Abstract
The increasing environmental occurrence of engineered nanomaterials demands analytical strategies that are not only sensitive but also aligned with the principles of Green Analytical Chemistry (GAC). In this work, a simple and environmentally friendly method for the determination of carbon black (CB) nanoparticles is proposed based on the fluorescence quenching of fluorescein. The analytical approach involves the extraction and isolation of CB particles onto nylon membranes, followed by their interaction with a fluorescein probe to generate the analytical response, producing a concentration-dependent decrease in fluorescence intensity. Measurements were carried out using a portable fluorescence spectrometer coupled to a fiber-optic probe, enabling rapid and on-site nalysis while avoiding complex instrumentation. The quenching mechanism was evaluated using Stern–Volmer and Lineweaver–Burk models, suggesting a predominantly static interaction between CB particles and the fluorophore. The method exhibited a linear response within the 4–20 µg mL⁻¹ concentration range, LODs of up to 1.20 µg mL⁻¹ and %RSD values between 8% and 12%, demonstrating satisfactory analytical performance. Its applicability was demonstrated in soil samples, providing reliable recoveries (95–107%). The proposed methodology represents a low-cost and reagent-saving alternative towards portable monitoring of CB in environmental matrices.