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
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.