title: Microemulsion electrokinetic chromatography for analysis of phthalates in soft drinks.
abstract: Microemulsion electrokinetic chromatography (MEEKC) is proposed for analysis of di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) in soft drinks. However, the instability of microemulsion is a critical issue. In this research, a novel material, Pluronic® F-127, which has the properties of polymer and surfactant, was added for stabilizing the microemulsion in the MEEKC system. Our data demonstrate that the presence of Pluronic® F-127 (0.05-0.30%) also helps enhance resolution of highly hydrophobic compounds, DBP and DEHP. The electrokinetic injection of sodium dodecyl sulphate (SDS) including sample (-10 kV, 20 s) was introduced in this MEEKC system and this yielded about 25-fold sensitivity enhancement compared with hydrodynamic injection (1 psi, 10 s). During method validation, calibration curves were linear (r≥0.99), within a range of 75-500 ng/mL for DBP and 150-1000 ng/mL for DEHP. As the precision and accuracy assays, absolute values of relative standard deviation (RSD) and relative error (RE) in intraday (n=3) and interday (n=5) observations were less than 4.93%. This method was further applied for analyzing six commercial soft drinks and one was found containing 453.67 ng/mL of DEHP. This method is considered feasible for serving as a tool for analysis of highly hydrophobic molecules.
authors.affiliation: School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Taiwan.
authors.forename: Sung-Yu
authors.initials: SY
authors.lastname: Hsieh
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Wang
authors.forename: Shou-Mei
authors.initials: SM
authors.lastname: Wu
mesh_terms: D002253:Carbonated Beverages / Q000032:analysis*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D010795:Phthalic Acids / Q000032:analysis*
chemical_list: D010795:Phthalic Acids
keywords: Microemulsion electrokinetic chromatography; Phthalate; Pluronic® F-127