Validating sample preservation techniques and holding times for the approved compliance monitoring methods for haloacetic acids under the US EPA's stage 1 D/DBP rule

Abstract

Haloacetic acids (HAAs), which are formed during the disinfection of drinking waters with chlorine, are regulated by the US Environmental Protection Agency (EPA) under the Stage 1 Disinfectant/Disinfection Byproducts (D/DBP) Rule. Recently, three studies have been reported indicating that low concentrations of HAAs can also be formed during disinfection with chloramines. Methods currently approved for compliance monitoring under the Stage 1 Rule arrest the chlorine-mediated formation of HAAs by adding ammonium chloride, which forms chloramines. Studies were undertaken using an in-process water that favored the formation of HAAs with moderate total organic carbon concentration and high levels of chlorine to investigate the potential formation of HAAs under sample storage conditions. The ammonium chloride-quenched sample did form a small amount of HAAs, but total formation over a period equal to the 14-day sample storage time was less than 2 microg/l, whereas the unquenched samples increased 41 microg/l during the same period. Pour plate studies indicated that chlorinated drinking waters quenched with ammonium chloride are protected from microbial growth, which is an important additional advantage to this preservation scheme. The presence of a combined chlorine residual should prevent microbial degradation of HAAs in samples. These studies support the preservation protocols and the sample storage times promulgated for compliance monitoring under the Stage 1 D/DBP Rule.

Measurement of pollution levels of N-nitroso compounds of health concern in water using ultra-performance liquid chromatography–tandem mass spectrometry

“…For the analysis of drinking water samples, supplementary recovery tests may be necessary to be conducted because, chlorinated water includes residual chlorine that could affect the extraction recovery of analytes. Under these conditions, sodium thiosulfate must be added to reduce residual chlorine in chlorinated water samples (Pepich et al, 2004). Indeed, it…”

Disinfection and Antimicrobial Processes

“…Formation of haloacetic acids can occur during the preservation and storage of drinking water. Pepich et al (2004) added ammonium chloride to quench the freeavailable chlorine in treated surface water and found it to prevent most of the haloacetic acid formation after 28 d of storage. The observed increase in haloacetic acids occurred mostly over the first two days, and was mainly dichloroacetic acids.…”

Effects of quenching methods on HAA determination in chloraminated waters

“…The study also showed that the use of NH 4 Cl as a quenching agent in chloramination kinetic experiments conducted with preformed chloramine resulted in false high HAA concentrations at early reaction times. Although it was previously reported that NH 4 Cl was able to preserve formed HAA during sample storage time, a close examination of the data indicated continued formation of dichloroacetic acid (DCAA) after NH 4 Cl addition, with the DCAA concentration increasing from 3.8 to 7.7 μg/L after 28 days of storage time (Pepich et al, 2004). Other researchers observed an increase of 20% for DCAA concentration after 14 days of storage time in utility samples quenched by NH 4 Cl (Krasner et al, 1989).…”

“…The quenching agents that can be used for chlorinated water samples include ammonium chloride (NH 4 Cl), reducing agents such as salts of sulfite or thiosulfate, and ascorbic acid. NH 4 Cl showed the ability to preserve spiked haloacetic acid (HAA) concentrations in water samples during a sample holding time of two weeks (Krasner et al, 1989), and it provides the advantage of controlling microbial growth in chlorinated samples (Pepich et al, 2004). Suppression of microbial activity in HAA samples is important because some HAA species have been shown to undergo microbial degradation (Baribeau et al, 2005; McRae et al, 2004).…”

“…Chloramines, formed by the reaction of hypochlorite with the ammonium ion, do not react further to produce additional HAA at significant concentrations and protect against microbiological degradation” (USEPA, 2003). Pepich and colleagues (2004) reported that additional formation of HAA in samples quenched with NH 4 Cl during two weeks of holding time was <2 μg/L. The effect of NH 4 Cl on trihalomethane (THM) formation is not a concern because THM formation by chloramines is negligible.…”