Micro Solid Phase Extraction of Some NSAIDs from Environmental and Biological Samples Using Porphyrin-Functionalized Graphene Sheets as an Efficient Sorbent Followed by HPLC-UV

Non-steroidal anti-inflammatory drugs are used in the treatment of rheumatoid arthritis, inflammation, infectious and other painful musculoskeletal disorders [1]. Despite these therapeutic advantages, long-term and excessive exposure causes adverse side effects including kidney problems, intestinal ulceration, renal failure and even coma and death [2]. In addition, they can enter to the urban water system and threat the environment and ecosystem [3]. So, to monitor the trace concentration of these drugs in biological and environmental matrices, developing of sensitive, reliable, convenient, fast, eco-friendly and economical sample preparation methods is essentially needed. With this purpose, in this work, a porphyrin-functionalized graphene nanosheet was synthesized and employed as an efficient sorbent. The synthesized sorbent was utilized for micro solid phase extraction of some non-steroidal anti-inflammatory drugs (ketorolac, meloxicam, diclofenac and mefenamic acid) followed by high performance liquid chromatography. Optimization of the experimental factors of adsorption and desorption including sorbent amount, sample pH, sample and eluent flowrates, eluent volume and number of desorption cycles was performed with the aid of the response surface methodology with central composite design. Under the optimal conditions, the calibration curves were linear within the range of 2.0-600 ng mL-1 and limits of detection were found between 0.5-2.0 ng mL-1. Intra- and inter-day RSD% (n = 3) of the spiked urine samples at three level concentrations of 25, 100 and 300 ng mL-1 were less than 10%. The relative recoveries of the real samples were calculated in the range of 85.2 to 98.6%. Eventually, the method exhibits proper sensitivity, good repeatability, high reusability and acceptable precision and accuracy.