Molecularly imprinted solid-phase extraction coupled with HPLC for the selective determination of monobutyl phthalate in bottled water

Analysis and remediation of phthalates in aquatic matrices: current perspectives

Phthalic acid esters (PAEs) are high production volume chemicals used extensively as plasticizers, to increase the flexibility of the main polymer. They are reported to leach into their surroundings from plastic products and are now a ubiquitous environmental contaminant. Phthalate levels have been determined in several environmental matrices, especially in water. These levels serve as an indicator of plasticizer abuse and plastic pollution, and also serve as a route of exposure to different species including humans. Reports published on effects of different PAEs on experimental models demonstrate their carcinogenic, teratogenic, reproductive, and endocrine disruptive effects. Therefore, regular monitoring and remediation of environmental water samples is essential to ascertain their hazard quotient and daily exposure levels. This review summarises the extraction and detection techniques available for phthalate analysis in water samples such as chromatography, biosensors, immunoassays, and spectroscopy. Current remediation strategies for phthalate removal such as adsorption, advanced oxidation, and microbial degradation have also been highlighted.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Heat-shrink tubing as a solid-phase microextraction coating for the enrichment and determination of phthalic acid esters

Heat-shrink tubing, which shrinks in one plane only (its diameter) when heated, commonly used for sealing protection in electrical engineering, was found to be able to function as a solid-phase microextraction coating. Its utility was demonstrated for the determination of phthalic acid esters in an aqueous solution combined with high-performance liquid chromatography equipped with a UV absorbance detector. The preparation procedure was rather simple and only ∼10 min was needed. The fiber cost is extremely low (∼10 cent each). The parameters affecting the extraction were optimized. Heat-shrink tubing fiber exhibited a significant enrichment effect for the three examined phthalic acid esters and up to 931-fold enrichment factor was obtained. The limit of detection was <10 μg/L for all analytes. The operation repeatability and fiber-to-fiber reproducibility were 1.2-8.3 and 5.4-9.1%, respectively. It was successfully applied for the analysis of bottled drinking water with recoveries ranging from 90.1-100.5%.

Rapid and molecular selective electrochemical sensing of phthalates in aqueous solution

Reported research work presents real time non-invasive detection of phthalates in spiked aqueous samples by employing electrochemical impedance spectroscopy (EIS) technique incorporating a novel interdigital capacitive sensor with multiple sensing thin film gold micro-electrodes fabricated on native silicon dioxide layer grown on semiconducting single crystal silicon wafer. The sensing surface was functionalized by a self-assembled monolayer of 3-aminopropyltrietoxysilane (APTES) with embedded molecular imprinted polymer (MIP) to introduce selectivity for the di(2-ethylhexyl) phthalate (DEHP) molecule. Various concentrations (1-100 ppm) of DEHP in deionized MilliQ water were tested using the functionalized sensing surface to capture the analyte. Frequency response analyzer (FRA) algorithm was used to obtain impedance spectra so as to determine sample conductance and capacitance for evaluation of phthalate concentration in the sample solution. Spectrum analysis algorithm interpreted the experimentally obtained impedance spectra by applying complex nonlinear least square (CNLS) curve fitting in order to obtain electrochemical equivalent circuit and corresponding circuit parameters describing the kinetics of the electrochemical cell. Principal component analysis was applied to deduce the effects of surface immobilized molecular imprinted polymer layer on the evaluated circuit parameters and its electrical response. The results obtained by the testing system were validated using commercially available high performance liquid chromatography diode array detector system.

Metal assisted approach to develop molecularly imprinted mesoporous material exhibiting pockets for the fast uptake of diethyl phthalate as copper complex

A new molecularly imprinted mesoporous material (MIM) containing specific pockets for the extraction of diethyl phthalate (DEP) as copper complex has been prepared for the first time. The mesoporous material was developed by utilizing copper-phthalate complex (Cu-DEP) as the template molecule, 3-aminopropyltriethoxysilane (APS) as a functional monomer and tetraethoxyorthosilicate (TEOS) as the silica source for polymer network formation. The mesoporous material showed fast uptake kinetics, and equilibrium was obtained within 30 min due to the introduction of copper, which provides an additional site for interaction with the functional monomer. Synthesized polymer was well characterized using UV-Vis spectrophotometry, IR spectroscopy, TGA studies, and TEM. To achieve efficient extraction of the template molecule, various factors including sorption kinetics, quantity of MIM, time required for equilibrium set-up, sorption isotherm and reuse of MIM were optimized. The extracted DEP samples were analyzed quantitatively at 310 nm using an HPLC-DA system. The prepared material is robust and can be reused. In addition, it was found to be selective for DEP as compared to other phthalates.

Synthesis and Evaluation of Molecularly Imprinted Polymer for the Determination of the Phthalate Esters in the Bottled Beverages by HPLC

A molecularly imprinted polymer (MIP) was prepared in acetonitrile by bulk polymerization, using di-n-octylphthalate (DOP) as a template molecular,α-methacrylic acid (MAA) as a functional monomer, and ethylene dimethacrylate (EDMA) as a crosslinker. Characterization and evaluation of the prepared MIP were carried out by scanning electron microscope (SEM), infrared absorption spectroscopy (IR), and the Scatchard analysis, respectively. Through the optimization of washing solvent, eluting solvent amount, flow rate of loading solution, and loading sample volume, an analysis method was established for DOP related compounds with high selectivity and sensitivity by using the selective molecularly imprinted solid-phase extraction (MI-SPE) technique. Moreover, under the optimal conditions, the extraction effects were comparatively investigated by using MIP cartridge, NIP cartridge, and the commercial PLS cartridge used especially for phthalic acid esters (PAEs), respectively. The results showed that the recoveries of spiked PAEs are in the range of 90.4%–97.8% with the relative standard deviation (RSD) of 1.6%–3.8% on the resulted MIP cartridge, whilst lower recoveries were obtained ranging from 80.2% to 88.9% with an RSD of 1.4%–5.2% on the commercial PLS cartridge.