ABSTRACT
A sensitive electrochemical sensor for the detection of semicarbazide ( SEM ) based on the glassy carbon electrode modified with carboxylated multi-walled carbon nanotube ( CMWCNTs ) was constructed in this work. The modified materials were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The results showed that the CMWCNTs exhibited a certain degree of changes, such as the appearance of the characteristic peaks of carbon oxygen double bonds in carboxyl group, a decrease in diameter and length and a remarkable reduction of the impedance value. The electrochemical behavior of SEM on CMWCNTs/GCE was investigated by cyclic voltammetry and amperometric i-t curve in 1 mol/L HAc-NaAc buffer solution. An irreversible oxidation peak of SEM appeared at CMWCNTs/GCE. Compared to the bare electrode, the current of the oxidation peak was significantly increased. Under the optimal conditions such as HAc-NaAc solution ( pH 7 ) and scan rate of 0. 1 V/s, the obtained sensor presented linear response to SEM concentration in the range of 5. 0 × 10-6 mol/L-1. 09×10-3 mol/L, the linear regression equation was Ip(μA)=-0. 472+0. 0599C (μmol/L) with linear correlation coefficient of 0. 997. The detection limit was 1. 88×10-7 mol/L. At the same time, the recovery was from 92. 8% to 98. 0% in the test of pork liver samples.
ABSTRACT
A sensitive electrochemical sensor for the detection of semicarbazide ( SEM ) based on the glassy carbon electrode modified with carboxylated multi-walled carbon nanotube ( CMWCNTs ) was constructed in this work. The modified materials were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The results showed that the CMWCNTs exhibited a certain degree of changes, such as the appearance of the characteristic peaks of carbon oxygen double bonds in carboxyl group, a decrease in diameter and length and a remarkable reduction of the impedance value. The electrochemical behavior of SEM on CMWCNTs/GCE was investigated by cyclic voltammetry and amperometric i-t curve in 1 mol/L HAc-NaAc buffer solution. An irreversible oxidation peak of SEM appeared at CMWCNTs/GCE. Compared to the bare electrode, the current of the oxidation peak was significantly increased. Under the optimal conditions such as HAc-NaAc solution ( pH 7 ) and scan rate of 0. 1 V/s, the obtained sensor presented linear response to SEM concentration in the range of 5. 0 × 10-6 mol/L-1. 09×10-3 mol/L, the linear regression equation was Ip(μA)=-0. 472+0. 0599C (μmol/L) with linear correlation coefficient of 0. 997. The detection limit was 1. 88×10-7 mol/L. At the same time, the recovery was from 92. 8% to 98. 0% in the test of pork liver samples.