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

Abstract

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.