ABSTRACT
@#An ultrasensitive electrochemical immunosensor modified with graphene and dienestrol(DE)was developed for the detection of dienestrol through indirect competition with K3Fe(CN)6 acting as the redox probes. The results revealed that under optimized conditions a calibration for DE was obtained with a linear range of 500-5 000 ng/mL and the detection limit was up to 0. 2 ng/mL, showing that the proposed electrochemical immunosensor had excellent sensitivity and wide detection range. The immunosensor was examined in real samples for the analysis of DE. A good recovery in the range of 83. 8%-97. 7% was obtained in pork samples.
ABSTRACT
The flower-shaped Pt-Au-graphene oxide ( GO ) nanostructures were synthesized by one-step electrochemical reduction method. The electrocatalytic activities of the nanostructures toward glucose oxidation were investigated by cyclic voltammetry. The results indicated that the nanocomposites exhibited a higher electrocatalytic activity than the Pt-Au nanoparticles. A glucose nonenzyme sensor could be easily developed with the use of the flower-shaped Pt-Au-GO nanostructure. The sensor exhibited low detection limit (4. 0 μmol/L), a wide and useful linear range (1. 0-25. 0 mmol/L), and high sensitivity (26. 3 μA cm-2 ( mmol)-1 ) . In addition, the sensor exhibited excellent reproducibility, stability and selectivity for the determination of glucose, and it could be used to analyze real samples.
ABSTRACT
Graphene ( GN) and multiwalled carbon nanotubes ( MWCNT) composites were coated on glassy carbon electrode ( GCE ) and then poly ( nicotinic acid ) ( PNA ) was electrodeposited on the modified electrode. The electrochemical behavior of pyridoxine hydrochloride ( VB6 ) was investigated at the modified electrode by cyclic voltammetry ( CV ) and differential pulse voltammetry ( DPV ) . Results showed the oxidation current of VB6 at the GN-MWCNT/PNA/GCE was obviously larger than that at GCE, PNA/GCE and GN/MWCNT/GCE. The oxidation process of VB6 was an irreversible diffusion-controlled process involving one electron and two protons. The liner range between the peak current intensity of DPV and the concentration of VB6 was 0 . 05-200 μmol/L with a detection limit of 0 . 02 μmol/L ( S/N=3 ) . The modified electrode showed a good reproducibility with a relative standard deviation of 3 . 1% ( n=8 ) . The proposed method was applied to the analysis of vitamin B6 in vitamin B6 tablets and compound vitamin B tablets with recoveries between 96 . 1%-104 . 5%.