HPCL determination of cyanuric acid in swimming pool waters using phenyl and confirmatory porous graphitic carbon columns

The chlorinated salts of cyanuric acid have found an important role in recr eational swimming pool waters across the United States. Upon application to pool water, they can (1) release disinfectant chlorine or (2) stabilize th e free available chlorine by acting as chlorine reservoirs in the form of c yanuric acid, preventing the photolytic destruction of residual chlorine by sunlight. Recommended levels of the cyanuric acid stabilizer are in the 10 -100 mg/L concentration range according to the National Swimming Fool Found ation (San Antonio; TX). Two isocratic HPLC methods with UV detection (213 nn) employing phenyl and porous graphitic carbon (PGC) columns and phosphat e buffer eluents (pH 6.7 and pH 9.1, respectively) were developed to accura tely measure cyanuric acid in swimming pools. The two methods allowed fast separation and detection of the stabilizer in 4 (phenyl) and 8 (PGC) min. B oth methods offered practical sensitivities with method detection limits of 0.07 (phenyl) and 0.02 mg/L (PGC), Neither one of the two methods required the use of sample cleanup cartridges. They exhibit chromatograms with exce llent baseline stability enabling low-level quantitation, Most important, t he PGC column had a useful lifetime of-five months and 500 sample analyses/ column, Eleven pool water samples were fortified with 4.8-50.0 mg/L stabili zer, and the average recovery was 99.8%, Finally, statistical analysis on t he relative precisions of the two methods indicated equivalence at the 0.05 critical level.