Extraction and mechanistic investigation of trace dibutyl phthalate using an ionic liquid aqueous two-phase system

Abstract

A novel, economical and sensitive sample pretreatment technique, together with the ionic liquid aqueous two-phase system, was established to extract and determine dibutyl phthalate at trace levels. This technique employed high-performance liquid chromatography coupled with ultraviolet detection. Samples were extracted using a mixture of ionic liquid N-ethyl pyridinium bromide and sodium sulfate salt. The factors affecting extraction, including the amount of components, temperature, pH and extraction time, were optimized. Under the optimized conditions, over 97% of the dibutyl phthalate in standard solution samples could be extracted. The limit of detection and the limit of quantification for the analyses are 0.25 ng mL⁻¹ and 1.0 ng mL⁻¹, respectively, with relative standard deviations ranging from 3.7% to 6.9%. This method was practical when applied to the analysis of dibutyl phthalate in beer, wine and spirit samples, and the recovery of dibutyl phthalate was 91.2–100.4%. The ionic liquid aqueous two-phase system was shown to be much simpler and more environmentally friendly for the determination of trace dibutyl phthalate and for other small biomolecules in water samples.