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RAPID AND SIMPLIFIED HPLC METHOD WITH UV DETECTION, PH CONTROL AND SELECTIVE DECHLORINATOR FOR CYANURIC ACID ANALYSIS IN WATER
Citation:
Cantu, R, O M. Evans, AND A P. Dufour. RAPID AND SIMPLIFIED HPLC METHOD WITH UV DETECTION, PH CONTROL AND SELECTIVE DECHLORINATOR FOR CYANURIC ACID ANALYSIS IN WATER. Presented at American Chemical Society Regional Meeting, Covington, KY, May 16-19, 2000.
Impact/Purpose:
Develop a method to determine the volume of recreational water ingested by relating the quantity imbibed to the level of a chemical biomarker measured in urine.
Description:
Cyanuric acid (CA) and chloroisocyanurates are commonly used as standard ingredients in formulations for household bleaches, industrial cleansers, dishwasher compounds, general sanitizers, and chlorine stabilizers. They are very well known for preventing the photolytic decomposition of chlorine disinfectant. HPLC methods have been favored for CA analysis. However, striking variations in pH (1-10, most in the neutral range 6.7-7.8) and UV detection (196-225 nm) among these methods demand an operational method with pH control, practical sensitivity, and CA retention. This method is now fully developed as CA is measured adequately still using the HPLC-UV technique but with optimum parameters. UV spectra of CA show strong pH dependency with a strong 213 nm absorption at pHs>7. The HPLC setup combined a C18 separation column with 5% methanol/95% phosphate eluents over a wide array of pHs (2-10). Capacity factors were computed from 0.057 to 0.478. Practical sensitivity and intermediate retention were fond at pH 7.3. The complex equilibria of chlorinated isocyanurates in solution (up to 10 species) are eliminated to 2 species (CA and first ion) by dechlorination with ascorbic acid and watEr reaction resulting in chlorine liberation and CA product as confirmed by UV, HPLC-UV and LC-MS techniques. The proposed method exploits fundamental chemical equilibria, reactivity, and optical properties of CA to measure it in the practical 0.5-125 ug/ml range with an MDL of 0.05 ug/ml.