Preparation of new hydrophobic deep eutectic solvents and their application in dispersive liquid-liquid microextraction of safranine T and ponceau 4R in water samples

A vortex-assisted liquid-liquid microextraction method combined with high performance liquid chromatography-diode array detector was developed for the determination of ponceau 4R and safranine T pigments in water samples. A new generation of hydrophobic deep eutectic solvents formed from octanoic acid（as hydrogen bond donor）and benzyltriethylammonium bromide，benzyltributylammonium bromide，benzyltriethylammonium chloride and benzyltributylammonium chloride（as hydrogen bond acceptor）in different molar ratios were prepared and used as extraction solvents. The optimum extraction conditions were as follows： extraction solvent prepared by benzyltributylammonium chloride and octanoic acid （1∶2，molar ratio），extraction solvent volume of 75 μµL， extraction time of 1 min，solution pH of 7 and salt concentration of 3 mg/mL. Under the optimized conditions，linear ranges of safranine T and ponceau 4R were both 4.8-1000 ng/mL. The correlation coefficients were 0.9981 and 0.9987，and the limits of detection were 1.5 and 1.8 ng/mL for safranine T and ponceau 4R，respectively. The limits of quantification were both 4.8 ng/mL. The proposed method was applied to determine ponceau 4R and safranine T in real water samples with acceptable recoveries（88.5%-113.6%）and relative standard deviations（ © 2022, Youke Publishing Co.,Ltd. All rights reserved.