Hollow-fiber liquid-phase microextraction coupled with dual-response ratiometric fluorescence for visual detection of...

This study established a novel method that combines hollow-fiber liquid-phase microextraction (HF-LPME) with in-situ fluorescence detection for the enrichment and trace analysis of selenium in real samples. Selenium species were converted to Se(IV), which reacted with 2,3-diaminonaphthalene (DAN) to form SeDAN, a highly fluorescent hydrophobic complex. Toluene containing fluoranthene was used as the acceptor phase in the hollow fiber to extract SeDAN from the aqueous solution. Through orbital shaking, SeDAN was enriched in the acceptor phase and interacted with fluoranthene within the fiber. Under excitation at 384 nm, dual-response ratiometric fluorescence and visual detection were achieved directly. The ratio I₅₄₅/I₄₆₆ exhibited a strong linear relationship with selenium concentration (R² = 0.9992). The detection limit was 6.409 × 10^-5 μg/mL, and the enrichment factor reached 135. This work successfully integrates fluorescence analysis, smartphone-based detection, and liquid-phase microextraction, thereby establishing an intelligent platform for trace selenium analysis in real samples.