Curcumin loaded magnetic graphene oxide solid-phase extraction for the determination of parabens in toothpaste and mouthwash coupled with high performance liquid chromatography

A simple and rapid sample pretreatment namely dispersive magnetic solid phase extraction (DMSPE) was performed for simultaneously extraction of four parabens from toothpaste and mouthwash samples. Curcumin loaded magnetic graphene oxide, an environmentally friendly sorbent, was synthesized and characterized by FTIR, VSM, SEM, TEM and EDS and successfully confirmed. Liquid chromatography with photodiode array detection (HPLC-DAD) was used for analysis of paraben species. Parameters affecting the extraction efficiency were studied and optimized through tunvariate analysis and experimental design. Under optimum conditions, method showed good linearity (0.001-5 mu g mL(-1)) in the selected range with coefficient of determination (R-2) from 0.9938 to 0.9993. Limits of detection (LOD) ranged from 0.0004 to 0.001 mu g mL(-1) and enrichment factors from 36 to 55. The precision of the method is expressed as relative standard deviation. The repeatability of the extraction procedure was checked over one day and then, the reproducibility of the method between three days at three levels of concentration. The results of this consideration were satisfactory. The optimized method was applied to determination of parabens in toothpaste and mouthwash. The relative recoveries in these real samples were in the range of 71.62-120.34%.