Onsite quantifying electron donating capacity of dissolved organic matter

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Water Quality Monitoring

Background:

• Electron donating capacity (EDC) of dissolved organic matter (DOM) is crucial for redox processes in various environmental matrices.
• Current onsite quantification methods for DOM EDC are limited in applicability and efficiency.

Purpose of the Study:

• To develop a simple, portable device for accurate onsite measurement of DOM EDC.
• To compare the performance of the new device with existing methods like flow injection analysis (FIA) and mediated electrochemical oxidation (MEO).

Main Methods:

• Development of a portable device utilizing pre-injected [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid), ABTS·+].
• Quantification of EDC in various water samples, including natural and reclaimed waters.
• Comparison of accuracy and efficiency against established MEO and FIA methods.

Main Results:

• The developed device offers a lower limit of quantification (0.2 µmol for Trolox) and a wider DOC concentration range (0.5-20 mg/L) than FIA or MEO.
• Significantly reduced sample preparation and measurement time compared to MEO and FIA.
• Comparable accuracy to MEO for standard humic and fulvic acids; higher molecular weight humic acids exhibit higher EDC.
• Positive correlations found between DOM EDC and chemical oxygen demand, chromophoric DOM, molecular weight, and humification in natural and reclaimed waters.

Conclusions:

• The portable device provides accurate and time-efficient onsite EDC quantification of DOM.
• The method shows promising applications for rapid quality assessment of natural and reclaimed waters.
• Higher molecular weight DOM fractions contribute more significantly to EDC.