Magnetic dispersive micro-solid-phase extraction for the preconcentration and extraction of lead (II) and cadmium ions from environmental samples using magnetic CoFe2O4 @ SiO2@4-aminobenzoic acid-functionalized graphene oxide as a green and efficient sorbent

A magnetic dispersive micro-solid-phase extraction as a simple and efficient sample preparation procedure was developed to extract lead (II) and cadmium (II) ions. The microextraction method was enhanced using an ultrasonic bath as a suitable device and a surfactant as a dispersion agent to disperse a sorbent into a low volume of distilled water before injecting it into the sample solution. This procedure increases the sorbent dispersion efficiency and decreases the dispersion time to reduce sorbent degradation. Also, green and selective sorbent (magnetic CoFe2O4 nanoparticles @ SiO2 @ 4-aminobenzoic acid-functionalized graphene oxide) was prepared based on functionalization of graphene oxide with 4-aminobenzoic acid and its magnetization with CoFe2O4 nanoparticles using the solgel technique. Several factors affecting the microextraction process of lead (II) and cadmium (II) ions, including the type of desorption solvent and dispersing solvent, extraction time, desorption time, dispersion time, sample solution volume, sorbent amount, and pH of the solution, were optimized by experimental design and one factor at a time strategy. Under the optimum condition, the calibration curves for the determination of lead (II) and cadmium (II) ions were linear at the concentration ranges of 13.2-235.0 and 16.8-240.0 ng L-1 with a determination coefficient (R-2) of 0.9866 and 0.9839, respectively. Limit of detection and relative standard deviation (n = 3) for the determination of lead (II) and cadmium (II) ions were lower than 5.4 ng L-1 and 4.2%, respectively. The application of the method for analyzing several real water samples indicated that the technique has an excellent relative recovery in the range of 96.2-102.2% with relative standard deviations of less than 4.9%.

Automated summary

A magnetic dispersive micro-solid-phase extraction method was developed for extracting lead (II) and cadmium (II) ions efficiently. The method utilized optimized factors such as desorption and dispersing solvents, extraction and desorption times, sample solution volume, sorbent amount, and pH of the solution to achieve linear calibration curves for the determination of the ions. The method showed low detection limits, good relative standard deviations, and excellent recovery rates when applied to real water samples.