Resonance Light Scattering Method And Carbon Quantum Dots Fluorescence Method For Selective Detection Of Perfluorinated Compounds

Perfluorooctane sulfonates(PFOS)and Perfluorooctane acid(PFOA)are two of the most typical perfluorinated compounds(PFCs)which possess the abilities of persistence,bioaccumulation,long-distance migration and carcinogenicity.Herein,it is very important to detect the PFOS and PFOA in the environment.In this work,optical sensors were designed for the detection of PFOS and PFOA based on the resonance light scattering technology and fluorescence spectrophotometry.The mechanism of reaction was also discussed and the proposed methods have been applied to the determination of PFOS and PFOA in real water samples,as follows:(1)This report presents a simple,sensitive and selective victoria blue B(VBB)-based resonance light scattering(RLS)assay of PFOS.In p H 6.0 KH2PO4-Na OH buffer solution,VBB can be protonated and reacts with PFOS by electrostatic interactions to produce ionic-association complexes.Simultaneously,the interaction result in enhanced resonance light scattering intensities greatly,which are characterized by peaks at 277 nm.It is found that the enhanced RLS intensity is proportional to the concentration of PFOS in a range of 0.05 ?M to 4.0 ?M.The limit of detection is 5.0 n M.While,under the optimal experimental conditions,almost no change of the resonance light scattering intensity was observed between VBB and PFOA which is another kind of representative PFCs.The excellent selectivity of PFOS could be due to the hydrophobicity of PFOS higher than PFOA.It is worth noting that the proposed method is capable of differentiating PFOS and some other PFCs.UV/Vis absorption spectrum and scanning electron microscope(SEM)image both were investigated to further validate the reaction mechanism.The interference of coexisting foreign substances and the optimum tests of reaction conditions,including p H value,reaction time,experimental temperature and ionic strength,were also investigated.This method has been successfully applied to the determination of PFOS in environmental water samples with RSD ? 1.74%.(2)In this work,a new carbon quantum dots(CQDs)with orange fluorescence and high fluorescence quantum yield was quickly synthesized through hydrothermal approach method,and then used for detection of PFOS and PFOA in complex water samples,even in vivo.To prepare the CQDs,4-(Diethylamino)salicylaldehyde and phosphoric acid used as reaction precursors were heated together at 200 oC for 1 h in a Teflon-lined stainless steel autoclave.Ultimately,the orange CQDs with the fluorescence quantum yield of 47.1% were obtained.Through analysis of the results,a conclusion can be drawn out that the synergetic effect of strong acid and high temperature could accelerate the rate of hydrothermal reaction.And when adding the PFOS and PFOA(PFOS/PFOA),it is found that there is a strong quenching effect toward the as-prepared CQDs through electron transfer(ET).With the increasing of PFOS/PFOA,the fluorescence intensities at 596 nm are proportional to the concentration of PFOS/PFOA in the range of 0.05-1.0 ?M and 0.1-1.5 ?M,respectively.Moreover,owing to their high chemical stability and stable photoluminescence,the as-obtained CQDs can be applied for the detection of PFOS/PFOA in complex water samples,even in vivo as mentioned above.In consequence,this sensitive assay has a great application prospect in bioanalysis due to its simplicity for PFOS/PFOA detection.