Graphitic carbon nitride reinforced nylon 6 nanocomposite-based monolithic thin film for microextraction of carvedilol from biological samples

In this research, graphitic carbon nitride (g-C3N4) was synthesized through thermal condensation method and was used as nanofiller to prepare a novel nanocomposite (NC). In this regard, g-C3N4 was incorporated into nylon 6 (N6) by solvent blending method and afterward, it was solidified as a monolithic thin film through phase separation process. The characterization of N6 and g-C3N4/N6 NC thin films was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The prepared thin film based on g-C3N4/N6 NC was utilized for thin-film microextraction (TFME) of carvedilol (CAR) in deionized water, urine and plasma samples followed by fluorescence spectrometry. The effect of g-C3N4 doping level on the thin film's extraction capability was investigated, indicating the significant effect of g-C3N4 reinforcing in N6 matrices on the extraction efficiency. Central composite design (CCD) was applied to investigate the effect of important factors influencing the extraction and desorption efficiency, and to optimize the extraction and desorption condition. Based on the method validation, limit of detection (LOD) and limit of quantification (LOQ) were 1 and 3.3 ng mL(-1), respectively. The developed method's linearity was in the range of 3.3-100 ng mL(-1), 16.5-500 ng mL(-1), and 16.5-250 ng mL(-1) for deionized water, urine and plasma sample, respectively, with satisfied determination coefficient (r(2) > 0.9912). The repeatability of the method in the terms of intra-day, inter-day and inter-sorbent precisions (n = 8) were 3.6, 7.6 and 8.3%, respectively. Relative recoveries for spiked plasma and urine samples were 86.9% and 82.7%, respectively.