Green surfactant assisted-solidified floating organic drop micro-extraction (SA-SFODME) for the preconcentration of trace cobalt and determination by flame atomic absorption spectrometry (FAAS)

Abstract

This study focuses on refining the solidified floating organic drop microextraction (SFODME) without using chelating agent technique for enhancing the preconcentration of trace cobalt levels. The cobalt ion formed a hydrophobic complex with the help of the anionic surfactant sodium dodecyl benzene sulfonate (SDBS), and this hydrophobic complex was extracted into the 1-dodecanol drop. This serves as a preliminary step for subsequent analysis using flame atomic absorption spectrometry (FAAS). Several factors influencing microextraction efficiency, such as pH, sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate, and temperature, were systematically investigated to determine optimal conditions. Under these optimized parameters, an enhancement factor of 80 was achieved for a 25 mL sample solution. The calibration curve displayed linearity within the 0.01–0.075 mg/L range, with a limit of detection (3s) of 2.8 µg/L and a limit of quantification (10s) of 9.3 µg/L. The relative standard deviation (RSD) for 10 replicate measurements of 10 µg/L cobalt was 2.1%. The method was successfully applied to extract and determine cobalt in reference water samples and various real water samples, showing notably high extraction yields.