Synergistic Enrichment and Catalytic Sensing Platform Based on ZIF-8-NH₂/Dynamic Schiff Base Hydrogel for Ultrasensitive Detection of Hydroquinone

Why It Matters

The platform offers a rapid, low‑cost alternative to laboratory‑grade HPLC/GC‑MS for monitoring toxic hydroquinone residues, strengthening food‑safety surveillance. Its portability and stability make it suitable for on‑site testing in supply chains and regulatory settings.

Key Takeaways

• Covalent ZIF‑8‑NH₂ links improve hydrogel stability and conductivity
• OCZN‑30 sensor detects hydroquinone down to 0.0167 µM
• Linear detection range spans 0.05 µM to 1.8 mM
• Recovery rates of 96.3–104.7 % achieved in water and beverages
• Sensor retains >90 % signal after 15 days storage

Pulse Analysis

Hydroquinone (HQ) is a widely used phenolic antioxidant that can leach into food and beverages, posing neurotoxic and genotoxic risks. Traditional monitoring relies on high‑performance liquid chromatography or gas chromatography‑mass spectrometry, techniques that demand expensive instrumentation, extensive sample preparation, and skilled operators. As regulatory agencies tighten permissible limits, the industry seeks portable, cost‑effective tools capable of delivering real‑time data without sacrificing sensitivity.

The breakthrough lies in marrying a dynamic Schiff‑base hydrogel—formed from oxidized sodium alginate (OSA) and carboxymethyl chitosan (CMCS)—with an amino‑functionalized metal‑organic framework, ZIF‑8‑NH₂. The aldehyde groups of OSA react covalently with the amine groups on both CMCS and ZIF‑8‑NH₂, forging a robust three‑dimensional network that eliminates the need for toxic cross‑linkers. This architecture not only densifies the polymer matrix, enhancing mechanical strength, but also exposes abundant Zn‑N Lewis‑acid sites and surface –NH₂ groups that accelerate electron transfer and selectively enrich HQ molecules through hydrogen‑bonding interactions.

Performance testing demonstrates that the OCZN‑30 sensor achieves a detection limit of 0.0167 µM—well below most regulatory thresholds—and maintains linearity across five orders of magnitude. The device exhibits low charge‑transfer resistance, high electrochemically active surface area, and excellent repeatability (RSD < 4 %). Validation in tap water and commercial beverages yields recoveries between 96 % and 105 %, confirming its practical applicability. With a simple drop‑casting fabrication step and stable storage over weeks, this technology positions itself as a viable candidate for field‑deployed food safety monitoring, offering manufacturers and regulators a fast, affordable, and reliable alternative to laboratory‑bound analytical methods.