A novel magnetic-assisted ionic liquid-based microextraction method (MA-ILBME): Specific design system for sensitive spectrophotometric analysis of paracetamol as a pharmaceutical pollutant in environmental samples

Monitoring paracetamol levels in environmental samples is essential, as this widely used pharmaceutical can degrade water quality and adversely affect both ecosystems and human health. To address this issue, a novel, simple, sensitive, and accurate method has been developed. This method employs a functionalized ionic liquid, 2-(4-hydroxybenzyl)hydrazinium chloride ([HBH][Cl]), specifically designed to structurally mimic paracetamol and function as a complexing agent. Following strong interactions between the ionic liquid and paracetamol in aquatic samples, the ionic liquid is magnetized and then separated using a magnetic field. The synthesis of the magnetic ionic liquid was confirmed using a variety of analytical techniques, including Fourier-transform infrared spectroscopy, carbon and proton nuclear magnetic resonance (¹³CNMR and ¹HNMR), vibrating sample magnetometry, and elemental analysis. The interaction between the ionic liquid and paracetamol was characterized through density functional theory calculations, UV-Vis spectroscopy, and CHNO analysis, which confirmed the formation of strong hydrogen bonds and the resultant complexation. Critical parameters influencing the measurement of paracetamol in aquatic samples were systematically optimized. The method's performance, assessed through key figures of merit, demonstrated excellent analytical capabilities: a limit of detection of 0.087 μg L^-1 at a 99.7 % confidence level, a limit of quantification of 0.15 μg L^-1, a linear dynamic range of 1.0-200.0 μg L^-1, intra-day relative standard deviation of 1.12 %, inter-day RSD of 3.04 %, preconcentration factor of 119, and concentration factor of 95. Furthermore, the method achieved a recovery efficiency of 99-102 % in real samples and successfully quantified paracetamol in a commercial paracetamol tablet.