Development of a simple analytical method for the simultaneousdetermination of paracetamol, paracetamol-glucuronide andp-aminophenol in river water

Paracetamol is among the most worldwide consumed pharmaceuticals. Although its occurrence in the environment is well documented, data about the presence of its metabolites and transformation products is very scarce. The present work describes the development of an analytical method for the simultaneous determination of paracetamol, its principal metabolite (paracetamol-glucuronide) and its main transformation product (p-aminophenol) based on solid phase extraction (SPE) and high performance liquid chromatography coupled to diode array detection (HPLC-DAD). The method was applied to analysis of river waters, showing to be suitable to be used in routine analysis. Different SPE sorbents were compared and the use of two Oasis WAX cartridges in tandem proved to be the most adequate approach for sample clean up and pre-concentration. Under optimized conditions, limits of detection in the range 40–67 ng/L were obtained, as well as mean recoveries between 60 and 110% with relative standard deviations (RSD) below 6%. Finally, the developed SPE-HPLC/DAD method was successfully applied to the analysis of the selected compounds in samples from seven rivers located in the north of Portugal. Nevertheless all the compounds were detected, it was the first time that paracetamol-glucuronide was found in river water at concentrations up to 3.57 μg/L.

Desenvolvimento de Métodos de Extração de Resíduos de Antimicrobianos e Quantificação em Amostras Alimentares

O leite é um alimento complexo, pela sua composição rico em água, proteínas, lípidos, vitaminas e minerais. Devido ao seu alto valor nutricional é fundamental para a amamentação de crianças e animais em crescimento, pois fornece componentes fundamentais para o desenvolvimento e manutenção da saúde. Os antimicrobianos são amplamente utilizados como uma medida terapêutica no tratamento de infeções bacterianas, profilaxia e como promotores de crescimento (aditivos). A presença de resíduos de antimicrobianos no leite pode representar riscos para a saúde humana, como reações alérgicas em indivíduos hipersensíveis e resistências. Os objetivos deste estudo são o desenvolvimento de novos métodos de limpeza e de pré-concentração para amostras de leite, por meio de extração em fase sólida (SPE), com a finalidade de realizar uma melhor identificação e quantificação de antimicrobiana por Cromatografia Líquida de Alta Performance (HPLC). Todos os métodos desenvolvidos são de fácil execução, com taxas de recuperação dos agentes antimicrobianos viáveis, com uma percentagem de recuperação a partir de 85%. O método cromatográfico utilizado para a deteção e quantificação (HPLC-DAD) têm os limites de deteção (LD) entre 2.43ng / mL e 1.62ng / mL e os limites de quantificação (LQ) entre 7,36 ng / mL e 4.92 ng / mL, o que significa este método vai de encontro às diretrizes estipuladas pela União Europeia para os agentes antimicrobianos estudados. A combinação dos métodos propostos de limpeza e pré-concentração por SPE e multirresíduo por HPLC-DAD permite, por conseguinte, a deteção e quantificação de resíduos de antibióticos no leite, tornando esta uma alternativa importante e útil no processo de controlo de qualidade para a indústria de alimentos e outras área.

Effects of early life permethrin exposure on spatial working memory and on monoamine levels in different brain areas of pre-senescent rats

Pesticide exposure during brain development could represent an important risk factor for the onset of neurodegenerative diseases. Previous studies investigated the effect of permethrin (PERM) administered at 34 mg/kg, a dose close to the no observable adverse effect level (NOAEL) from post natal day (PND) 6 to PND 21 in rats. Despite the PERM dose did not elicited overt signs of toxicity (i.e. normal body weight gain curve), it was able to induce striatal neurodegeneration (dopamine and Nurr1 reduction, and lipid peroxidation increase). The present study was designed to characterize the cognitive deficits in the current animal model. When during late adulthood PERM treated rats were tested for spatial working memory performances in a T-maze-rewarded alternation task they took longer to choose for the correct arm in comparison to age matched controls. No differences between groups were found in anxiety-like state, locomotor activity, feeding behavior and spatial orientation task. Our findings showing a selective effect of PERM treatment on the T-maze task point to an involvement of frontal cortico-striatal circuitry rather than to a role for the hippocampus. The predominant disturbances concern the dopamine (DA) depletion in the striatum and, the serotonin (5-HT) and noradrenaline (NE) unbalance together with a hypometabolic state in the medial prefrontal cortex area. In the hippocampus, an increase of NE and a decrease of DA were observed in PERM treated rats as compared to controls. The concentration of the most representative marker for pyrethroid exposure (3-phenoxybenzoic acid) measured in the urine of rodents 12 h after the last treatment was 41.50 µ/L and it was completely eliminated after 96 h.