Dispersive liquid-liquid microextraction utilizing menthol-based deep eutectic solvent for simultaneous determination of sulfonamides residues in powdered milk-based infant formulas

An eco-friendly, fast, sensitive dispersive liquid–liquid microextraction (DLLME) method followed by UPLC-MS/MS was developed and validated for multi-residue determination of sulfonamides in milk-based infant and young children formulas. In this study, a natural deep eutectic solvent was synthesized using menthol and octanoic acid at a molar ratio of 1:2 for the extraction of seven sulfonamides in infant formulas. Different extraction parameters including volume of deep eutectic solvent, vortex time, centrifugation time, sample volume and pH were investigated and optimized. Under the optimum conditions, determination coefficients of ≥ 0.9993 were obtained for all studied analytes. The limits of detection ranged from 0.5 to 1.5 µg Kg⁻¹. The extraction recoveries were in the range of 82.6–100.1% with RSDs %≤ 7.5. To investigate the applicability of the proposed method, it was applied to determination of the studied sulfonamides in thirty milk-based infant formulas of different brands. The environmental impact of the presented method was evaluated using three assessment tools namely: Eco-Scale Assessment (ESA), Green Analytical Procedure Index (GAPI) and Analytical GREEnness metric (AGREE). The characteristic performance of the developed DLLME-UPLC-MS/MS method was also compared with other reported methods.