Study On The Detection Performance Of Fluorene Based Polymer Fluorescent Sensor For Conjugated Small Molecules

In this study,two fluorene based polymers with rigid fluorene ring structure in the main chain were used as fluorescent sensors to detect sudan dyes,nitroimidazole antibiotics and haloperidine pesticides.Firstly,In this study,a fluorene based polymer A was introduced,which could quench the fluorescence of sudan dyes by hydrogen bonding,π-πstacking,fluorescence resonance energy transfer（FRET）and internal filtration effect（IFE）.The fluorescence quenching response was more than 90%.In ethanol,it can detect sudan dyes in the range of 0-20μmol L^-1,0-20μmol L^-1,0-14μmol L^-1 and 0-18μmol L^-1 in 420 s.The detection limits are2.23μmol L^-1,1.85μmol L^-1,1.34μmol L^-1and 1.83μmol L^-1.In addition,fluorene based polymer A showed good anti-interference performance against sudan dyes in the presence of sugar,amino acid,metal ions and other potential interference substances.The detection accuracy of sudies and sudies was 90%-110%.The results show that the recoveries of Sudan dyes are in the range of 90%-110%and RSD is in the range of 2.2%-3.5%,which indicates that fluorene based polymer A has good accuracy and high precision in the identification and detection of Sudan dyes.This makes fluorene based polymer A have a good practical value in the rapid and efficient identification and detection of Sudan dyes.Secondly,we used fluorene based polymer B to identify nitroimidazole antibiotics.The results show that nitroimidazole antagonists can quench the fluorescence of 5μmol L^-1fluorene based polymer B by more than 80%under the combined action ofπ-πstacking,hydrogen bonding and PET.Moreover,in ethanol and PBS（pH=5,7,10）,it can detect metronidazole（MNZ）and ornidazole（ONZ）in 0-60μmol L^-1,0-35μmol L^-1,0-60μmol L^-1,0-35μmol L^-1,and 0-60μmol L^-1,0-35μmol L^-1,respectively within 600 s,and the minimum detection limits are all lower thanμmol L^-1.At the same time,fluorene based polymer B showed good selectivity and anti-interference performance for nitroimidazole antibiotics in the presence of amino acids,metal ions,sugars,antibiotics and many other interfering substances.The recoveries of nitroimidazole antibiotics were 90%-110%,and the relative standard deviations were between 2.0%-4.0%.It can be seen that the detection of nitroimidazole antibiotics with fluorene based polymer B has good accuracy and high precision.Finally,we used fluorene based polymer B for fluorescence recognition of fluazinam.In this study,it was found that 100μmol L^-1 fluazinam can quench the fluorescence of fluorene based polymer B in the mixed solvent of DMF,DMAC,DMSO and PBS（pH=5,7,10）:DMSO=4:1.And it can detect fluazinam in the range of 0-9μmol L^-1,0-12μmol L^-1,0-28μmol L^-1,0-6μmol L^-1 and 0-6μmol L^-1,respectively,within 600 s,with the lowest detection limits of 0-2.5μmol L^-1.At the same time,fluorene based polymer B showed good selectivity and anti-interference performance for fluazinam in the presence of other pesticides,metal ions,anions and other interfering substances.The recoveries of fluazinam were 90%-110%,and the relative standard deviations were between 1.0%-3.0%.At last,through the analysis of fluorescence generation spectra and UV-Vis absorption spectra of fluazinam and fluorene based polymers,it can be seen that they quench the fluorescence of polymers mainly under the combined action ofπ-πstacking,hydrogen bonding,PET,IFE and FRET.The fluorescence sensor technology has a certain practical application value for the detection of fluazinam pesticide residues.