Based on platinum nanoparticle–embedded raspberry-liked SiO 2 , a sensitive and selective electrochemical sensor was developed for simultaneous determination of eugenol (EU) and methyleugenol (MEU). Raspberry-liked SiO 2 (RL-SiO 2 ) was characterized with open pores on the surface, which can be used as a path for utilizing the inner space fully. So, platinum nanoparticles (Pt NPs) could be embedded in the inner and outer surface of RL-SiO 2 . As a carrier, RL-SiO 2 not only avoided the agglomeration of the Pt NPs but also improved the catalytic performance. Therefore, the prepared Pt NPs@RL-SiO 2 /GCE exhibited excellent electrocatalytic activity for simultaneous determination of EU and MEU; the linearity ranges were 0.50 ~ 60 μmol/L for EU at a working potential of 0.65 V (vs. saturated calomel electrode) and 0.50 ~ 50 μmol/L for MEU at a working potential of 1.10 V; the detection limits were 0.12 μmol/L and 0.16 μmol/L ( S/N =3); and the relative standard deviations (RSDs) were 3.2% and 4.5%, respectively. In addition, Pt NPs@RL-SiO 2 /GCE was successfully applied to the analysis of fish samples; the obtained recoveries were between 92.0 and 107%. Notably, the results conducted on samples were highly consistent with those obtained from high-performance liquid chromatography. It can be concluded that the study provided a simple method for simultaneous electrochemical determination of EU and MEU in fish samples. Graphical abstract
Schematic illustration of the preparation of RL-SiO2@Pt NPs/GCE for simultaneous determination of eugenol and methyleugenol in fish samples.
Qi Jiang,Jian Huang,Baoguo Ma,Zhengcai Yang,Ting Zhang,Xin Wang
TiO 2 @SiO 2 composite microspheres (TS) were prepared by the deposition of TiO 2 on the raspberry-like SiO 2 @polystyrene microspheres (PSS). The hollow microspheres with hierarchical microtopography possess both improved photocatalytic activity and stabilized TiO 2 particle structure. The results of energy dispersion spectrum (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) showed that after calcination, anatase TiO 2 nanoparticles has formed on the raspberry-like PSS template with preferred deposition among interstitials of the drupelet-like structure. The thermal degradation of the polystyrene (PS) core during calcination led to the hollow microspheres. The photocatalytic experiments indicated that the raspberry-like TiO 2 @SiO 2 composite microspheres (TS1-TS3) had higher photocatalytic efficiency than the smooth ones (TS0), due to the hierarchical and hollow structure. The sample TS2 prepared with a moderate ammonia concentration (3 %) not only had relatively more intact hollow spherical structure, but also enhanced photocatalytic activity. The hollow TiO 2 @SiO 2 composite microspheres (TS3) prepared with 4 % ammonia showed the best photocatalytic efficiency. However, the higher ammonia concentration made the drupelet-like structure unstable and the microspheres tend to disintegrate. The raspberry-like microstructure showed a protective effect on the loaded TiO 2 , which resulted in better recyclability with persistent photocatalytic activity. The hierarchical composite microspheres shed light on the potential effective utilization strategy of nano-photocatalyst.
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