Highly Sensitive Detection Of Perfluorinated Compounds In Environmental Water Samples Based On Resonance Light Scattering And Fluorescence Technology

Perfluorinated chemicals(PFCs),which have been widely used in industrial and commercial fields since 1960 s,have been used as surfactants,polymer additives,flame retardants and various household products and so on.PFOA and PFOS are two typical PFCs,and are also the final metabolites of a variety of other PFCs in the environment.They are globally distributed,which have environmental persistence,bioaccumulation,potential toxicity and long-range migration ability,and can be gathered in the environment and organisms.In addition,PFOA and PFOS have higher water solubility than other PFCs,and can be easily spread in water environment.At present,PFOS and PFOA have been found in waste water,surface water,groundwater and tap water.The problem of environmental pollution caused by PFCs has attracted people's attention in recent years,and has been listed in persistent organic pollutants(POPs).Therefore,it is very important and significant to develop an effective method for rapid and sensitive detection of PFCs in environmental monitoring and assessment.In this work,novel assays have been designed based on the resonance light scattering and fluorescence analysis technology for the detection of PFCs.The reaction mechanism and the analytical application in determination of PFCs in environmental water samples were also investigated,as the following:(1)A resonance light scattering(RLS)assay of PFOA based on the interaction with Crystal violet(CV)was reported.In pH 3.23 britton-robinson(BR)buffer solution,PFOA can interact with protonated CV by electrostatic interaction to form ion association resulting in a significant enhancement of the scattering signal peaked at277.0 nm,320.0 nm and 507.0 nm.The intensities of resonace light scattering(IRLS)of the three peaks increase with the increase of PFOA concentration,and the IRLS is proportional to the concentration of PFOA in the range of 1.0 ~ 20.0 ?mol/L(R12=0.9985),0.10 ~ 25.0 ?mol/L(R22=0.9998)and 1.0 ~ 20.0 ?mol/L(R32=0.9971),respectively.With the increasing concentration of PFOA,the IRLS signal peaked at 320.0nm is more sensitive than that of 277.0 nm and 507.0 nm.Therefore,in this experiment,320.0 nm was chosen as the quantitative analysis wavelength.And the limit of detection(LOD)is 11.0 nmol/L.So the RLS analysis method of PFOA has been established.The UV/Vis spectra and Scanning Electron Microscopy(SEM)were used to investigate the mechanism.The experimental conditions were also optimized.The proposed method is rapid,simple,low cost and high sensitivity.It has been successfully applied to the determination of PFOA in tap water and Jialing River water samples.The recovery rate is 91.36% ~ 104.8%,RSD?4.04%.(2)A simple,rapid,and highly selective RLS method for the detection of PFOS has been developed based on the interaction between methyl green(MG)and PFOS.In the BR buffer solution of pH 6.86,PFOS can interact with protonated MG and form ionic association by electrostatic attraction and hydrophobic force resulting in a significant enhancement of the scattering signal peaked at 272.0 nm,330.0 nm and504.0 nm,respectively.And the IRLS is proportional to the concentration of PFOS in the range of 0 ~ 3.0 ?mol/L(R12=0.9999),0 ~ 25.0 ?mol/L(R22=0.9959)and 0 ~ 15 ?mol/L(R32=0.9910),respectively.The IRLS of peak at 330.0 nm is the most sensitive and its linear range is the most wider in the three peaks.Therefore,330.0 nm was chosen as the wavelength of quantitative analysis in this experiment.Based on the above,a RLS method for rapid detection of PFOS was established.And the LOD is 50.0 nmol/L.It was found that only PFOS could be detected in this experiment,and other perfluorinated compounds such as PFOA could not be detected,which promising high selectivity of the proposed assay.The method has been successfully applied to the determination of PFOS in tap water and Jialing River water samples.The recovery rate is 98.81 ~ 107.38%,RSD?4.36%.(3)A simple and highly sensitive fluorescence assay for the detection of trace amounts of perfluorinated compounds(PFCs)was proposed based on the water-soluble CdTe quantum dots(QDs)capped by Cysteamine(CA).It was found that the fluorescence intensity of QDs peaked at 552.0 nm could be quenched by PFOA and PFOS in the pH 3.23 BR buffer solution,and the fluorescence intensities of CA-CdTe QDs decreased linearly with the increase of the concentration of PFOA and PFOS from0 to 10.0 nmol/L and from 0 to 15.0 nmol/L,respectively.The linearities(R12=0.9996 for PFOA,R22=0.9991 for PFOS)are good.The LOD is 32.02 pmol/L(S/N=3)and43.96 pmol/L(S/N=3)for PFOA and PFOS,respectively.Meanwhile,it was found that PFCs could also form complexes with CA-CdTe QDs in acid medium,resulting in a remarkable enhancement of the resonance light scattering(RLS)signal.The enhanced RLS intensities are in proportion to the concentration of PFOA and PFOS in the range of 0 ~ 5.0 nmol/L(R12=0.9973)with a LOD of 47.78 pmol/L(S/N=3)and 0 ~ 5.0nmol/L(R22=0.9992)with a LOD of 56.72 pmol/L(S/N=3),respectively.So,the highly sensitive RLS methods for the rapid detection of PFOA and PFOS was established.The proposed fluorescence method has been successfully applied to the determination of PFCs in water samples.The recovery rate is 95.0 ~ 104.0%,RSD?5.42%.