An air-assisted dispersive liquid phase microextraction method based on a hydrophobic magnetic deep eutectic solvent for the extraction and preconcentration of melamine from milk and milk-based products.

Abstract

In the current research, a fast and sustainable air-assisted hydrophobic magnetic deep eutectic solvent-based dispersive liquid phase microextraction followed by UV-Vis spectrophotometry measurements was optimized for the extraction and determination of melamine in milk and milk-based products. The central composite design was applied for the optimization of factors affecting the recovery of melamine. Quantitative extraction of melamine was achieved using hydrophobic magnetic deep eutectic solvents prepared from a mixture of octanoic acid, aliquat-336, and cobalt(II) chloride. The optimum conditions for extraction were found as follows: 6 extraction cycles, pH 8.2, extraction solvent volume 260µL, and acetone volume 125µL.Interestingly, a centrifugation step was not required to achieve phase separation. Under the optimum conditions, melamine was determined in the linear range of 3-600ngmL-1, the limit of detection (3Sblank/m) of 0.9ngmL-1, and the enrichment factor of 144. The validation of the method was investigated by the analysis of reference materials. Consequently, the method was successfully applied for the analysis of melamine residues in milk and milk-based products.