Micelle-Mediated Extraction and Flame Atomic Absorption Spectrometric Method for Determination of Trace Cobalt Ions in Beverage Samples

Abstract

A new method has been developed for preconcentration of cobalt at trace levels in beverage samples using calcon carboxylic acid as chelating agent and cetyl pyridinium chloride as an auxiliary ligand and entrapped into Triton X-114 prior to its determination by flame atomic absorption spectrometry (FAAS). The main parameters affecting cloud point extraction (CPE) efficiency such as pH, concentration of the complexing agent, cationic and nonionic surfactant concentration, salt effect, the equilibrium time, and temperature were investigated and optimized. After optimization of the CPE conditions, a preconcentration factor of 60, an enhancement factor of 106, and a detection limit of 0.20 μg L−1 by (R2 = 0.9978) were obtained from a calibration curve constructed in the range of 0.7–100 μg L−1. The proposed preconcentration procedure was successfully applied to the determination of cobalt ions in some real samples including natural drinking water, tap water, and beer and wine samples. The accuracy and validity of the proposed CPE/FAAS method was tested by means of five repeated analysis of reference standard materials (TM-253, a low level fortified water standard for trace elements). A good agreement between analytical results (28.8 and 28.5 μg L−1 with calibration curve and standard addition curve method, respectively) and certified value (27.9 μg L−1) for Co (p < 0.05) were obtained and verified by means of calibration curve and standard addition curve method using CPE procedure.