nemoto, Ana Carolina Mallasen; Queiroz, Ana; Ribeiro, António E.; Brito, Paulo; Gonçalves, Morgana Suszek
    Emerging micropollutants are chemical substances present in different matrices at very low concentrations, ranging from nanograms to micrograms per liter. Non-Steroidal Anti-Inflammatory Drugs (NSAID) are some of the most prescribed drugs worldwide and several studies report the presence of these substances in various hydric media including drinking water, surface water, and sewage water, among others. Since they are present in very low concentrations, their identification, quantification and removal are not easy tasks. The main objective of this work is to gather some knowledge about the most recent analytical methodologies in the field, in order to start the evaluation of this environmental and health problem in the Bragança region. Therefore, this work is based on the development of an analytical methodology to extract, detect and quantify non-steroidal anti-inflammatory drugs and on the validation of this methodology using real samples from different hydric media of the Bragança region. From an initial set of ten pharmaceutical drugs belonging to different pharmacological classes, a group of five NSAID, acetyl salicylic acid, diclofenac, ibuprofen, ketoprofen and naproxen, was selected as the prototype acidic molecules due to their relatively low pKa (3.49 to 4.91). After an extensive literature review, the solid phase extraction (SPE) was selected as extraction technique using an adsorbent (Chromabond® HLB) applicable for a wide range of analyte polarities. In order to improve the SPE recoveries, several experimental measurements were performed using different flow-rates for the adsorbent conditioning, sample loading, washing and elution steps. Extractions were performed with individual and mixture standards prepared in ultrapure water with the aim of evaluating the analytes recovery. The high performance liquid chromatography with photo diode array detector (HPLC-DAD) was the selected instrumental method of analysis with a Nucleosil C18 column under reversed phase mode conditions. Several studies were carried out to optimize the mobile phase composition, mobile phase pH, elution flow-rate and wavelengths for detector monitorization. After the optimization of some SPE/HPLC-DAD operating conditions, the developed methodology was validated analyzing six real samples collected from different aqueous sources in Bragança region: city tap water, well water, swimming pool, “river A” at two different points and “river B”. The river A, location 1, was contaminated with naproxen and ketoprofen and the well water sample indicated the presence of ketoprofen. For these samples, taking into account the limits of quantification (LOQ) of the developed analytical method, only river A contamination could be evaluated with a measured concentration of 11.230 ± 0.767 ppb for ketoprofen. The concentrations of naproxen in river A and ketoprofen in well water sample were below the LOQ but above the limit of detection (LOD), proving the presence of these compounds. Responses were also observed for acetyl salicylic acid in river A, location 1, and in pool water samples, but their values were below the LOD, therefore, it is not possible to confirm the presence of this NSAID in those samples.
    2019Dissertação de mestrado Acesso aberto Ver mais