New application of chitosan-grafted polyaniline in dispersive solid-phase extraction for the separation and determination of phthalate esters in milk using high-performance liquid chromatography

Chitosan-grafted polyaniline was synthesized and applied as a sorbent for the preconcentration of phthalate esters in dispersive solid-phase extraction. By coupling dispersive solid-phase extraction with high-performance liquid chromatography and response surface methodology (central composite design), a reliable, sensitive, and cost-effective method for simultaneous determination of phthalate esters including dimethyl phthalate, di-n-butyl phthalate, and di(2-ethylhexyl) phthalate was developed. The morphology of sorbent had been studied by scanning electron microscopy and its chemical structure confirmed by Fourier transform infrared spectroscopy. Under optimum condition, good linearity was observed in the range of 5.0-5000.0 ng/mL. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were 0.1-0.3 and 0.3-1 ng/mL, respectively. The relative standard deviations were less than 8.8%. Finally, this procedure was employed for extraction of trace amounts of phthalic acid esters in milk samples, the relative recoveries ranged from 82 to 103%.