A simple colorimetric sensor based on a new deep eutectic solvent for the detection of chromium

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Hexavalent chromium (Cr⁶⁺) poses significant environmental and health risks.
• Accurate and sensitive detection methods for Cr⁶⁺ are crucial for environmental monitoring.
• Existing methods may be complex, costly, or lack selectivity.

Purpose of the Study:

• To develop a selective, sensitive, and affordable colorimetric method for Cr⁶⁺ detection.
• To utilize a novel deep eutectic solvent (DES) for enhanced detection capabilities.
• To validate the method's performance in real-world environmental samples.

Main Methods:

• A colorimetric probe was synthesized using tetrabutylammonium bromide (TBABr), ascorbic acid (AA), and ethylenediaminetetraacetic acid (EDTA) in a DES.
• Cr⁶⁺ was reduced to Cr³⁺ by AA, forming a purple complex with EDTA, which was extracted into the DES phase.
• Quantification was performed using UV-Vis spectrophotometry and smartphone-based image analysis at 550 nm.

Main Results:

• The method achieved a low limit of detection (0.056 μM) and a wide linear range (0.5-100 μM).
• High correlation coefficient (0.9962) and low relative standard deviations (<6%) indicate reliability.
• The sensor successfully detected chromium in water and soil samples, demonstrating practical applicability.

Conclusions:

• The developed DES-based colorimetric sensor offers a simple, sensitive, and cost-effective approach for Cr⁶⁺ determination.
• This method shows great potential for monitoring chromium in various environmental and biological matrices.
• The combination of DES and colorimetry provides a powerful tool for trace metal analysis.