Cu (II)-based metal-organic framework functionalized with graphene oxide as a sorbent for the dispersive micro-solid-phase extraction of losartan potassium from water

In this study, a new metal–organic framework (MOF) based on copper (II) functionalized with graphene oxide (MOF-Cu@GO) was successfully synthesized and applied as an efficient sorbent for dispersive micro-solid phase extraction (D-μSPE) of losartan potassium (LP) from water. The MOF-Cu@GO sorbent was characterized using DRX, FTIR, XPS, TGA, RAMAN, BET, SEM, EDX, and potential Z. The influence of different parameters in the D-μSPE method was studied and optimized using the fractional factorial design 2^5–1 and central composite design. The results indicated that the adsorption process was spontaneous and endothermic followed the pseudo-second order model kinetics and the Freundlich isotherm. The maximum adsorption capacity of MOF-Cu@GO sorbent was 415 mg g⁻¹. The adsorption mechanism proposed of LP onto MOF-Cu@GO proceeded via electrostatic interaction, hydrogen bonds, unsaturated sites of the ligand, and π-π interactions. The microextraction procedure was followed by determination of LP with high performance liquid chromatography (HPLC–UV-Vis). Under optimized conditions, the limits of detection and quantitation were found to be 25 and 80 ng ml⁻¹ respectively, the method exhibited a linear response (r = 0.998) in the concentration range of 0.1–50 µg ml⁻¹ of LP, with a relative standard deviation less than 2% (n = 5). The D-μSPE method showed preconcentration factor of 684.9 and high percentage of LP extraction of 99.78% ± 2.62, the accuracy of the method was demonstrated by studying the recovery of LP from water samples of 100.3 ± 1.06. The material obtained can be used up to 3 cycles with time for the sorption and determination of 30 min indicating good stability and reusability. The MOF-Cu@GO proposed is an efficient and fast sorbent in the D-μSPE for determination of LP from aqueous solutions.