A regenerable sorbent composed of a zeolite imidazolate framework (ZIF-8), Fe3O4 and graphene oxide for enrichment of atorvastatin and simvastatin prior to their determination by HPLC.

Graphene oxide (GO), nanosized Fe3O4 and zeolite imidazolate framework-8 (ZIF-8) were hybridized as a multifunctional sorbent for use in microextraction. The sorbent was characterized by SEM, TEM, XRD and FTIR. The composite is porous, has a high specific surface (> 600 m2·g-1) and is paramagnetic. The GO sheets are shown to act as carriers for the Fe3O4 nanoparticles and ZIF-8. The composite is a viable material for the preconcentration of atorvastatin and simvastatin from urine prior to their determination by HPLC with PDA detection. The limits of detection are 116 and 387 pg·mL-1, respectively. Recoveries from spiked urine samples range between 84.7 and 95.7%, with relative standard deviation of ≤4.5%. Enrichment factors range from 169 to 191. The method was successfully applied to the determination of atorvastatin in urine. Moreover, this sorbent is regenerable and recyclable for at least seven times without obvious decrease in performance. Graphical abstract A composite sorbent composed of a zeolite imidazolate framework, Fe3O4 and graphene oxide was applied to the extraction of statins in urine prior their determination by HPLC.