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Alkyl p-hydroxybenzoate, also known as parabens, have been added in personal care products as preservatives for many years. Because of its low prices, odorless and difficult hardening, they are used widely. However, the studies show that parabens may contain estrogen activity and carcinogen activity, and they are potential endocrine disruptors. Moreover, complicated environmental matrix leads to lower concentration of parabens. Therefore, developing a highly selective method to extract parabens from environmental water samples is very important.
Molecularly imprinting technology has been used for preparation of polymers and it can be a high selectivity method for the target molecules analysis. According to the interaction between template molecule and functional monomer, it can be divided into pre-organized approach and self-assembly approach. In this study, using self-assembly approach to prepare molecularly imprinted polymer (MIP). Ethyl paraben (EtP) was used as template molecule, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and 2,2’-azobis-isobutyronitrile (AIBN) as the initiator. The molecularly imprinted polymer has been synthesized using suspension polymerization. After polymerization, the polymer was washed by Soxhlet apparatus until no template could be detect. The molecularly imprinted polymer was proved to have a homogeneous spherical structure by SEM.
A solid-phase extraction based on MIP procedure was used to extract four parabens from water samples. The optimal extraction conditions were packing 50 mg MIP and elution with 2 mL methanol, the eluent was dried under nitrogen and reconstituted with 100 μL methanol. The sample was analyzed by UHPLC-QTOF-MS.
The method showed a good linearity in range of 0.15-2 μg/L. The regression coefficients (R2) exceeded 0.994, and the limit of detection (LOD) were a range from 0.040-0.045 μg/L. The method also had good accuracy (recovery 93-105%) and precision (RSD < 9%). In real samples, parabens were detected between 0.17-5.33 μg/L in Taiwan. | en_US |