Background: Recently, Derris scandens, a Thai herbal medicine with anti-inflammatory
activity, is widely used as beverage and supplementary food. When the traditional medicine is a
choice for health therapy, the simple and reliable equipment is required to control the suitable consuming
amount of the active component.
Objective: To develop the electrochemical sensor for genistein determination in Derris scandens with
high sensitivity and rapid operation.
Method: An in-house screen-printed electrochemical sensor consisting of a three-electrode system
was developed for genistein determination. A silver/silver chloride (Ag/AgCl) reference electrode, a
carbon counter electrode and a carbon working electrode were prepared on a 0.3-mm-thick plastic
substrate by the screen-printing technique using conductive ink. The dimensions of each sensor were
2.5×1.0 cm. Only 50 μL of sample solution was required on this device for the determination of genistein
concentration by rapid response square wave voltammetry.
Results: The oxidation peak of genistein appeared with good response in acidic media at a peak potential
of 0.6 V. Moreover, the signal was enhanced by modifying the conductive carbon ink with cobalt(
II) phthalocyanine. Under the optimized conditions, the linear range was found to be 2.5-150 μM
and the detection limit was 1.5 μM. Moreover, the small volume extraction was successfully developed
without any further pre-concentration. This proposed method was applied to determine genistein
in Derris scandens with satisfying results.
Conclusion: The proposed method is promising as an alternative method for genistein determination
with facile and fast analysis.
Keywords: Cobalt(II) phthalocyanine, Derris scandens, Electrochemical sensor, Genistein, Screen-printing, Square-wave voltammetry
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