Rapid ultrasound-assisted dispersive solid-phase extraction of nonsteroidal anti-inflammatory drugs in urine using oleic acid functionalized magnetic graphene oxide.

We describe an ultrasound-assisted magnetic dispersive solid-phase extraction based on oleic acid functionalized magnetic graphene oxide followed by high-performance liquid chromatography with ultraviolet detection. The method was applied for the simultaneous determination of ibuprofen, diclofenac, naproxen, and mefenamic acid in urine. The application of sonication led to the good dispersion of the sorbent, and consequently, significant shortened the extraction time. The sorbent was successfully characterized by different techniques. The influence of the adsorption parameters was optimized using a rotational central composite design. In order to improve desorption efficiency, parameters such as type and volume of the eluent and sonication time were investigated and optimized through a one variable at a time method. Under the optimum conditions, limits of detection and precision were between 3.0-25 ng/mL (n = 5) and 3.2-7.1%, respectively. The preconcentration factors were found to be 74 for naproxen, 76 for diclofenac, 80 for ibuprofen, and 66 for mefenamic acid corresponding to the absolute recovery within the range of 82.5-100%. Finally, the proposed method was successfully applied for simultaneous determination of target analytes in human urine samples. The relative recovery was within the range of 91.4-113.3%, indicating the good reliability and accuracy of the method.