Electrochemical Behaviors and Determination of Paracetamol at Multi-walled Carbon Nanotubes and L-Cysteine Co-Assembling Modified Gold Electrode
With the aid of a condensation agent N,N-dicyclohexylcarbodimide(DCC),the open-ended and carboxyl groups terminated multi-walled carbon nanotubes(MCNTs) and L-cysteine(L-Cys) condensation reaction through the carboxyl and amino group,and the function of MCNTs form self-assembled monolayers on gold electrode surface via bond of S-Au.A modified electrode of MCNTs-L-Cys-Au/SAMs-CME by co-assembling on gold electrode surface with MCNTs and L-Cys was prepared and it was characterized with the method of electrochemistry.The electrochemical behaviors of paracetamo1 show that modified electrode has great effort of electrocatalysis oxidation to paracetamol.meantime,the mechanism of electrocatalysis oxidation to paracetamol on modified electrode was studied.The analysis system is composed of electrocatalytic oxidation of paracetamol at MCNTs-L-Cys-Au/SAMs-CME and reduction of permanganate at another platinum electrode.The flow injection irreversible biamperometric analysis method was studied under the applied potential difference of 0 V.In the 0.05 mol/L sulfuric acid,the oxidative peak current increases linearly with the concentration of paracetamol in the range of 2.0×10-6-2.0×10-4mol/L,linear regression equation was i(nA)=8.21×107C+200(r=0.9984,n=9),and in the range of 2.0×10-4-1.0×10-3 mol/L,linear regression equation was i(nA)=2.30×107C+104(r=0.9938,n=4) with a sampling frequency of 90 samples per hour.The detection limit for paracetamol was 1.0×10-6 mol/L(S/N=3) and the RSD for 20 replicate determination of 1.00×10-4 mol/L paracetamol was 2.7%.This proposed method has the advantage of high selectivity and sensitivity.The determination of paracetamol in tablets was achieved with satisfactory results.