Determination of cholecalciferol (vitamin D3) in bovine milk by dispersive micro-solid phase extraction based on the magnetic three-dimensional graphene-sporopollenin sorbent

In this research, a new magnetic sorbent material composed of three-dimensional graphene aerogel decorated with Fe3O4 nanoparticles attached to hollow sporopollenin exine capsules was synthesized and applied for extraction of vitamin D-3 before HPLC-UV analysis. The adsorbent was characterized by FT-IR, SEM, VSM, and zeta potential techniques. The important parameters of the extraction process, including adsorbent dosage, desorption conditions, adsorption time, pH, and salt concentration, were investigated. Under the optimized condition, the method analytical figures of merit were evaluated as follows: linear dynamic range, 10-500 mu g L-1; limit of detection, 3.01 mu g L-1; determination coefficient (R-2), 0.9960; intra-day RSD, 5.28%; and inter-day RSD, 8.17%. The applicability of the method was assessed for the determination of vitamin D3 in different unfortified and fortified bovine milk samples, and the recoveries in the 71.8-113.3% range with the RSDs within 1.4-7.0% were obtained.