Magnetic solid phase extraction of phthalate products from bottled, injectable and tap waters using graphene oxide: Effect of oxidation method of graphene

Phthalate esters (PAEs) are considered as an endocrine disrupting chemicals which cause harm on human and environment. Therefore, PAEs concentration should be determined and evaluated. In the present work, graphene (G) was oxidized with either nitric acid, ammonium persulfate or hummer method, to produce the corresponding graphene oxides (GO): GO-NA, GO-APS and GO-HUM, respectively. Magnetite was deposited on graphene and oxidized graphene to produce the magnetic sorbents: MG, MGO-NA, MGO-APS and MGO-HUM. These were used for optimization of simultaneous magnetic solid -phase extraction (MPSE) method of five phthalate products (DMP, DEP, BBP, DIBP, and DBP) from bottled, injectable and tap water. The highest recoveries were achieved using 40 mg of MGO-APS at pH5, sample volume 50 ml, elution with 5 ml ethyl acetate, shaking time 45 min, and elution time 15 min. The following figures of merits were achieved: detection limits range (0.004-0.013 mg.L-1), %RSD range(0.62-6.02)%, %bias range ((-16.6)-(-7.0))%, and sensitivity range (79-149)L-1.mg. Application of the optimum MSPE on bottled, injectable, and tap water showed that DEP, BBP, DIBP, and DBP were present in bottled and injectable water. The adsorption of PAEs on graphene oxide was best fitted with Langmuir model.