Functional Carbon Nanospheres Used For Determination Of Phenols In Water Samples

Phenolic compounds are pollutants which exist widely in water. Phenolic compounds, a highly toxic compound, is very difficult to be degraded and very easy to be taken into the body through the food chain or skin and mucous membrane to threat the human health. However, because phenolic compounds in water are polar and present in relatively small quantities, the sensitive determination of them has been a hot area of research in the field of food safety.In this study, two kinds of novel functional carbon nanospheres were prepared independently: carboxylated carbon nano-spheres(CNSs-COOH) and aminosilanized magnetic carbon nanospheres(Fe3O4@C-NH2) are used as the solid phase microextraction coating and magnetic solid-phase extraction(MSPE) adsorbent, respectively. Based on the two kinds of carbon materials, the new methods for the determination of phenolic compounds in water are developed. And the developed methods are validated against several real water samples in different locations. The adsorption mechanisms of them are introduced in the paper. The main research results are as follows:1. A novel and simple method for the sensitive determination of endocrine disrupter compounds octylphenol(OP) and nonylphenol(NP) in water samples has been developed using solid-phase microextraction(SPME) coupled with gas chromatography–mass spectrometry. Carboxylated carbon nano-spheres(CNSs-COOH) are used as a novel SPME coating via physical adhesion. The CNSs-COOH fiber possessed higher adsorption efficiency than 100 ?m polydimethysiloxane(PDMS) fiber and was similar to 85 ?m polyacrylate(PA) fiber for the two analytes. Important parameters, such as extraction time, pH, agitation speed, ionic strength, and desorption temperature and time, were investigated and optimized in detail. Under the optimal parameters, the developed method achieved low limits of detection of 0.13~0.14 ng/L and a wide linear range of 1~1000 ng/L for OP and NP. The novel method was validated with several real water samples, and satisfactory results were obtained.2. The high performance separation and enrichment of polar phenols from aqueous matrices is often difficult due to the strong interactions between phenols and water. In this study, carboxylated carbon nano-spheres(CNSs-COOH) were used as a novel coating material in the solid-phase microextraction(SPME) of polar phenols at ultra-trace levels in water samples. Gas chromatography coupled with tandem mass spectrometry(GC-MS/MS) was applied for sample quantification and detection. The novel CNSs-COOH-coated fiber exhibited good thermal stability(>330 ?) and higher extraction efficiency than commercial fibers in the extraction of phenols. The Plackett–Burman design was employed to optimize the extraction factors affecting the extraction efficiency through a response surface methodology. A possible phenol extraction mechanism enabled by the CNSs-COOH-coated fiber is proposed. Under the optimized conditions, low detection limits(0.26~2.63 ng/L), a wide linear range(1~1000 ng/L), good repeatability(2.00~9.02%, n=5) and excellent reproducibility(2.08~8.55%, n=3) were achieved. The developed method was validated against several real water samples, with satisfactory recoveries being obtained each case.3. In this paper, novel aminosilanized magnetic carbon nanospheres(Fe3O4@C-NH2) were designed and fabricated. The structure, surface and magnetic behavior of the as-prepared Fe3O4@C-NH2 microspheres were characterized by elemental analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, and vibrating sample magnetometry. The effects of the experimental parameters were investigated by the Plackett-Burman design, and then the parameters that were significant to the extraction efficiencies were optimized through a response surface methodology. As a novel magnetic solid-phase extraction(MSPE) adsorbent, the micropheres exhibited high adsorption efficiency for bisphenols in water samples. A possible bisphenol extraction mechanism of the Fe3O4@C-NH2 microspheres is also discussed. Under optimal conditions, low limits of detection(0.26–2.63 ng·L-1), and a wide linear range(2 to 3 magnitudes), good repeatability(4.65–7.80 %, n=5) and reproducibility(5.96–8.25 %, n=3) were achieved. The results demonstrated that the Fe3O4@C-NH2 microspheres possess great potential as a novel MSPE adsorbent of bisphenols at trace levels from real water samples.