Method development for determination of genistein in jewel vine Derris scandens by electrochemical method

Abstract

In this work, the in-house screen-printed electrochemical sensor consisted of 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 onto a 0.3 mm-thick plastic substrate by screen-printing of conductive ink through blocking stencil on a woven mesh. The dimension of the sensor 2.5×1.0 cm was received. Only 50 µL of sample solution was required on this device for the determination of genistein concentration by square wave voltammetry. The oxidation peak of genistein appeared with good response in acidic media at a potential of 0.6 V. Moreover, the signal was enhanced by mixing modifying material, cobalt(II) phthalocyanine and graphene, into the conductive carbon ink before screen-printing on a plastic substrate. Under optimized conditions, the linear range was found to be 2.5-150 µM and the detection limit was 1.5 µM for cobalt(II) phthalocyanine modified electrochemical sensor. For graphene modified electrochemical sensor, the linear range was found to be 1-200 µM and the detection limit was 1.0 µM. This proposed method was applied to determine genistein in jewel vine (Derris scandens), a Thai herbal medicine with anti-inflammatory activity, with satisfying results.