Magnetic field-assisted solid-phase extraction of nucleoside drugs using Fe3O4@PANI core/shell nanocomposite

A new magnetic field-assisted solid-phase extraction (MFA-SPE) procedure was developed by merging the features of magnetic solid-phase extraction and magnetic in-tube solid-phase microextraction. The MFA-SPE method was coupled with HPLC-UV and applied for the separation and determination of anti-HIV drugs in biological fluids. Magnetic Fe3O4@PANI nanocomposite with core/shell structure was synthesized and used as the extraction phase. It was characterized by FT-IR, SEM, and EDX techniques. Type and volume of eluting solvent, magnetic field intensity, and pH, ionic strength, and volume of the sample solution were studied as the influential parameters. The calibration graphs were linear in the range of 1-5000 ng/mL, with linear regression coefficients greater than 0.99. The LOD was calculated 0.1 ng/mL for both analytes. For six replicated analyses of sample solutions containing 500 ng/mL of zidovudine and lamivudine, the intra-day and inter-day RSDs were calculated 4.1-8.8% and 3.2-13.7%, respectively. Under the optimized conditions, the mean recoveries (n = 3) of the analytes in spiked urine samples were obtained 85.1-103.7%. The maximum cartridge adsorption capacity of the Fe3O4/PANI sorbent was obtained 3.9 +/- 0.34 and 1.9 +/- 0.25 mu g/g for zidovudine and lamivudine, respectively. The method applicability in complex matrices was evaluated by the determination of zidovudine and lamivudine in urine samples and commercial pharmaceuticals. Exposing the magnetic sorbent to the external magnetic field led to remarkable higher extraction efficiencies for the selected drugs.