An HPLC method with UV detection, pH control, and reductive ascorbic acid for cyanuric acid analysis in water

Area of Science:

• Analytical Chemistry
• Environmental Chemistry

Background:

• Cyanuric acid (CA) and chlorinated isocyanurates are produced in large quantities annually.
• These compounds are widely used in household and industrial cleaning products, sanitizers, and as chlorine stabilizers.

Purpose of the Study:

• To develop and optimize a method for the accurate quantification of cyanuric acid (CA).
• To address limitations of previous analytical methodologies for CA determination.

Main Methods:

• High-performance liquid chromatography (HPLC) with UV detection at 213 nm.
• Effective pH control of the eluent (95% phosphate buffer: 5% methanol, v/v) within a narrow range of 7.2-7.4.
• Use of ascorbic acid to suppress complex equilibria of chlorinated isocyanurates, ensuring analysis focused on CA.

Main Results:

• The developed HPLC-UV method demonstrates reproducibility.
• Linear concentration range for CA measurement is 0.5-125 mg/L.
• Method detection limit for CA in water is 0.05 mg/L.

Conclusions:

• The optimized HPLC-UV method provides a reliable and sensitive means for cyanuric acid analysis.
• Effective pH control is crucial for accurate CA determination, avoiding issues like keto-enol tautomerism and interferences.
• The method supports the accurate monitoring of CA in various water matrices.