A hybrid composite based on an imidazolate zeolite framework, graphite, and polylactic acid, housed in a 3D-printed electrode body, for the sensitive determination of the Sunset Yellow dye in beverage samples.
Abstract
The growing demand for portable, low-cost, and high-performance analytical platforms has stimulated the development of disposable electrochemical devices produced through additive manufacturing technologies. In this study, a 3D-printed electrochemical sensor fabricated from a polylactic acid and graphite composite material modified with cobalt zeolitic imidazolate frameworks (ZIF-67) was developed for the determination of the azo dye sunset yellow (SY) in drink matrices. The incorporation of the ZIF enhanced electrocatalytic activity, improving charge transfer and the analytical response. Morphological, spectroscopic, and electrochemical characterizations confirmed the successful modification and functional properties of the sensor. The electrochemical behavior of SY, investigated by cyclic voltammetry, revealed a proton-coupled electron transfer mechanism predominantly controlled by diffusion, with contributions from surface adsorption. The parameters of the square wave voltammetry technique were optimized, showing two linear ranges (1 - 9.7 and 9.7 - 40.7 μmol L-1 to SY) with excellent correlation (R2 ≈ 0.99). The sensor exhibited high detectability, reaching limits of detection and quantification of 19 and 58 nmol L-1, respectively, and high analytical sensitivity (0.138 μA L mol-1 mm-2). The device demonstrated good precision (RSD < 6.0%), excellent reproducibility (RSD < 3.6%), and remarkable long-term stability (1.2% deviation over 45 days). In addition, high selectivity was observed in the presence of potential interferents commonly found in drink matrices. Application to real samples yielded satisfactory recoveries, between 93 and 111%, and concentrations within regulatory limits. Overall, the proposed sensor constitutes a simple, robust, and cost-effective alternative for the electrochemical monitoring of azo dyes in non-alcoholic drink matrices, demonstrating considerable potential for routine analysis and on-site applications.
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