Simple and Green Heat-Induced Deep Eutectic Solvent Microextraction for Determination of Lead and Cadmium in Vegetable Samples by Flame Atomic Absorption Spectrometry: a Multivariate Study

In this study, a simple, green, and cheap analytical procedure based on heat-induced deep eutectic solvent microextraction (HI-DES-ME) coupled with flame atomic absorption spectrometer (FAAS) was developed for the determination of Pb(II) and Cd(II) in vegetables. After the preliminary experiment, response surface methodology (RMS) based on central composite design (CCD) was used for the optimization of critical factors such as pH of sample solution, amount of extraction solvent, temperature, and amount of ligand. Microwave step was applied for the digestion of vegetable samples. Under optimum conditions obtained by the CCD, calibration graphs for Pb(II) and Cd(II) were linear in the concentration range of 0.5–250 and 1.0–300 ng mL−1, respectively. Limits of detection (LODs) and sensitivity enhancement factor (SIFs) were found in the range of 0.17–0.35 ng mL−1 and 93–67 ng mL−1, respectively. Relative standard deviations (N = 10, RSDs%) for Pb(II) (10 ng mL−1) and Cd(II) (50 ng mL−1) were 3.7% and 2.3%, respectively. In order to validate the proposed method, certified reference material (CRM) and spiked samples were used. Experimental results showed that there was no significant difference between the obtained and certified values. Then, the proposed method was successfully applied for the preconcentration and determination of Pb(II) and Cd(II) in different vegetables.