Ion Chromatography Based Isolation and Quantitation of Chloronitramide Anion in Drinking WaterDrinking Water
Oral Presentation
Prepared by J. Thornhill, B. Johnson, J. Fairey
University of Arkansas, 800 W Dickson Street, 4190 Bell, Fayetteville, AR, 72701-4033, United States
Contact Information: [email protected]; 803-262-9375
ABSTRACT
To support our recent discovery of chloronitramide anion as a decomposition product of inorganic chloramines, analytical methods are needed for its isolation from high-salinity mixtures and for quantitation in drinking waters. We have previously demonstrated chloronitramide anion can be quantified by ultra-high-resolution mass spectrometry with a level of quantitation around 1 μg/L, but high capital costs and instrument availability preclude wide scale adoption needed for nationwide occurrence studies. The work detailed in this presentation demonstrates ion chromatography coupled with ultraviolet (UV) absorbance detection can be used to isolate chloronitramide anion from high salinity mixtures to generate standard reference materials and for quantitation at levels relevant to chloraminated drinking waters. Using a Metrohm 850 Professional IC with an 887 Professional UV/VIS Detector and a Metrosep A Supp 7 – 250/4.0 separation column, we successfully separated chloronitramide anion from high concentrations of chloride, nitrite, and phosphate in background waters with salinities approaching seawater. This instrument was also used to quantify chloronitramide anion at a UV wavelength of 254 nm. Eluent strength, column temperature, flow rate, and UV detector settings were optimized to improve separation and achieve low μg/L detection. Chloronitramide anion was separated from other anions with a retention time of approximately 35 minutes and quantified with a detection limit near 5 µg/L, sufficient for the majority chloraminated U.S. drinking water systems. This presentation will detail the IC methods developed for chloronitramide anion and highlight its strengths and limitations.
