Integrating monolithic sorbent micro-solid-phase extraction with anodized screen-printed graphene electrode for...

A novel analytical method is proposed that integrates monolithic sorbent micro-solid-phase extraction (µ-SPE) with an anodized screen-printed graphene electrode for the determination of serotonin (SER). Monolithic sorbent µ-SPE offers a straightforward and efficient pretreatment method for removing of interfering substances, thereby enhancing the selectivity of SER analysis before being coupled with an electrochemical sensor. Under optimal conditions, the integration of monolithic sorbent µ-SPE with the electrochemical sensor provided a broad linear range of 50-1500 nM for SER detection, with detection and quantification limits of 4.78 and 15.94 nM, respectively. The developed sensor exhibited excellent reproducibility (RSD < 10%) and good stability over a period of 6 months. Furthermore, the proposed method can detect SER even in the presence of ascorbic acid and uric acid at their normal levels in human biological fluids. This method was successfully applied to determine SER levels in real urine samples with an acceptable recovery range of 93.76%-124.14%. The analytical results derived from the developed methodology are strongly correlated with those obtained using the standard high-performance liquid chromatography method.