Fluorometric quantification of natural inorganic polyphosphate

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Bioremediation

Background:

• Polyphosphate is environmentally abundant and crucial for wastewater treatment and bioremediation.
• Existing methods for polyphosphate quantification have significant limitations.
• A direct, accurate quantification method for inorganic polyphosphate in natural samples is needed.

Purpose of the Study:

• To develop and validate a novel fluorometric approach for direct quantification of inorganic polyphosphate.
• To assess the accuracy, sensitivity, and limitations of the new method.

Main Methods:

• Utilized the fluorochrome 4',6-diamidino-2-phenylindole (DAPI) and its interaction with dissolved polyphosphate.
• Quantified polyphosphate in a neutral-buffered freshwater matrix across various concentrations.
• Evaluated chain length dependence and salt interference on fluorescence signals.

Main Results:

• The DAPI-based method accurately quantifies polyphosphate from 0.5-3 microM P (+/-0.03 microM P).
• The method shows no chain length dependence for polyphosphates ranging from 15-130 phosphorus units.
• Salt interference affects shorter chains, but longer chains (45-130 P units) are unaffected up to 10mS/cm conductivity.

Conclusions:

• The DAPI-based fluorometric protocol provides a sensitive and direct method for inorganic polyphosphate quantification.
• The method is applicable to complex natural samples, offering advantages over existing techniques.
• Proper storage of polyphosphate standards is essential for consistent results.