Colorimetric and Smartphone-Based Dual-Mode Rapid Detection of Congo Red Using Iron Oxide Quantum Dots

Area of Science:

• Environmental Chemistry
• Nanotechnology
• Analytical Chemistry

Background:

• Congo red is a toxic dye posing environmental and human health risks.
• Persistent environmental presence necessitates rapid detection methods.
• Existing detection methods may lack speed, convenience, or on-site applicability.

Purpose of the Study:

• To develop a dual-mode sensing platform for rapid Congo red detection.
• To utilize iron oxide quantum dots (IOQDs) for colorimetric and smartphone-based sensing.
• To provide a convenient, low-cost, and selective method for real-world sample analysis.

Main Methods:

• Synthesis of iron oxide quantum dots (IOQDs).
• Dual-mode detection utilizing UV-vis spectrophotometry and smartphone imaging.
• Analysis of color changes and blue-to-red (B/R) channel ratios for quantification.

Main Results:

• Colorimetric detection showed linearity between 2-50 μM Congo red with a 0.89 μM detection limit.
• Smartphone-based detection demonstrated linearity and a 0.58 μM detection limit.
• The dual-mode method exhibited high selectivity for Congo red over other dyes.

Conclusions:

• IOQDs provide a practical basis for dual-mode Congo red sensing.
• The developed method is rapid, convenient, cost-effective, and suitable for real samples.
• This approach enhances on-site environmental monitoring capabilities for toxic dyes.