An All-in-One Optical Emission Platform for On-Site Sensitive Detection of Selenium in Selenium-Enriched Food: Integrating Digestion, HS-SPME, and Microplasma OES

Abstract The narrow margin between selenium (Se) deficiency and toxicity demands rapid and reliable methods for monitoring Se levels in Se-enriched foods. In this work, we present an all-in-one optical emission platform that integrates in situ sample digestion, derivatization with sodium tetraethylborate, headspace solid-phase microextraction (HS-SPME), and detection via a 3D-printed point discharge optical emission spectrometer (PD-OES) for the quantification of trace Se in food samples. The system incorporates a multisample digestion module capable of processing up to seven samples simultaneously, achieving digestion efficiencies ranging from 84.7% to 96.5%. A built-in microcomputer performs real-time data acquisition, spectral processing, and result output, enabling field operation. A limit of detection of 0.6 μg L–1 (12 μg kg–1) and a limit of quantification of 2.0 μg L–1 (40 μg kg–1) were achieved, representing a 41-fold improvement in sensitivity over conventional direct headspace introduction. The analytical accuracy of the proposed platform was demonstrated by the determination of Se in Certified Reference Materials. Furthermore, the analytical results obtained for Se-enriched cereals, their processed products, and Se-enriched eggs were in excellent agreement with those obtained by microwave digestion coupled with inductively coupled plasma mass spectrometry (ICP-MS). With its compact size (22.1 × 20.6 × 13.3 cm), lightweight (2.4 kg), low energy consumption (25 W), and field-ready operation, this platform offers a practical solution for rapid, sensitive Se determination in food matrices, effectively bridging the gap between laboratory-grade performance and on-site analytical capability.