Interference-reduced detection of 1,2-dihydroxybenzene using an acid-tolerant luminescent probe

Plant polyphenols, particularly flavonoids and phenolic acids containing 1,2-dihydroxybenzene structures, are bioactive compounds with health benefits, but their detection in acidic fruit matrices (pH 4-6) remains challenging. Conventional boronic acid-based probes are often limited by their instability in acidic media because ofthe susceptibility of ester linkages to hydrolysis. Meanwhile, although HPLC and LC‒MS techniques offer excellent sensitivity and selectivity, they remain labor-intensive and frequently encounter challenges in mitigating complex matrix interference.

Herein, we developed an interference-reduced detection method for 1,2-dihydroxybenzene using a boronic acid-functionalized long-lived luminescent metal probe (Ir-PIPB). Notably, Ir-PIPB exhibits robust luminescence within the pH range of 4.4-5.6 (characteristic of fruit juice) and achieves satisfactory performance for the detection of epicatechin at concentration as low as 1 μM. Crucially, its long luminescence lifetime (>800 ns) effectively suppresses intrinsic luminescence interference in complex juice matrices, determined by time-resolved emission spectroscopy. Interestingly, by introducing varying coumarin concentrations as fluorescent interferents, we revealed that the delay in the interference-reduction ability of Ir-PIPB requires sample-specific optimization on the basis of matrix complexity.

This study presents an interference-minimized method for detecting 1,2-dihydroxybenzene using a boronic acid-functionalized long-lived luminescent metal probe. This approach offers a robust and reliable pathway for detecting bioactive polyphenols in acidic environments, particularly within complex fruit-based matrices.