Pushing Complexometric Titrations in the Nanomolar Range through Surface-Enhanced Raman Scattering Monitoring.

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Traditional complexometric titrations are limited by sensitivity (μM to mM range) due to colorimetric endpoint detection.
• Atomic instrumental methods replaced older titrations but are often inaccessible in low-resource settings.
• There is a critical need for sensitive, low-cost water quality monitoring tools, especially in remote areas.

Purpose of the Study:

• To develop a sensitive and frugal method for detecting copper (Cu2+) in water using complexometric titration.
• To adapt Surface-Enhanced Raman Scattering (SERS) for monitoring titration endpoints.
• To demonstrate the applicability of SERS-based titrations for environmental monitoring.

Main Methods:

• Revisiting complexometric titration for Cu2+ detection.
• Utilizing Surface-Enhanced Raman Scattering (SERS) for endpoint monitoring.
• Performing titrations with SERS measurements to generate titration curves.

Main Results:

• Achieved sensitivity down to 250 nM for Cu2+ detection, relevant for environmental concentrations.
• SERS titration curves accurately mirrored thermodynamic predictions.
• Demonstrated trueness of 75 ± 1% (coarse) and 96 ± 3% (fine resolution).
• Method is cost-effective (28 euros) and field-deployable with basic equipment (10 keuros instrument).

Conclusions:

• SERS-enhanced complexometric titration offers a sensitive, frugal, and accessible alternative to traditional methods for heavy metal detection.
• This approach addresses the limitations of instrumental methods in resource-constrained environments.
• The technique is suitable for field-based water quality monitoring with moderate chemical training.