Evaluation of natural alternatives binders for in situ determination of interest environmental contaminants by using diffusive gradients in thin films technique (DGT)

• Grant number: 13/07777-0
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2013
• End date: July 31, 2015
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Paulo Sergio Tonello
• Grantee: Paulo Sergio Tonello
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental de Sorocaba. Sorocaba , SP, Brazil
• Associated researchers: André Henrique Rosa

Abstract

The contamination of water bodies by discharge of industrial and domestic effluents is a major problem that threatens human health and the equilibrium of aquatic ecosystems. Techniques that use passive samplers which allow sampling "in situ", for example, "Diffusive gradients in thin films" (DGT) are important tools for monitoring this contamination. The DGT technique is based on the 1st Fick's law for diffusion. Routine determination of metals is employed as the binder, discs acrylamide / agarose impregnated with the resin Chelex-100. The scope of the technique, however, is limited by environmental conditions and the characteristics of the interactions between the resin and the contaminants. Their results represent labile fractions of contaminants in relation to that resin, but do not guarantee also that represent the bioavailable fraction of the contaminants. The use of natural materials as binders for DGT technique make it possible to obtain results closer to those existing in natural aquatic environments, where the lability is comparable to the bioavailability. In this project for the determination of metallic species labile of environmental interest that can be potentially toxic for example Al, Cd, Co, Cr, Cu, Mn, Pb, Ni, Zn, will be evaluated as binders for DGT technique, thin films produced with the biopolymer chitosan, peat and the humin fraction extracted from the peat. Will be prepared thin films of chitosan (natural or reticulated) and peat or humin immobilized in low melting agarose. Their capabilities for retention of analytes and kinetics of adsorption will be evaluated. The analytes who present the best interactions with binders proposed, will be tested in the DGT technique for evaluation of its efficiencies as potential binders before the main variables of the systems as the immersion time, pH and ionic strength. Also will be investigated the effects of potential interferences. Using the new binders, DGT will be tested with natural water samples in the laboratory and "in situ", using commercial discs of acrylamide / agarose as diffusive material. The results will be compared with those obtained using DGT samplers commercial or other technical consecrated as solid phase extraction. As a result of the project, expected to gather information to expand the use of DGT technique for new analytes and / or provide results closer to bioavailable values found in natural aquatic environments. (AU)