Vortex-assisted dispersive liquid-liquid microextraction using a novel ferrofluid based on magnetic toner particles and a natural eutectic mixture for elemental determination in water samples

Heavy metals in water are persistent and toxic contaminants, making their monitoring crucial due to the implications for environmental and public health. Accurately determining their presence requires sensitive analytical techniques, supported by effective sample pretreatment to ensure proper enrichment and reduce matrix effects. While liquid-liquid microextraction methods help minimize reagent usage and waste, they often depend on hazardous extractants or involve complex separation processes. Therefore, there is a clear need for uncomplicated and sustainable microextraction procedures that combine efficient preconcentration with simplified phase separation to determine these analytes in water samples. In this research work, a ferrofluid-based vortex-assisted dispersive liquid–liquid microextraction (VA-DLLME) was optimized using a multivariate approach. Under the globally optimized conditions (i.e., extraction mixture weight, 8.1 g; amount of HCl, 130 mg; pH extraction mixture, 4.8; ferrofluid weight, 100 mg; NEM/toner ratio, 100:1; extraction time, 1 min; 8-hydroxyquinoline concentration, 1%; elution time, 1 min; and HCl concentration, 3 M), the method exhibited excellent analytical performance. Specifically, it demonstrated high linearity for all target analytes (R 2 > 0.997), limits of detection ranging from 0.12 to 3 μg L −1 and limits of quantification spanning 0.4 to 10 μg L −1 . Repeatability, evaluated at two levels (200 and 400 μg L −1 ), ranged from 3 to 9%. Furthermore, recoveries in untreated, reclaimed, and non-potable domestic water samples ranged from 91 to 109%. Moreover, the developed ferrofluid-based VA-DLLME procedure represents a straightforward, rapid, and energy-efficient methodology for the determination of heavy metals in water. By utilizing commercially available toner particles, the synthesis of magnetic agents is avoided, while the NEM provides a non-hazardous extractant alternative. Notably, the ferrofluid removes the need for centrifugation, streamlining the workflow. This approach not only enables effective multielemental determination but also lays the groundwork for sustainable practices, including the potential use of recycled toner.