Effects of Quenching Methods on HAA Determination in Chloraminated Waters

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Journal of the American Water Works Association






American Water Works Association


This study investigated how the determination of haloacetic acid (HAA) in chloraminated samples was affected by use of ammonium chloride (NH4Cl), the chlorine quenching agent recommended in U.S. Environmental Protection Agency Method 552.3. Alternative quenching agents and methods were also examined. Study results showed that using NH4Cl to preserve HAA samples obtained from chloraminated waters may result in positive errors for samples collected at short contact (or residence) time locations. The magnitude of these errors in practical applications will vary depending on several factors, including pH, reactivity of dissolved organic matter and concentration at the point of chloramination, and chlorine/ammonia application. Among various quenching agents or methods tested, sodium arsenite and stoichiometric amounts of sodium sulfate were found to be appropriate for chloramine samples but have some limitations for use in practical applications. Selection of sample quenching and preservation methods for HAA determination in chloramination systems must be carefully evaluated. In addition, better quenching methods for HAA determination in chloraminated waters are needed.