title: Comparison of colorimetric and membrane introduction mass spectrometry techniques for chloramine analysis.
abstract: Three methods for the determination of chloramines in water were compared using pH-buffered nanopure water and natural organic matter (NOM) solutions. We investigated whether the N,N-diethyl-p-phenylenediamine (DPD) colorimetric method and/or an adapted indophenol method (Hach MonochlorF) are suitable for determining the concentration of monochloramine in drinking water. Membrane introduction mass spectrometry (MIMS) was used as a reference analysis method to determine the different chloramine species in water. All methods measured monochloramine accurately in Nanopure water, but the DPD colorimetric method measured higher residuals (inorganic and organic chloramines) than MonochlorF or MIMS when in the presence of NOM due to organic chloramines. The indophenol method (MonochlorF) accurately detected only monochloramine and not other chloramine forms. Overall, the monochloramine concentration measured by MonochlorF was comparable with the MIMS results. A combined chlorine residual approach by the DPD colorimetric method does not differentiate between monochloramine and organic chloramines. Therefore, DPD colorimetric methods can overestimate disinfection efficacy in chloraminated water systems because of interference from organic chloramines that have no or poor bactericidal ability. Compared with the DPD colorimetric method, MonochlorF is a better choice for chloraminated water systems.
authors.affiliation: HDR Engineering Inc., 3200 East Camelback Road, Suite 350, Phoenix, AZ 85018, USA. wontae.lee@hdrinc.com
authors.forename: Wontae
authors.initials: W
authors.lastname: Lee
authors.forename: Paul
authors.initials: P
authors.lastname: Westerhoff
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Chii
authors.initials: C
authors.lastname: Shang
mesh_terms: D002700:Chloramines / Q000032:analysis* / Q000737:chemistry; D003124:Colorimetry / Q000379:methods*; D007215:Indophenol / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D010655:Phenylenediamines; D013997:Time Factors
chemical_list: D002700:Chloramines; D010655:Phenylenediamines; D007215:Indophenol; C013935:N,N-diethyl 4-phenylenediamine; C030816:chloramine