Application of single-drop microextraction to the determination of dialkyl phthalate esters in food simulants

A fast and simple method, using static single-drop microextraction (SDME), has been developed to facilitate the identification and quantification of seven dialkyl phthalate esters in the three aqueous food simulants. The simulants were: A, distilled water; B, 3% (w/v) acetic acid/water; and C, 15% (v/v) ethanol/water. The extraction is performed by simply suspending a drop of organic solvent in the aqueous sample using a conventional gas chromatography (GC) microsyringe. Following extraction, the organic phase is withdrawn into the syringe and analyzed by gas chromatography and flame ionization detection (FID). The optimized method yields a linear calibration curve over three orders of magnitude for all the simulants, and method detection limits (MDLs) allowing detection of all the studied compounds at concentrations below migration limits established by the European Union. The accuracy of the SDME method was tested and compared to that of solid-phase microextraction (SPME) by recovery experiments using spiked samples, with results ranging from 85 to 115% in most cases.