Simultaneous voltammetric determination of droxidopa, acetaminophen, and tyrosine on hematoxylin and graphene oxide/ZnO nanocomposite-modified glassy carbon electrode

Hematoxylin was used in combination with graphene oxide/ZnO nanocomposites as the adhesives for fabricating sensitivity-enhanced electrochemical droxidopa sensor. The electrochemical method showed an excellent character for electrocatalytic oxidization of droxidopa in the presence of acetaminophen and tyrosine. In addition, the experimental parameters such as pH values and the scan rate were optimized. Due to the fine characteristics of modified electrode, a good linear relationship between the anodic peak current and droxidopa concentration in the range 0.075–800.0 μM was observed. The detection limit (3σ) obtained by square wave voltammetry was 4.5 × 10−8 M (S/N = 3). This modified electrode showed excellent selectivity for the determination of droxidopa in the presence of acetaminophen and tyrosine. The prepared sensor was used for determination of droxidopa, acetaminophen, and tyrosine in the real samples.