Assessment of ultrasound-assisted extraction combined with supramolecular solvent-based microextraction for highly sensitive cadmium determination in medicinal plant sample by TS-FF-AAS

Abstract

A new analytical method exploiting supramolecular solvent-based microextraction (SUPRAS) combined with ultrasound-assisted extraction to preconcentrate cadmium from medicinal plant, with further determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS), is proposed. The proposed method is based on the cadmium ultrasound-assisted extraction from Ginkgo biloba L. leaf samples with diluted acid (0.10 mol L−1 HNO3), followed by the metal complexation with diethyl dithiophosphate and preconcentration using a supramolecular solvent composed of inverted hexagonal aggregates of dodecanoic acid arranged in tetrahydrofuran/water medium. The limits of detection (LOD) and quantification (LOQ) were found to be 0.11 μg L−1 and 0.36 μg L−1, respectively. Intraday and interday precision assessed in terms of relative standard deviations (RSD, %) were lower than 8.50% to 0.70, 1.75 and 5.00 μg L−1 cadmium solutions. The efficiency of ultrasound-assisted extraction was comparable to microwave-assisted digestion and the method accuracy was checked by analysis of certified reference material (Tomato Leaves, SRM 1573a). Samples of Ginkgo biloba L. were analyzed and cadmium contents between 0.21 and 0.33 μg g−1 were found, thereby showing clearly the importance of investigating toxic metals in medicinal plants. The proposed method is simple, highly sensitive, environmentally friendly and has great potential to be applied in the quality control of medicinal plants aiming trace cadmium determination.