Ultrasound assisted dispersive solid-phase extraction coupled with high-performance liquid chromatography-diode array detector for determination of caffeine and carbamazepine in environmental samples using exfoliated graphite/chitosan hydrogel

In this study, an exfoliated graphite/chitosan hydrogel was used as an adsorbent in ultrasound assisted dispersive solid-phase extraction of caffeine (CAF) and carbamazepine (CBZ) from water samples. The analytes were quantified using high performance liquid chromatography-diode array detector. The adsorbent material was characterized using X-ray diffraction, Fourier transform-infrared spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The most influential experimental factors were optimized using a central composite design. Under optimum conditions, the limits of detection (LOD) and quantification (LOQ) for CAF were 0.018 µg/L and 0.06 µg/L, respectively. While for CBZ, the LOD and LOQ were 0.011 µg/L and 0.04 µg/L, respectively. Percentage recovery ranged from 87 to 112%, and relative standard deviation (%) was less than 6%. This method was applied for the determination of CAF and CBZ in wastewater and river water samples.