A simple microwave-assisted synthesis of cobalt ferrite nanoparticles and its application for the determination of lead ions in rooibos (Aspalathus linearis) tea

•CoFe2O4 nanoparticles were used to preconcentrate Pb ions from rooibos tea samples.•Detection sensitivity of the FAAS system was enhanced by about 80 folds.•LOD and LOQ values of lead were calculated as 5.3 and 17.6 µg/L, respectively.•Recovery results were calculated in the range of 77–125% using matrix matching method. In this study, a magnetic sorbent assisted dispersive solid phase extraction (DSPE) method was used to preconcentrate lead ions from rooibos tea samples for determination by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). Cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs) were synthesized by microwave assisted digestion. Limits of detection and quantification were calculated as 5.3 and 17.6 µg/L, respectively, in a linear dynamic range of 20–800 µg/L. The enhancement factor of the developed method was found to be 80-folds when compared to the detection limit of the regular FAAS system. The percent recoveries obtained for rooibos tea samples spiked at different concentrations were in the range of 77 – 125%, with high repeatability as indicated by low standard deviations. The findings of the study demonstrated that the CoFe2O4 MNPs-based extraction method is a straightforward, fast, affordable, safe, and eco-friendly approach to qualifying/quantifying lead with high precision in the selected beverage sample.