Evaluation of caffeine content in carbonated and energy drinks using a sensor-modified polyaniline–silver nanoparticles

Abstract

The detection of caffeine (CAF) is essential due to its widespread use and potential health impacts, including effects on sleep and anxiety. In this study, polyaniline (PANI) and PANI doped with silver nanoparticles (AgNPs) were synthesized to effectively detect CAF in beverage samples. The chemically synthesized polymers were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) to investigate their morphological and electrochemical properties. Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were employed to determine CAF concentrations in caffeinated beverages. SEM results revealed that PANI and PANI–Ag films are spherical, with an average diameter of ~100 nm, while TEM analysis showed AgNPs within the PANI–Ag matrix had an average particle size of 5–10 nm. Optimized experimental conditions yielded a linear response for CAF concentrations ranging from 10 to 90 μM, with an R2 value of 0.9935. The detection limit for the PANI–Ag electrochemical sensor was determined to be 0.38 µM (n = 3). This sensor is important for monitoring CAF levels in beverages, contributing to public health awareness and safety, with electrochemical analysis aligning well with labeled values.