Colorimetric detection of Cr(VI) in water using tetramethyl benzidine (TMB) as an indicator

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Toxicology

Background:

• Hexavalent chromium (CrVI) is a significant environmental and health hazard.
• Existing analytical methods for CrVI monitoring can be complex or lack efficiency.
• There is a need for simple, robust, and efficient methods for environmental CrVI detection.

Purpose of the Study:

• To develop a simple, robust, and efficient colorimetric analytical method for CrVI detection.
• To optimize the method for environmental monitoring applications.
• To validate the method's performance against established regulatory limits.

Main Methods:

• Colorimetric detection of CrVI using TMB (3,3',5,5'-Tetramethylbenzidine) as an indicator in the presence of H2O2.
• Optimization of reaction conditions for CrVI detection.
• Inclusion of EDTA in sample preparation to mitigate interference from other metal ions.
• Validation of the method using fortified water samples and comparison with WHO and US EPA standards.

Main Results:

• The optimized method demonstrated good linearity (r² = 0.9944) with a limit of detection (LOD) of 0.009 mg/L.
• Addition of EDTA improved CrVI recovery (81.73-111.40%) and reduced false positives.
• The EDTA-enhanced method showed excellent linearity (r² = 0.9952) and a detection limit of 0.023 mg/L, below WHO and US EPA limits.
• The method proved effective in natural water samples, indicating potential for real-time environmental monitoring.

Conclusions:

• A simple, efficient, and robust colorimetric method for CrVI detection has been successfully developed.
• The inclusion of EDTA significantly enhances the method's reliability by minimizing interference.
• The developed analytical technique meets regulatory standards for drinking water and shows promise for real-time environmental CrVI monitoring without nanomaterials.