Research On The Detection Of Freshness And Drug Residues Of Aquatic Products By Electrochemical Sensors Based On MOFs

The molar ratio of trimethylamine（TMA）to trimethylamine oxide（TMAO）in aquatic products can be used as the evaluation standard for the freshness of aquatic products.Ofloxacin（OFL）residues in aquatic products are harmful to human health.High-efficiency TMA,TMAO and OFL detection methods are of great significance.In this study,the electrochemical sensors of Pb-MOFs-PAAS/GCE,Mn-MOFs-MPA/Au,Cd-MOFs-RGO-MPA/Au,based on metal-organic frameworks materials of materialslead-terephthalicacid（Pb-MOFs）,manganese-terephthalic acid-4.4-bipyridine（Mn-MOFs）,and cadmium-terephthalic acid-4.4-Bipyridine-graphene（Cd-MOFs-RGO）,were constructed for the detection of TMA,OFL and TMAO,respectively.The electrochemical sensors based on metal organic framework materials are simple,rapid and sensitive.1.The electrochemical characterization of Pb-MOFs-PAAS/GCE by cyclic voltammetry confirmed its electrocatalytic effect on TMA.The square wave voltammetry was used to investigate its response to TMA.The results showed there is a relationship between the increase in oxidation peak current and the concentration of TMA in the range of 5.00×10^-9mol/L to 6.30×10^-7mol/L with I（μA）=-117.5C（μmol/L）-11.13（R²=0.996）,the detection limit is 2.09×10^-9mol/L.2.The electrochemical characterization of Mn-MOFs-MPA/Au by cyclic voltammetry confirmed its electrocatalytic effect on OFL.The response performance of the modified electrode to OFL was investigated by square wave voltammetry.The results showed that there is a relationship between the reduction peak current and OFL concentrationin the range of 8.00×10^-10mol/L to 1.66×10^-8mol/L with I（μA）=205.4C（μmol/L）+5.549（R²=0.994）,and in the range of 1.66×10^-8mol/L to1.16×10^-7mol/L with I（μA）=78.44C（μmol/L）+7.538（R²=0.995）,respectively.The detection limit is 2.83×10^-10mol/L.3.The electrochemical characterization of Cd-MOFs-RGO-MPA/Au by cyclic voltammetry confirmed its electrocatalytic effect on TMAO.The response performance of the modified electrode to TMAO was investigated by differential pulse voltammetry.The results showed that there is a relationship between the reduction peak current and the concentration of TMAO in the range of 1.30×10^-9mol/L to 6.66×10^-8mol/L with I（μA）=99.21C（μmol/L）+5.759（R²=0.998）,and in the range of 6.66×10^-8mol/L to 6.66×10^-7mol/L with I（μA）=21.19C（μmol/L）+11.52（R²=0.995）,respectively.The detection limit is 4.45×10^-10mol/L.