Colorimetric speciation analysis of chromium using 2-thiobarbituric acid capped silver nanoparticles

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Chromium ions (Cr(iii) and Cr(vi)) are significant environmental pollutants.
• Developing sensitive and selective sensors for chromium detection is crucial for environmental monitoring.
• Silver nanoparticles (AgNPs) offer unique optical properties suitable for sensor applications.

Purpose of the Study:

• To develop a novel colorimetric sensor for the sensitive and selective detection of Cr(iii) and Cr(vi) ions.
• To utilize 2-thiobarbituric acid (TBA)-capped silver nanoparticles (AgNPs) as a nanoprobe.
• To investigate the interaction mechanism and optimize detection parameters.

Main Methods:

• Synthesis and characterization of 2-thiobarbituric acid (TBA)-capped silver nanoparticles (AgNPs).
• Colorimetric detection of Cr(iii) via AgNPs aggregation, monitored by UV-Vis spectrophotometry.
• Determination of Cr(vi) in the presence of ascorbic acid (AA) as a reducing agent.
• Utilizing FT-IR and transmission electron microscopy (TEM) for characterization and mechanism elucidation.
• Application of EDTA as a masking agent for Cr(iii) determination and optimization of detection ranges.

Main Results:

• A linear relationship was established for Cr(iii) detection (0.012–3.25 mg L⁻¹) with a limit of detection (LOD) of 8.4 µg L⁻¹.
• The sensor showed a distinct color change from yellow to pinkish red upon Cr(iii) interaction.
• Cr(vi) was detected in the concentration range of 0.20–1.40 mg L⁻¹.
• The developed sensor was successfully applied to analyze Cr(iii) and Cr(vi) in cement factory wastewater samples.

Conclusions:

• TBA-AgNPs serve as an effective nanoprobe for a sensitive and selective colorimetric sensor for Cr(iii) and Cr(vi).
• The method demonstrates good performance and applicability for real-world environmental samples.
• This approach offers a promising tool for the rapid and cost-effective monitoring of chromium contamination.