Research Of Carbon Nanomaterials Modified Electrodes For Simultaneous Determination Of Multiple Substances

Due to the excellent mechanical,electrical and chemical properties,carbon nanomaterials have been widely used in the preparation of modified electrodes.In this study,two novel electrochemical sensors based on carbon nanomaterials have been developed for the simultaneous determination of multiple substances.The main contents are as follows:1.Based on commercial nitrogen-doped multi-walled carbon nanotubes(N-MWCNTs),a novel electrochemical sensor was successfully prepared for the simultaneous determination of dopamine(DA)and uric acid(UA)in the presence of ascorbic acid(AA).The morphology of the modified electrode was characterized by scanning electron microscope(SEM).The electron transfer ability of the electrode was detected by electrochemical impedance spectroscopy(EIS).And the catalytic performance of AA,DA and UA at the modified electrode was studied.The results showed that the sensor exhibited good catalytic effect on the oxidation of AA,DA and UA with separated oxidative potentials.The as-prepared sensor can be used for the simultaneous determination of DA and UA in the presence of AA.In the coexisting system of AA,DA and UA,the differences of the oxidation peak potential of AA and DA,DA and UA,AA and UA were 152,133 and 285 mV,respectively.For the simultaneous detection of DA and UA in the presence of AA,the linear ranges were 1.0?1 00.0 ?mol·L-1 and 2.0-400.0 ?mol·L-1,with the detection limits(S/N=3)of 0.1 ?mol·L-1 and 0.3 ?mol·L-1,respectively.The sensor also has the advantages of good stability and reproducibility and simple preparation,and is expected to be used for detection of DA and UA in the real sample.2.In this experiment,GR/MWCNTs/GCE modified electrodes were prepared by drop-casting the mixed solution of multi-walled carbon nanotubes(MWCNTs)and carboxylated graphene(GR)onto the surface of clean glassy carbon electrode.The GR/MWCNTs composites combine the advantages of MWCNTs and GR.The GR/MWCNTs/GCE exhibited excellent catalytic ability to the electrochemical reactions of acetaminophen(AC),hydrochlorothiazide(HCTZ)and L-tyrosine(L-Tyr).The modified electrode can be used for the simultaneous determination of AC,HCTZ and L-Tyr.In ternary mixtures,the differences of the oxidation peak potential of HCTZ and L-Tyr,L-Tyr and AC,HCTZ and AC were 0.197,0.287 and 0.484 V,respectively.For the simultaneous detection of AC,HCTZ and L-Tyr,the linear ranges were 1.0?486.0 ?mol·L-1,2.0?580.0 ?mol·L-1 and 2.0?460.0 ?mol·L-1,with the detection limits of 0.5 ?mol·L-1,0.7 ?mol·L-1 and 0.4 ?mol·L-1,respectively.The sensor also has a good selectivity and reproducibility,and high stability.The as-prepared sensor was used for simultaneous detection of AC,HCTZ and L-Tyr in urine samples,the results were satisfactory.