New Methods for the Identification and Quantification of Nitrate, Nitrite, and Perchlorate in Natural and Engineered Systems

Abstract

The contamination of water resources by pollutants exacerbates the current challenges related to increased water demand and scarce water supply. Anionic contaminants, such as nitrate, nitrite, and perchlorate, are one such class of pollutants prevalent in agricultural and industrialized societies that pose a threat to water resources. The presence of these anions constitutes an exigent problem in terms of their identification and quantification in both natural and engineered systems. The main objective of this research was to develop efficient and rapid methods for the separation, identification, and quantification of nitrate, nitrite, and perchlorate, anions in aqueous environmental matrices, using a recently introduced ion chromatography-tandem mass spectrometry (IC-ESI-MS/MS) technique. The success of the developed methods was in their ability to detect these contaminants below the health reference levels defined by national and international health organizations. The linearity of the developed methods was reported with a linearity coefficient exceeding 0.9950 and a relative standard deviation error below 10% for a very wide range of concentrations spread over four orders of magnitude [10-2 ppm – 10+2 ppm]. The nitrite method developed showed that nitrite experiences oxidation into nitrate when injected in IC-ESI-MS/MS at the ESI; however this phenomenon do not influence the quantification of nitrite and nitrate in unknown samples containing both anions. For perchlorate, the reduction in biocathode Microbial Fuel Cells (MFCs) and microcosms was identified and quantified, where the results showed 32.3% and 89.6% removal, respectively. Furthermore, the applicability of the CSIA of perchlorate isotopes on the microcosm and MFCs was examined for a potential isotopic fractionation.

Date of Award	Dec 2011
Original language	American English
Supervisor	Farrukh Ahmad (Supervisor)