Magnetic CNTs/MnO2/chitin nanocomposite for preconcentration and detection of trace narcotics in biological samples using D-μ-SPE method

This study reports successful synthesis and application of a multifunctional magnetic nanocomposite, comprising MWCNTs, MnO₂, and mealworm skin-extracted chitin, as a splendid sorbent for preconcentration and determination of narcotic drugs papaverine, noscapine, codeine, and morphine in complex biological matrices, using d-μ-SPE (dispersive micro-solid-phase extraction). Characterization via FT-IR, FE-SEM, XRD, EDS, TGA, VSM, and BET analyses confirmed the nanocomposite's structural integrity, high surface area (107.68 m²/g), mesoporosity, and superparamagnetic behaviour, which altogether enhance adsorption capacity and facilitate facile and rapid magnetic separation. Adsorption studies demonstrated adherence to Langmuir and pseudo-second-order models, indicative of monolayer adsorption on homogeneous active sites. Statistical optimization using Central Composite Design allowed precise modulation of parameters influencing adsorption and desorption phases, improving extraction recoveries and method reproducibility. Optimal conditions for maximum analyte recovery within short extraction and desorption times included a sample pH around neutrality (7.3), adsorbent dosage of 5.8 mg, and the usage of a 50:50 ethanol-acetonitrile solvent mixture for desorption. With LODs as low as 0.10 ng/mL, broad linear dynamic ranges, and relative standard deviations under 4.8%, the method exhibited remarkable analytical performance. Application to real samples, including plasma, breast milk, urine, and saliva, yielded recoveries between 93.36% and 102.85%, which vouchsafed robustness and minimal matrix interference. Overall, exploiting a novel magnetic nanocomposite, the new environmentally-compatible, rapid, and sensitive UA-D-μ-SPE method offers a powerful tool for trace-level detection of narcotic drugs, leading to enhanced capabilities in forensic and clinical toxicology.