| dc.description.abstract | Alkyl p-hydroxybenzonates( parabens) are highly effective in preventing the growth and spread of bacteria, yeast, and mold. On account of the fact that they are colorless, tasteless, and relatively cheap, parabens are applied to serve as preservative in cosmetics, care products, pharmaceuticals, and foods. On the other hand, a minority of parabens has been shown to cause Contact Urticaria, and parabens has been linked to breast cancer in females. Since direct evidence for parabens causing breast cancer has not been found, however, parabens are not listed in restricted items by the European Union. In the complex matrix of everyday environment, concentrations of parabens are relatively low. As a result, it is important to develop a set of highly selective detection method for parabens in the environment.
Molecular imprinting is an increasingly popular technology for the preparation of specific molecular material with highly selectivity bonding sites. In this study, a self-assembly approach was used. The templates are combined with functional monomers by hydrogen bonds. Ethyl p-hydroxybenzonate( EtP) was used as the template, methylacrylate( MAA) as the functional monomer, ethylene glycol dimethacrylate( EGDMA) as the cross-linker, and azobisisobutyronitrile( AIBN) as the initiator. Together, these chemicals were prepared and mixed with polyvinyl alcohol( PVA) solution and polymerized with suspension polymerization. As the final step, microwave extraction was used to remove the template. The MIP was confirmed as a microspheroidal polymer by scanning the product with an electron microscope.
In this study, MIP was utilized as the selective absorbent of dispersive micro Solid-phase Extraction( D-m-SPE). Four common parabens were extracted from environmental water samples by the high selectivity of MIP, then the identity of the content was determined using Gas chromatography – Mass spectrometry( GC-MS).
The following are optimization conditions of the D-m-SPE: 50 mg of MIP absorbent and 40 ml of real water sample were oscillated by an ultrasonic bath. Next, dry absorbent was obtained by vacuum filtration and back-extracted with 400 μl methyl alcohol. Finally, the obtained solution was injected in GC-MS for detection. In linear range of 0.2-10 μg/ml, the regression coefficients R2 were all above 0.991; the limit of detections ( LOD) were within the range of 0.050- 0.060 μg/ml. The relative standard deviations( RSD) were less than 8% by tests of precision and accuracy. The results showed the stability and reproducibility of this method. The total concentrations of these four parabens in various water samples from Taiwan were ranged from 0.36 to 9.42 μg/L. | en_US |