Aida Garcia-Rodríguez

24 Aug 2012

I completed my undergraduate degree in Chemistry at the University of Girona (Catalonia, Spain) in July 2009. In September 2010 I concluded an Interuniversity Master of Applied Chromatographic Techniques.


I started my PhD studies in October 2010 at the University of Girona and in 2011 I got a three years research fellowship from the University. Currently I am working at the Chemistry Department under the guidance of Dr. Clàudia Fontàs and Dr. Víctor Matamoros at the Environmental and Analytical Chemistry unit. My studies are focused on the regeneration of waste water and on the development of analytical methods for the determination of organic contaminants in environmental matrices.


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Abstract


Development of a membrane-based device for the monitoring of antibiotics

Antibiotics are a class of pharmaceutical compounds which are widely used for veterinary and human therapy. Due to their incomplete removal in conventional wastewater treatment plants (WWTPs), considerable amounts of these compounds can be found in different environmental matrices where they can represent a potential ecotoxicologial risk. For this reason, it is of interest the development of reliable analytical methods for routine monitoring of antibiotics in waters, which normally include sample cleanup and preconcentration steps.

Passive sampling is considered a practical technology which is able to achieve the enormous sampling requirements posed by the presence of chemicals in the environment. This technique owns simplicity and cost effectiveness. It is based on free flow analyte molecules from the sampled medium to a receiving phase in a sampling device, as a result of a difference between the chemical potentials of the analyte in the two media. In the case of polar organic pollutants, such as antibiotics, polar organic chemical integrative samplers (POCIS) are often used. However, in this passive sampling design an elution/desorption step of the analytes is needed prior to the final instrument analysis. This drawback can be overcome with the use of permeable membranes devices, where one side of the membrane is exposed to the aqueous environment, while the other is in contact with a strip solution where the analytes are released. Polymer inclusion membranes (PIMs), in which the carrier is incorporated into a gel network of a polymeric material, can be used for this purpose. Hence, the use of PIMs in front of POCIS has several advantages such as an effective carrier immobilization, easy preparation, versatility, and good mechanical properties.

In the present work we have evaluated the use of several PIM compositions for the transport of two families of antibiotics (sulfonamides and tetracyclines) in water samples. Different parameters affecting the membrane system were optimized using as feed phase a mixture of antibiotics at pH 9 and a stripping phase consisting of 1M NaCl. Firstly, the effect of the polymer on the transport efficiency was studied testing two different polymers, cellulose triacetate (CTA) and polyvinyl chloride (PVC). Best results were achieved with the use of CTA. Then, in order to assess the effect of the plasticizer nature and using CTA as a polymer, diverse membranes were created with different plasticizers. Nitrophenyl octyl ether (NPOE) was the plasticizer which allowed better transport efficiencies. Therefore, from our results, it was found that better membrane composition was 46% CTA + 20% Aliquat 336 (carrier) + 34% NPOE. The designed membrane system successfully transported antibiotics contained in environmental matrices such as river and sewage waters after the addition of EDTA to eliminate calcium interaction with tetracyclines. Our present studies are focused on the use of such membranes in special home-made devices to be used as passive samplers for the monitoring of antibiotics in different water matrices.

Acknowledgements

The financial support by Ministerio de Ciencia e Inovación through project CTM2011-28765-C02-02 is gratefully acknowledged. Aida Garcia wants to acknowledge a BR2011/27 research fellowship from the University of Girona.