Master of Science (MS)
A quality assurance testing of the ECLOX-M™, a rapid water quality indicator used in potential terrorist attacks, was evaluated for its adequacy in nine regional Louisiana water systems. The ECLOX-M™ system uses enhanced chemiluminescence to measure toxicity in water by integration of a mixture of luminol (C8H7O3N3), and an oxidant in the presence of a catalyst enzyme - horseradish peroxidase (HRP). Water samples were tested for chemiluminescence, chlorine content, pH, and arsenic and/or nerve agent/pesticide contamination. In addition, three toxic industrial chemical standards were evaluated (mercury, a volatile liquid mixture, and a volatile gas mixture) and two nerve agent/pesticide standards (atrazine, and a regulated pesticide mixture). Additional tests included: three replicates of each contaminant at two concentration levels; three replicates of each regional water sample; and chemical standard spikes on each water sample. A metal mixture and a volatile organic compound (VOC) mixture were evaluated to determine the machine's sensitivity to chemical mixtures. Lastly, two ECLOX-M™'s were tested simultaneously to determine their precision and accuracy. Testing revealed a significant difference in the inhibition % for the nine regional water samples. A one-way ANOVA and a student T-test revealed a significant difference in inhibition % between concentrations for all chemical standards tested. A trend was seen with chemicals and water samples in which the standard deviation for inhibition % increases as the toxicity of the sample decreases. An additive effect on inhibition % was hypothesized for the chemical mixtures. Instead an inhibitory effect was seen for the metal mixture, and a synergistic effect was seen for the VOC mixture. This suggests that the ECLOX-M™ is not capable of detecting components or interactions between components within a mixture. The simultaneous testing revealed no significant difference between the performances of the two machines. Lastly, there was a significant difference between the regional water sample pH levels, (p ≤ 0.01). It is suggested that water systems with complex water matrices consider using multiple testing methods, as ECLOX-M™ alone is not an accurate indicator of contamination. Detection of added contaminants is difficult to ascertain if clean water produces high light inhibition.
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Coleman, Jessica, "Quality assurance testing of the ECLOX-M in detecting terrorism threats in Louisiana's public drinking water systems" (2004). LSU Master's Theses. 3282.