Migration of 8 Phthalic Acid Esters from Food Contact Materials by Supramolecular Solvents-Based Dispersive LiquidLiquid Microextraction

Supramolecular solvents (SUPRASs) are nanostructured liquids produced in colloidal solutions of amphiphilic compounds by spontaneous, sequential phenomena of self-assembly and coacervation, which have been already proved as effective extractants of various analytes with different polar ranges in a variety of samples. SUPRASs have intrinsic properties derived from the amphiphilic character of the molecules making up them and their high concentration that render them very attractive for extraction process. In most instances, SUPRASs are reversed micelles formed by mixing an alkyl alcohol or an acid with tetrahydrofuran and water. The size of reverse micelle center pore can be adjusted by changing the ratio of tetrahydrofuran and the macromolecular substances are kept from entering the extraction phase, thereby facilitating the extraction and purification. Their adaption to different microextraction formats, compatibility with separation and detection techniques, low cost, simplicity and quickness make SUPRASs a powerful alternative to traditional organic solvents in analytical extractions. SUPRASs were mainly used in combination with high-performance liquid chromatography (HPLC) coupled to ultraviolet-visible, fluorescence and mass spectrometric detection. Extracts containing the analytes are usully injected directly into the HPLC system where the nanostructures disassemble in the hydro-organic mobile phase and produce surfactant monomers that do not influence the chromatographic behavior of solutes. In this study, a novel method was developed for the determination of the migration of 8 phthalic acid esters (PAEs) from food contact materials using SUPRAS-based dispersive liquid liquid microextraction (DLLME) coupled with isotope dilution ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analytes in food simulants were extracted by a SUPRAS consisted of octanol, tetrahydrofuran and aqueous solution. The key parameters in terms of the type and volume of extractant, amounts of tetrahydrofuran, and vortex time were investigated. The analytes were separated on a Waters Acquity UPLC BEH C18 column (2.1 mm×50 mm×1.7 μm) with gradient elution by methanol and water. The qualitative and quantitative analysis was conducted by ESI-MS in positive ion mode under multiple reaction monitoring (MRM) mode. The experimental results demonstrated that good linearity (r²>0.99) is observed in their respective concentration ranges. The limits of detection (LODs) are 0.1-1.0 μg/L, and the limits of quantitation (LOQs) are 0.5-2.0 μg/L, respectively. The recoveries of PAEs range from 84.8% to 117.5% at three spiked levels with the relative standard deviations (RSDs) between 2.1% and 18.7% (n=6). The proposed method is accurate, reliable, simple and convenient, and is suitable for the determination of migration of PAEs from food contact materials.