ZnO-CeO₂ hollow nanospheres have been successfully synthesized via the hard templating method, in which CeO₂ is used as the support skeleton to avoid ZnO agglomeration. The synthesized ZnO-CeO₂ hollow nanospheres possess a large electrochemically active area and high electron transfer owing to the high specific surface area and synergistic effect of ZnO and CeO₂. Due to the above advantages, the resulting ZnO-CeO₂ hollow spheres display high sensitivities of 1122.86 μA mM⁻¹ cm⁻² and 908.53 μA mM⁻¹ cm⁻² under a neutral environment for the selective detection of dopamine and uric acid. The constructed electrochemical sensor shows excellent selectivity, stability and recovery for the selective analysis of dopamine and uric acid in actual samples. This study provides a valuable strategy for the synthesis of ZnO-CeO₂ hollow nanospheres via the hard templating method as electrocatalysts for the selective detection of dopamine and uric acid.

Polypyrrole (PPy)-functionalized Fe₃O₄ magnetic nanoparticles (Fe₃O₄–PPy) were prepared and applied as magnetic solid-phase extraction (MSPE) sorbents for the extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. To achieve the optimal extraction performance, several parameters were investigated, including the amounts of sorbent, volume of desorption solvent, extraction and desorption time, inorganic salt and organic solvent content of the sample matrix. Coupled with gas chromatography/mass spectrometry (GC/MS) analysis, a rapid, sensitive and cost-effective method for the analysis of PAHs in aqueous samples was established. The low detection limits (LODs) for the target PAHs in the proposed method were in the range of 0.38 to 5.01 ng L⁻¹, which are much lower than those LODs reported in previous methods. Good linearity of the detection method was obtained with correlation coefficients (R) between 0.9904 and 0.9992. Satisfactory reproducibility was also achieved with relative standard deviations (RSDs) less than 13.3% by an intra- and inter-day precision evaluation. The recoveries of the 10 PAHs in several environmental water samples ranged from 72.4% to 115.7% with the RSDs being less than 9.7%.

A novel boronic acid functionalized magnesia–zirconia (ZM) based material was facile synthesized by Lewis acid–base chemisorption. The elemental analysis, inductively coupled plasma atomic emission spectrometer (ICP-AES) and Fourier transform infrared spectrometer (FT-IR) have proven the successful attachment of 3-aminophenylboronic acid derivative onto ZM surface. In the present work, the affinity of the resulting material towards cis-diols binding was evaluated by using it as the sorbent for solid-phase extraction of 4 nucleosides (namely cytidine, uridine, guanine and adenosine). The results show that such boronic acid modified magnesia–zirconia composite microparticles were excellent for capturing nucleosides in the system with a wide range of pH and high salt concentration, which could be effectively released using TFA–ACN–H₂O (5 : 50 : 45, v/v/v) solution as elution. The 4 nucleosides spiked to untreated urine sample (i.e., no diluting or pH adjustment) were prominently enriched with recoveries in the range of 86–109% and LOD values in the range of 0.003–0.010 μg mL⁻¹. The constructed calibration curves range from 0.05 to 2.0 μg mL⁻¹ showing good linearity correlation coefficient (R ≥ 0.9961) and precision (RSD < 9%). The proposed material would allow for an alternative extraction strategy for identification and quantitative analysis of cis-diols structure compounds in biological samples.