Molecularly imprinted solid-phase extraction combined with ultrasound-assisted dispersive liquid–liquid microextraction for the determination of four Sudan dyes in sausage samples

A simple and highly selective molecularly imprinted solid-phase extraction (MISPE) combined with ultrasound-assisted dispersive liquid–liquid microextraction (DLLME) was developed for the determination of four Sudan dye (I, II, III, and IV) residues in sausage products. The novel molecularly imprinted microspheres (MIMs) synthesized by aqueous suspension polymerization using phenylamine–naphthol as the dummy template show high affinity to the four Sudan dyes and were applied as selective sorbents of MISPE–DLLME to overcome the drawbacks of template leakage in quantitative analysis. Good linearity was obtained in a range of 0.005–2.0 μg g⁻¹ and the average recoveries of the four Sudan dyes at three spiked levels ranged from 86.3 to 107.5%. The MISPE–DLLME–HPLC protocol significantly improved the purification and enrichment of the analytes and eliminated the template leakage of the conventional MISPE on quantitative analysis.