Abstract:
This work describes the development of an electrochemical method based on a novel poly
(diphenylamine-4-sulfonic acid) modified glassy carbon electrode (poly (DPASA/GCE) for
determination of GA in honey samples. The deposition of the polymer film (poly(DPASA) on
surface of GCE was characterized by cyclic voltammetry using a redox probe (Fe (CN) 6
3-/4-
)
complemented with electrochemical impedance spectroscopy. In comparison to the
unmodified glassy carbon electrode, poly (DPASA) modified GCE revealed a well-defined,
sharp oxidative peak with much enhanced peak current and reduced over-potential for gallic
acid. Improved correlation coefficient for the dependence of peak current on the scan rate
(R2=0.999192) than on the square root of scan rate (R2=0.97471) indicated that the oxidation
of GA at poly (PDASA)/GCE was mainly adsorption-controlled. Under optimized condition
the current response of poly (DPASA)/GCE showed linear dependence on the concentration
of gallic acid in the range of 1.0–300.0 µM with a limit of detection and limit of quantification
of 0.00446 and 0.0148 µM, respectively. Spike recovery results in the range 96.97-98.33%
and interference recovery in the range 98.28- 102.08% in the presence of 50-200% of AA and
UA, validated the developed method for determination of gallic acid in honey sample. The
Gallic acid content of the honey samples collected from the three sampling sites was 21.0 µM
(01kebele), 13.07 µM (09kebele) and 2.66 µM (014kebele). The current method had a better
performance for determination of GA in honey sample as compared with recently reported
voltammetric methods, due to its requirement of simple electrode modification step, extremely
low detection limit, provides the least limit of detection, and reasonably wider linear dynamic
range. It was indicating the capable applications of the method for determination of GA in
real samples including honey and food samples.