Electrochemical determination of gallic acid in Camellia sinensis (L.) Kuntze, Viola odorata L., Commiphora wightii (Arn.) Bhandari, and Vitex agnus-castus L. by MWCNTs-COOH modified CPE

چکیده مقاله

Gallic acid (GA) is the main phenolic antioxidant which has been subjected of
many studies because of its important biological properties including anticancer,
anti-inflammatory and antimicrobial activities as well as free radicals scavenger and
cardiovascular diseases protector. Hereupon, fabricating a selective and sensitive
sensor for GA detection and measurement is an important issue. In this paper, a
carboxylated MWCNTs modified carbon paste electrode (MWCNTs-COOH/CPE)
was successfully fabricated and employed for GA determination. Activating the
carboxylic sites of the MWCNTs carried out in nitric acid solution in an ultrasonic
bath and further studied by field emission scanning electron microscopy (FESEM),
X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The
electrocatalytic oxidation of GA at the MWCNTs-COOH/CPE surface was studied
by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The
GA presented a high electrochemical response on MWCNTs-COOH/CPE at pH 2 in
comparison with the CPE. This sensor showed a linear response range of 0.33 - 196
μM and a detection limit of 17.2 nM (S/N = 3). Furthermore, the designed MWCNTs-
COOH/CPE was successfully applied as an electrochemical sensing system for
GA determination in extracts of Camellia sinensis (L.) Kuntze, Viola odorata L.,
Commiphora wightii (Arn.) Bhandari, and Vitex agnus-castus L., with the estimated
amount of 11.4, 8.9, 11.91 and 2.9 mg L-1 GA in each plant extract, respectively.