A Field-Portable Fe(IV)-Mediated Competitive Quenching Chemiluminescence Platform with a Synchronous Y-Shaped Flow-through Cell for Broad-Spectrum Quantification of Volatile Phenols

The conventional 4-aminoantipyrine (4-AAP) method for volatile phenols (VPs) fails to detect certain substituted phenols, leading to an underestimation of VPs in water. To overcome this “selectivity blind spot”, we developed an integrated flow-injection analysis chemiluminescence (FIA-CL) platform that quantifies VPs as phenol-equivalent concentrations, providing a more inclusive readout than the 4-AAP method and enabling rapid and reliable monitoring. This sensing mechanism utilizes a competitive reaction where VPs compete with the CL probe (naproxen, NAP) for reactive iron species (Fe(IV)) generated by Fe(II)-activated periodate, resulting in concentration-dependent signal attenuation. Moreover, to address signal loss due to separation between mixing and detection units in conventional FIA-CL systems, we designed a Y-shaped flow-through cell that synchronizes mixing and detection within the same microzone for real-time signal capture. The optimized platform yielded a detection limit of 3.47 μg L –1 with a linear range of 0.011–20 mg L –1, outperforming the 4-AAP method with a 3-fold lower LOD and an 8-fold wider range. Analysis of real water samples showed that VPs concentrations measured by the platform exceeded those obtained by the 4-AAP method, with mass spectrometry confirming that this discrepancy arises from 4-AAP’s failure to respond to certain substituted phenols. Thus, our platform provides a sensitive, broad-spectrum tool for VPs monitoring.