Synthesis of nanoparticle-decorated biodegradable membranes for use in electro-membrane extraction techniques

The development of more environmentally friendly analytical methodologies is currently a common goal when implementing new procedures. In this regard, microextraction procedures such as electromembrane extraction (EME), based on the use of alternative materials, have been proposed. In particular, EME is one of the most widely used sample preparation techniques, with diverse applications in the analysis of biological, environmental and food samples. It is characterised by facilitating the transport of matter by electrokinetic migration, whereby analytes possessing ionisable functional groups in their structure are extracted directly in their charged form (acidic or basic) through a supported (usually organic) liquid membrane (SLM) into an aqueous phase by the application of an external electric field. With this technique, several groups of analytes (acidic and basic compounds, polar and non-polar, ions or drugs) have been determined in a multitude of formats and extraction devices (such as hollow fibres, flat membranes or microfluidic devices) using different types of supporting materials. Typically, these supports have been plastic materials such as polypropylene, both in the form of hollow fibres and flat membranes. Polyvinylidene difluoride or polyacrylonitrile have also been used, although to a lesser extent. Within the field of green analytical chemistry, the use of alternative materials to classical plastics is a key objective for the synthesis of films or support membranes in EME techniques. In particular, biopolymer derivatives such as chitosan and agarose have recently experienced great importance as biodegradable and sustainable materials, which is a great advantage given the reduction of the environmental impact derived from these processes. The new biopolymeric films synthesised will make it possible to replace the plastic supports traditionally used in EME processes with these new membranes which are biodegradable and sustainable due to their natural source, thus contributing to the trend towards a greener environment. Moreover, the functionalisation of these biofilms with metallic gold nanoparticles will allow the design of customized membranes, thus selecting the analytes to be extracted from complex matrices. Specifically, drugs belonging to different families (non-steroidal anti-inflammatory drugs (NSAIDs) or antibiotics), as well as other substances considered as emerging pollutants (parabens, among others) could be targeted extracted trough their interaction with the biomembrane. Agarose-chitosan based membranes, decorated with metal nanoparticles, have been synthetized and succesfully applied in EME procedures for the selective extraction of NSAIDs, parabens and fluoroquinolones from biological and environmental samples. The presence of nanoparticles in the biomembrane improves the efficiency of the extraction (higher enrichment factors), enabling additionally a targeted and green methodology for the determination of different drugs.