An Electrochemical Platform Based on Graphene Nanoplatelets and Terbium Oxide for Sensitive Detection of Quinoline Yellow in Pharmaceuticals

ABSTRACT A novel electrochemical platform is presented for the sensitive quantification of quinoline yellow, a synthetic dye widely used in food and pharmaceuticals and associated with potential health risks. The electrochemical platform was fabricated through the modification of a glassy carbon electrode (GCE) with terbium oxide (Tb 4 O 7 ) and graphene nanoplatelets (GN). The measurements showed that GCE/GN@Tb 4 O 7 significantly reduces charge transfer resistance and increases the electroactive surface area. GCE/GN@Tb 4 O 7 was first immersed in a quinoline yellow solution for 120 s to allow adsorption of the analyte. GCE/GN@Tb 4 O 7 was then rinsed with 0.1 M PBS and transferred to the voltammetric cell containing only PBS. A distinct oxidation peak at 0.940 V confirmed the superior electrocatalytic activity of the composite compared to GCE and GCE/GN. An adsorption‐controlled and irreversible behavior was observed for the oxidation. The sensor exhibited excellent analytical performance, including a wide linear range (2.0 × 10 −8 –5.4 × 10 −6 M) and a low LOD (1.2 × 10 −9 M). Analysis of tablets yielded 23.9 ± 0.4 µg quinoline yellow with recoveries of 98.8%–101.7%. The electrode demonstrated high repeatability (RSD