▎ 摘　　要

NOVELTY - A chemically modified electrode comprises polished glassy carbon electrode, which is polished successively with poly-gold nanoparticles, L-cysteine, Nafion (RTM: Perfluorinated membrane) and reduced-graphene oxide for modification. USE - Chemically modified electrode for detecting caffeine (claimed) in beverages. ADVANTAGE - The chemically modified electrode has high sensitivity and repeatability, long-term stability and low detection limit, and detects caffeine in beverage with detection limit of 1x 10-9 M by showing better linear relationship with oxidation peak current and without requiring pretreatment steps. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) a method for preparing a chemically modified electrode (2) a use of chemically modified electrode for detecting caffeine.