The New Extraction Techniques Based On Self-assembled Polyelectrolyte Multilayer Films

Compared with other sample pre-treatment technology, solid phase extraction(SPE) and magnetic solid phase extraction(MSPE) become more and more popularfor the preconcentration/separation of trace metal ions because of their characteristicsuch as simple operation, low cost and high enrichment factor. Extraction medium isthe key of the SPE and MSPE, Which affects the sensitivity and selectivity ofextraction method.The so-called layer-by-layer(LBL) is a deposition technique for preparingPEMs through the intermolecular weak interaction. The technique has the advantagesof simple operation, mild experimental condition for preparation, and it couldincorporate many kinds of different compounds into PEMs. And electrostaticinteraction, ionic exchange and chelation(chelating groups incorporated by chemicalmodification) could be the adsorption mechanism for the selective extraction of targetanalytes. Therefore, PEMS as the extraction medium has attracted more and moreattention.The aim of this paper is to combine MSPE or SPE with atomic detector, optimizethe parameters affecting extraction and evaluate the magnetic properfies, adsorptioncapacity and regenerability of the sorbent based on PEMs. The proposed method hasbeen applied to determine the trace elements in real samples. The main researchcontent are lised as follows:(1) A new MSPE sorbent based on PEMs material was prepared and used as theMSPE sorbent, Several factors affecting efficiency such as pH, ultrasonic time,elution conditions were optimized. The magnetic properties, adsorption capacity andreproducibility of the materials were evaluated. MSPE-FAAS was established todeterminate the concentration of trace Cu2+in aqueous solution and was successfullyused for the determination of trace Cu2+in the boiler water, well water and mineralwater. (2) PEMs was prepared by the LBL technique used as the MSPE sorbent fordeterminating the concentration of trace Ag+in the leaching solution of antibacterialproducts and packaging materials. Several factors affecting efficiency were optimized.The selectivity and its analytical performance were evaluated and the proposedmethod has been successfully used for the determination of trace Ag+in the leachingsolution of food plastic wrap, keyboard film and wet paper.(3) A method for the preconcentration/separation of trace Hg2+by using PEMsmodified silica gel as SPE sorbent was established. Several factors affectingefficiency such as the concentration of KI, pH, flow rate, elution conditions wereoptimized. SPE-AFS has been applied in the determination of trace Hg2+in the boilerwater, mineral water and rainwater.