magnetic solid-phase extraction in combination with hollow fiber liquid phase microextraction for preconcentration and determination of trace amounts of chlorpyrifos pesticide in aqueous samples

A novel sample pre-treatment approach based on the integration of magnetic solid-phase extraction (mspe) and hollow fiber liquid phase microextraction (hf-lpme) prior to gas chromatography-mass spectroscopy (gc-ms) was developed for preconcentration and determination of trace amount of chlorpyrifos pesticide in aqueous samples. in this study, nanocomposites of azolla modified with magnetite nanoparticles were prepared as a cheap natural adsorbent [1] for adsorption of chlorpyrifos as an organophosphate insecticide. the size and structure of magnetite modified azolla nanocomposite (manc) was studied by xrd, ft-ir, edx, bet, fesem, tem and vsm. the manc was used in magnetic solid phase extraction (mspe) as adsorbent for sorption of chlorpyrifos parameters prior to hollow fiber liquid phase microextraction (hf-lpme) [2]. all of affecting parameters during adsorption/desorption of chlorpryfos in mspe procedure, such as sample volume, contact time, ph, and ionic strength, were studied and optimized (oa16) by taguchi experimental design method. after extraction by mspe method under the optimum conditions of adsorption (sample volume= 50 ml, contact time = 30 min, ph= 3, sorbent weight= 0.05 gr, ionic strength= 0.01) and desorption (solvent= ethanol, solvent volume= 2 ml, contact time=10 min), 2 ml of the ethanolic solution containing the desorbed chlorpyrifos was dispersed in 16 ml aqueous solutions of 10% nacl in an extraction vial and the solution was extracted by hf-lpme process. after optimizing the experimental parameters by taguchi experimental design method (oa9), the optimum parameters were obtained to have higher extraction efficiency (sample volume= 18 ml, contact time= 15 min, salt amount= 10% w/v, extraction solvent=1-octanol, extraction solvent volume= 30 µl). the final extract solution was analyzed by gc-ms. thus the present mspe-hf-lpme method is a good way to preconcentrate and determines trace amounts of chlorpyrifos from the channel, well, and river water samples.