Polyhedral Oligomeric Silsesquioxane–Based Hybrid Monolithic Column On-line In-Tube Solid-Phase Microextraction Coupled with High-Performance Liquid Chromatography for the Determination of Five Phthalate Esters in Bottled Water

In this study, a convenient and sensitive method for the determination of phthalate esters (PAEs) in plastic bottled water was proposed by on-line in-tube solid-phase microextraction (IT-SPME) coupled with high-performance liquid chromatography (HPLC). A hybrid monolithic column was synthesized with octamethacrylate substituted polyhedral oligomeric silsesquioxane (POSS-MA) as cross-linker and N-butyl methacrylate (BMA) as functional monomer, which was utilized as the extraction phase of IT-SPME. A number of important extraction parameters were systematically optimized, such as sampling flow rate, desorption solvent flow rate and volume, sample volume, and sample pH value. Under the optimal experimental conditions, the linear ranges of five PAEs were in the range of 0.1–60 ng mL−1. The limits of detection were between 0.052 and 0.10 ng mL−1, and the limits of quantification were less than 0.33 ng mL−1. In addition, the intra-day and inter-day relative standard deviations of the method were 0.98–3.0% and 2.0–4.3%, respectively. The EFs of the method for five PAEs were more than 538. The proposed method was also successfully applied to analyze trace PAEs in real samples with good recoveries. The recoveries of this method ranged from 84.6 to 111.6% and the relative standard deviations were less than 4.5%. The extraction recoveries of the prepared hybrid monolithic column of the target PAEs did not decrease significantly within 60 cycles. The results showed that the on-line IT-SPME-HPLC method was sensitive, highly efficient, and operationally convenient.