Makkliang, F; Kanatharana, P; Thavarungkul, P; Thammakhet-Buranachai, C
Phthalate esters (PAEs), especially dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP) are widely used as plasticizers in plastics and polymers. They are not chemically bound and can easily migrate into food and human tissue that comes into contact with these materials. The method developed in this work was applied for the preconcentration and determination of these four phthalate esters that might leach from contact lenses and baby teethers. A novel stir-bead micro-solid phase extractor of chitosan cryogel composited with polypyrrole with a steel wire core was evaluated for the extraction of DMP, DEP, DBP and DEHP before analysis by high performance liquid chromatography (HPLC). Scanning electron micrographs of the polypyrrole-chitosan cryogel beads revealed a high porosity with large surface area. Under the optimum conditions, the developed method provided a good linearity in a concentration range from 10 to 750 ng mL-1 for DMP and from 5.0 to 750 ng mL-1 for DEP, DBP and DEHP. The limits of detection (LOD) were 6.07 ± 0.22 ng mL-1, 4.358 ± 0.097 ng mL-1, 4.408 ± 0.099 ng mL-1 and 3.916 ± 0.053 ng mL-1 for DMP, DEP, DBP and DEHP, respectively, and the method reproducibility was good (n = 6, % RSD < 6.0). DBP and DEHP were detected in two original storage solutions of contact lenses from 13.2 ± 1.1 ng mL-1 to 15.4 ± 1.9 ng mL-1 and from 21.3 ± 1.6 ng mL-1 to 23.5 ± 1.5 ng mL-1, respectively. In the artificial saliva in contact with baby teether samples only DEHP was found, from 4.91 ± 0.31 ng mL-1 to 6.78 ± 0.23 ng mL-1, with good recoveries ranging from 81.3 ± 8.4% to 106.3 ± 5.2%.