Rapid Onsite Detection of Fecal Contamination in Water Using a Portable Fluorometric Assay

Area of Science:

• Environmental Science
• Analytical Chemistry
• Biotechnology

Background:

• Fecal contamination of water sources presents significant public health risks.
• Conventional water quality testing methods are often costly, time-consuming, and require specialized expertise, hindering widespread accessibility.
• There is a critical need for rapid, portable, and affordable methods for detecting fecal pollution in water.

Purpose of the Study:

• To develop a portable and rapid fluorometric assay for the detection of urobilin (UB), a key fecal indicator pigment.
• To create a user-friendly 'drop-&-detect' method for on-site water quality assessment.
• To validate the assay's performance against established methods and in real-world water samples.

Main Methods:

• Development of silane-functionalized glass fiber strips impregnated with zinc chloride (ZnCl2) for enhanced urobilin fluorescence.
• Utilized a 3D-printed fluorometer setup with a smartphone camera as the detector for miniaturized optical detection.
• Implemented a rapid assay protocol enabling sub-nanomolar urobilin detection in under one minute.

Main Results:

• The developed assay demonstrated a significantly enhanced fluorescence response for urobilin detection due to ZnCl2 complexation.
• Sub-nanomolar concentrations of urobilin were accurately detected in less than 60 seconds.
• The assay's performance was validated using a benchtop fluorometer and successfully applied to diverse real water samples, including river water and wastewater treatment plant influents/effluents.

Conclusions:

• The portable fluorometric assay provides a rapid, sensitive, and user-friendly method for detecting fecal indicator urobilin in water.
• This 'drop-&-detect' approach, powered by a smartphone, significantly advances field-based water quality monitoring capabilities.
• The method meets the World Health Organization's ASSURED criteria, contributing to global clean water and sanitation goals.