Determination of four bisphenols in water and urine samples by magnetic dispersive solid-phase extraction using a modified zeolite/iron oxide composite prior to liquid chromatography diode array detection

A novel approach is presented to determine four bisphenols in water and urine samples, employing magnetic dispersive solid-phase extraction combined with liquid chromatography and diode array detection. A modified zeolite-based magnetic composite was used as an efficient sorbent, combining the advantages of magnetic materials with the remarkable properties of zeolites. A multivariate optimization design was employed to optimize some experimental factors affecting magnetic dispersive solid-phase extraction. The method was evaluated under optimized conditions (i.e., amount of sorbent, 50 mg; sample pH, unadjusted; NaCl concentration, 1.25%; extraction and elution time, 2 min; eluent solvent, ethanol; eluent solvent volume, 400 mu L), obtaining good linearity with correlation coefficients ranging between 0.995 and 0.999 (N = 5) (from 2 to 250 mu g/L for bisphenol A, bisphenol AP, and bisphenol P and from 5 to 250 mu g/L for bisphenol AF). Method repeatability was assessed obtaining coefficients of variation between 3 and 11% (n = 6). Finally, the method was applied to spiked real samples, obtaining for water samples relative recoveries between 83 and 105%, and for urine samples between 81 and 108% for bisphenol A, bisphenol AP, and bisphenol AF, and between 47 and 59% for bisphenol P.