Ligandless, deep eutectic solvent‐based ultrasound‐assisted dispersive liquid‐liquid microextraction with solidification of the aqueous phase for preconcentration of lead, cadmium, cobalt and nickel in water samples

A green and efficient sample preparation method using a deep eutectic solvent‐based ultrasounds‐assisted dispersive liquid–liquid microextraction with solidification of the aqueous phase followed by high performance liquid chromatography analysis was developed for preconcentration and determinati…