Medicine Dropper-Assisted Solvent Bar Micro-Extraction (SBME) of Imidacloprid Pesticide From Fruit Samples Utilizing a Facemask's Meltdown Layer as a Holder of a Deep Eutectic Extraction Solvent

In response to an emerging need for the development of advanced analytical methods to guarantee food quality and safety, this study presents a novel medicine dropper-assisted SBME (MD-SBME) that was developed. The technique uses a meltdown layer of a facemask (MLF) as a holder of the extraction solvent. A hydrophobic natural deep eutectic solvent (NADES) made from thymol and menthol was used as the extraction solvent during the MD-SBME analysis of imidacloprid pesticide in fruit samples. Characterization of the NADES was done using Fourier-transform infrared spectroscopy (FT-IR), and the experimental results confirmed that it was successfully synthesized. The MD-SBME parameters, like ionic strength, sample pH, elution solvent type, elution solvent volume, type of DES and extraction solvent volume, were studied and optimized using both the univariate and multivariate approaches. The greenness of the MD-SBME technique was evaluated using the Complementary Modified Green Analytical Procedure Index (ComplexMoGapi) algorithm, and the total score was 85. A total score of 65 was obtained when the practicality of the MD-SBME procedure was evaluated using the blue applicability grade index (BAGI) metric tool. HPLC-PDA was used for the analysis of imidacloprid residues in fruit samples using the developed MD-SBME technique. Under the optimum conditions, limits of detection and quantification were in the range of 0.007–0.02 and 0.02–0.069 $\mu g$ g⁻¹, respectively. The correlation of determinations (R²) for pineapple, pear and apple samples were 0.9986, 0.9982 and 0.9973, respectively. The extraction recoveries of these fruit samples ranged from 72% to 110%. Good precision was obtained when the MD-SBME technique was used to analyse imidacloprid residues in real sample, as all the percentage relative standard deviation (%RSD) were below 5%.