New ionic liquid modified polymeric microspheres for solid-phase extraction of four Sudan dyes in foodstuff samples.

The new ionic liquid modified polymeric microspheres (ILPM) were synthesized by precipitation polymerization using 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) as the functional monomer, divinylbenzene (DVB) as the cross-linker, and a mixture of toluene and acetonitrile as the dispersant solvent. The obtained ILPM showed good adsorbability to the four kinds of Sudan dyes and were successfully applied as a special sorbent of solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC) for the simultaneous isolation and determination of four Sudan dyes from foodstuff samples. Compared with the traditional SPE adsorbents such as neutral alumina and C18, the ILPM sorbents provided higher recovery with a significant purification effect. Good linearity was obtained in a range of 0.05-4.0 μg/g (r(2) ≥ 0.9996) for the four kinds of Sudan dyes, and the average recoveries at three spiked levels ranged from 92.5% to 106.1% with the relative standard deviations ≤ 5.7%. The proposed ILPM-SPE-HPLC method could be potentially applied to rapid isolation and determination of Sudan dyes in complicated food samples.