In this paper, the multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs/SPE) was prepared and the MWCNTs/SPE was employed for the electrochemical determination of the antioxidant substance chlorogenic acids (CGAs). A pair of well-defined redox peaks of CGA was observed at the MWCNTs/SPE in 0.10 mol/L acetic acid-sodium acetate buffer (pH 6.2) and the electrode process was adsorption-controlled. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods for the determination of CGA were proposed based on the MWCNTs/SPE. Under the optimal conditions, the proposed method exhibited linear ranges from 0.17 to 15.8 µg/mL, and the linear regression equation was Ipa (µA) = 4.1993 C (×10−5 mol/L) + 1.1039 (r = 0.9976) and the detection limit for CGA could reach 0.12 µg/mL. The recovery of matrine was 94.74%–106.65% (RSD = 2.92%) in coffee beans. The proposed method is quick, sensitive, reliable, and can be used for the determination of CGA.

This article emphasis on the application of the multi-walled carbon nanotubes screen printing electrodes(MWCNTs/SPEs) to reseach of plant active constituent (oleanolic acid, OA) by electrochemistry analytic procedure. The work explores the optimization of reaction conditions of OA. The stoichiometric ratio of OA on DPPH about 1:1, electrochemical redox mechanism and antioxidant activity of OA were obtained by the determination of electrochemical kinetics parameters such as electron transfer numbers (n), propons (m), electron charge coefficient (α), and standard electron transfer rate constant (k s ) are 1, 1, 0.66, 0.53 respectively based on electrochemical behavior at MWCNTs/SPEs. This method is fast, convenient, low-cost, practicable and can be used to the trace amount determination of the content of triterpenes in natural product.

In this paper, carbon nanotubes modified screen-printed electrode (CNTs/SPE) was prepared and the CNTs/SPE was employed for the electrochemical determination of antioxidant substance Chlorogenic acids (CGAs). A pair of well-defined redox peak of CGA was observed at the CNTs/SPE in 0.10 mol∙L-1 acetic acid-sodium acetate buffer (pH 6.2) and electrode process is adsorption-controlled. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) method for the determination of CGA were proposed based on the CNTs/SPE. Under the optimal conditions, the proposed method exhibited linear ranges from 4.73×10-7 to 4.45×10-5 mol∙L-1, the linear regression equation was Ipa(µA) = 4.1993 C (mol∙L-1)+1.1039 (r = 0.9976) and the detection limit for CGA could reach 3.25×10-6 mol∙L-1. The recovery of matrine was 94.74~106.65% (RSD = 2.92%) in coffe beans. The proposed method is quick, sensitive, reliable, and can be used for the determination of CGA.