Application of magnetic nanoparticles to residue analysis of organochlorine pesticides in water samples by GC/MS

This paper describes a novel magnetic-SPE method for the determination of organochlorine pesticides (OCPs) in environmental water samples by use of Fe3O4-magnetic nanoparticles (MNPs) coated with oleic acid followed by GC/MS. The chemisorption of oleic acid onto Fe3O4-MNPs provides reusability of the developed sorbent materials several times. The effects of different parameters such as pH, desorption solvent, contact time, temperature, ionic strength, and sorbent dosage on the efficiency of magnetic-SPE were investigated. The optimized SPE method involved shaking 50 mL of water sample (pH 4) with 50 mg oleic acid coated Fe3O4(-) MNPs for 1 h, isolating the sorbent with an Nd-Fe-B magnet, and eluting the OCPs with methanol. An ionic strength of 0.1 M and temperature of 15 degrees C provided the maximum extraction efficiency. The LOQs were in the range of 0.006 to 0.048 microg/L. For three fortification levels, recoveries were in the range of 44-108%, with RSD