Title : Electrospun nanofibers sorbents for pre-concentration of pp -1,1-dichloro-2,2 bis-(4-chlorophenyl) ethylene (pesticide) with subsequent desorption by pressurised hot water extraction

Abstract:

One great challenge for analytical chemists is the development of pre-concentration technique that can capture environmental toxicants at the level that new legislations expect. Until recently, solid phase extraction methods were the method of choice. In the recent time, chemically tuned nanofibres are making serious inroad. In this study, SPEs with electrospun polystyrene (PS) nanofibers (130-500 nm) incorporating a potassium salt of imidazole-1-carbodithioate were evaluated as potential sorbents for the pre-concentration of a model Organochlorine pesticide; pp-1,1-dichloro-2,2 bis-(4-chlorophenyl) ethylene (DDE). The efficiencies of adsorption and desorption by pressurized hot water extraction (PHWE) of DDE stock (0.25-2.0 µg L-1) on the nanofibres were investigated and monitored with GC-ECD. Parameters such as time, temperature and pressure of extraction, sample volume, DDE concentration and sorbent mass were optimized. The maximum sorption of DDE (0.50 µg L-1) on electrospun PS and carbodithioate incorporated PS nanofibers was at 43.7% and 94.6% respectively in 20 min, while optimal desorption on the PHWE system was 96.5 % in 30 min. Incorporation of carbodithiote doubled the sorption efficiency of PS and achieved a LOD of 0.234 ng L-1 for DDE. It would seem that the use of electrospun nanofibers as sorbent material with subsequent desorption by PHWE has great potential and provides an opportunity to eliminate organic solvents especially for procedures aimed at monitoring organic pollutants in the environment.

Biography:

Dr. David Adeyemi studied Biochemistry at Obafemi Awolowo University, Ile-Ife Nigeria, where he obtained B.Sc. in 1994 and outstanding second class upper. He holds M.Sc. in Pharmaceutical chemistry in University of Lagos in 2001.  He joined the Research group of Prof. Nelson Torto at Rhodes University, Grahamstown in 2009 to complete his research work.  He completed his Ph.D. in Pharmaceutical Chemistry of the University of Lagos. He currently lecture in University of Lagos and acquired vast research experience in the field of analytical and separation science, his recent advanced research trend was the application of functionalized electrospun nanofibres for pre-concentration of trace analyte of organic and heavy metals contaminants. He has a sound knowledge of instrumentation including chromatograph (GC, HPLC), spectroscopy (FTIR, UV, NMR) and scanning electron microscopy. He has attended international and local conferences and had publications in international Journals of high impact value.