Development of magnetic micro-solid phase extraction for analysis of phthalate esters in packaged food

A novel, simple and low cost magnetic multi-walled carbon nanotubes-poly (vinyl alcohol) cryogel-micro-solid phase extraction (magnetic-MWCNTs-PVA cryogel-μ-SPE) sorbent was synthesized by incorporating magnetic particles and MWCNTs into a PVA cryogel. The magnetic-MWCNTs-PVA cryogel-μ-SPE sorbent developed, with a large surface area and macro-porous structure, provided good sorbent-to-sorbent reproducibility (%RSD < 8) and each sorbent could be used up to 30 times (%RSD < 6). This sorbent was applied for the extraction of dibutyl phthalate (DBP) and di-2-(ethylhexyl) phthalate (DEHP) in packaged food prior to analysis by gas chromatograph coupled with flame ionisation detector (GC-FID). The concentration of DBP and DEHP in hot-water samples from plastic bags were found in the range 0.04–0.15 μg mL−1 and 0.03–0.20 μg mL−1, respectively, but only DEHP was found in clear chicken soup samples in the range 0.02–0.07 μg mL−1.