Trace determination of cobalt in heather leaf tea by matrix matching calibration assisted flame atomic absorption spectrometry following a dispersive liquid–liquid microextraction utilizing a Schiff base ligand

In this study, an analytical method that involves dispersive liquid–liquid microextraction for extraction and enrichment of Co was developed for its determination in heather leaf tea infusions. N,N’-bis(2-hydroxyacetophenylidene)-1,3-propanediamine was utilized to form the complex extracted in chloroform with methanol as a dispersive solvent. The experimental parameters were optimized to allow for an enhancement of detection power by 35.6-folds compared to direct FAAS measurements while lowering the limit of detection to 0.0154 mg/L and the limit of quantification to 0.0513 mg/L and providing a linear range of 0.050–0.75 mg/L. Spiked recovery experiments were conducted on two brands of heather leaf tea where a matrix matching strategy was employed for further reduction of interferences. The recovery results obtained in the range of 78.7–128.4 % supported the accuracy of the proposed method that promises an economical and easy-to-apply process for the trace determination of cobalt in herbal tea matrices.