represent data in the experimental domain at points which are notincluded in the regression, showed to be non-significant (p = 0.54)relative to the pure error, indicating a good response to the model.On the basis of results of the BBD, two 2D contour plots are illus-trated in Fig. 6, which portray the interaction effects between thevolume of elution solvent (n-hexane) and the elution time (Fig. 6a)and between the sorbent amount and the elution solvent volume(Fig. 6b). When low amounts of n-hexane are introduced (Fig. 6a),the extraction efficiency declines irrespectively of the contact timebetween n-hexane and Fe3O4@SiO2@C18 (elution time). Higheryields were obtained when higher amounts of sorbent were usedfor the extraction. The reflected interaction effects between sor-bent amount and n-hexane volume (Fig. 6b), demonstrated that thehighest recovery of the target analytes was observed at the highestvalues of both variables.Finally, optimal extraction conditions were obtained using thedesirability function of the statistical software. The optimal con-ditions to extract EDCs from milk samples with the aid of MSPEwere: 17 mg of Fe3O4@SiO2@C18 as sorbent and 2.3 mL n-hexaneas elution solvent, for an elution time of 4 min. Under optimal condi-tions, the model predicted maximum total extraction profitabilityof 97%. In order to verify the accuracy of the model, three addi-tional experiments were conducted, under optimal conditions. Theexperimental average recovery obtained was 93%, which was ingood agreement with the predictive value, indicating the adequacyof the response model for the extraction process.