Abstract

A prism-coupled surface plasmon resonance (SPR) platform was assessed for detecting dilute acetone in liquid samples representative of condensed exhaled breath. The study combines transfer-matrix Fresnel calculations with wavelength-interrogated experiments performed with a PMMA prism and a nominal 50 nm Au layer. The numerical analysis was used to examine the resonance position, line broadening, minimum reflectance, sensitivity, and figure of merit as a function of optical and material parameters. Experimentally, aqueous acetone solutions spanning 1.8–90 ppm were analyzed. The resonance band shifted systematically toward longer wavelengths as the acetone content increased, and reproducible spectral changes were obtained for concentrations down to approximately 9 ppm using the present optical setup. From the measured spectral slope and baseline fluctuations, the statistical limit of detection was estimated to be close to 1 ppm, whereas the practical limit was governed mainly by spectrometer resolution and low-concentration signal separation. These results establish a reproducible reference for non-functionalized Au/PMMA SPR sensing of acetone in condensed breath-like aqueous media.

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