A novel extraction technique i.e. hydrophobic magnetic nanoparticle (MNP)-assisted in situ supramolecular solvent (SUPRAS) microextraction was proposed, and it was applied for the analysis of sulfonamides (SAs) and fluoroquinolones (FQs) in aqueous samples, coupled with high performance liquid chromatography-UV detection (HPLC-UV). In this extraction method, hexafluoroisopropanol-mediated salt-free catanionic surfactant based SUPRAS in situ microextraction was initially carried out; then, the SUPRAS was quickly adsorbed by the hydrophobic magnetic nanoparticles and gathered by an external magnetic field. This can greatly shorten the separation time and overcome the dependence on centrifugation, and also perform a secondary extraction of free analytes (not extracted by SUPRAS) from water samples. The magnetic separation ability of different hydrophobic MNPs was evaluated by adsorbing supramolecular aggregates from the water sample. The effective parameters affecting the extraction efficiency of the analytes were investigated and optimized using the one variable at a time method. About 3 min was required to realize the extraction of analytes with an enrichment factor (EF) of 12–53 for SAs and 79–118 for FQs. Compared with the centrifugation-assisted SUPRAS microextraction, the hydrophobic MNP-assisted SUPRAS microextraction obtained much better extraction and preconcentration efficiency. The proposed novel extraction method with HPLC-UV provided LODs of 0.21–0.76 ng mL−1 for SAs and 0.10–0.18 ng mL−1 for FQs. Good linearity was obtained with correlation coefficients ranging from 0.9962 to 0.9999. The intra- and inter-day recoveries of the target antibiotics were in the range of 92.0–111.3% with RSD% below 10.4%. The method was successfully applied to determine SAs and FQs in real water samples, such as lake water, river water, reservoir water, and wastewater.
Xia Yan,Hang Zhao,Hongyan Song,Jun Ma,Xiaofeng Shi
Surface-enhanced Raman scattering (SERS) has great potential for the detection of marine pollutants, but it is still restricted in ultra-trace and quantitative analysis. Here, a strategy for the detection of polycyclic aromatic hydrocarbons (PAHs) was proposed based on Au nanoscale convex polyhedrons (Au NCPs) coated with high-energy facets and embedded with 4-ATP as a probe molecule. Au NCPs acted as SERS substrates and led to limits of detection (LODs) for six common PAHs that reached 0.01 nM. Using internal calibration, the relative standard deviations (RSD) of the spectral stability and reproducibility were as low as 3.36% and 5.11%, respectively. The maximum mean relative errors (AREs) of the predicted and true values were 6.28%. The results indicate that the resulting Au NCPs improved the ultra-trace and quantitative detection of SERS, thus suggesting that the Au NCPs have practical application value in SERS.
Lanying Xu,Yingying Huang,Bingshan Zhao,Limin Ren,Tao Long
β-Cyclodextrin modified magnetic microspheres were synthesized and used as an effective adsorbent for the solid-phase extraction of three phenols from water samples. Scanning electron microscopy and Fourier transform infrared spectrometry were used to characterize the adsorbents. The major parameters affecting the extraction and desorption efficiencies, such as adsorbent dosage, extraction time, pH, ionic strength, and eluent type were systematically optimized. Under these conditions, three phenols in water samples were extracted and determined by high performance liquid chromatography (HPLC) with diode array detection (DAD). Limits of detection (LODs) of 0.04–0.34 ng mL−1 and limits of quantification (LOQs) from 0.13 to 1.14 ng mL−1 were achieved with good repeatability (relative standard deviation <7.5%). The developed method was applied for the determination of 2,4-dichlorophenol, 2,4-dinitrophenol and bisphenol A in spiked Yangtze River water, and the recoveries were from 81.0% to 94.9%. The results demonstrated that the combination of magnetic solid-phase extraction (MSPE) with HPLC-DAD is suitable for the determination of trace phenolics in environmental water.
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