Determination of 11 Phthalate Esters in Beverages by Magnetic Solid-Phase Extraction Combined with High-Performance Liquid Chromatography

Background: Beverages can be easily contaminated by phthalate esters (PAEs) during the production, bottling, and transportation processes. It is necessary to determine the contamination level in beverages for assessment of human exposure. Objective: In this study, magnetic solid-phase extraction (MSPE) was combined with HPLC for the determination of 11 PAEs in beverages. Methods: Self-synthesized magnetic multiwalled carbon nanotubes (m-MWCNTs) were used as the adsorbent for PAE extraction. To extract the PAEs, an appropriate amount of m-MWCNTs and NaCl was added to the beverage sample. The mixture was mixed on a vortex mixer, the magnetic sorbent was collected with the aid of a magnet, and the supernatant was removed. Then, the analytes were eluted with n-hexane acetone (1+1, v/v). Finally, the eluent was analyzed by the HPLC method. The separation was accomplished on a Phenomenex Luna-C18 column (250 x 4.6 mm, 5 mu m), and the detection wavelength was set at 225 nm. Results: The linear ranges of the method were 2-300 mu g/L with correlation coefficients greater than 0.9981. The LOD and LOQ were in the range of 0.659-5.33 x 10(-2) mu g/L and 2.20-17.8 x 10(-2) mu g/L, respectively. The recoveries of the method ranged from 79.8 to 114%, with the relative SDs less than 15.8%. The established method has been successfully applied for the determination of 11 PAEs in mineral water, carbonated soft drink, tea beverage, and fruit juice samples. PAEs were detected at 0.246-34.3 mu g/L in these samples. Conclusions: The m-MWCNTs are the satisfactory sorbent for MSPE because of their strong adsorption capacity for PAEs. The established MSPE-HPLC method is rapid, easy, sensitive, green, and cost-effective. It can be applied to the analysis of trace PAEs in plastic bottled beverages. Highlights: Three magnetic nanoparticles (MNPs), including Fe3O4 MNPs, m-MWCNTs, and magnetic graphene oxide, were synthesized, and m-MWCNTs were chosen as the sorbent of MSPE for PAE extraction because of their strong adsorption capacity for PAEs. An MSPE HPLC method has been developed for the analysis of 11 phthalates in plastic bottled beverages. The established method was successfully applied to the analysis of 11 phthalates in four types of beverage samples.