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Bachelor of Science
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The development of a highly sensitive detection method for phosphorus is described for the purpose of measuring the concentration of phosphorus in Lake Auburn as an assessment of the water quality. Phosphorus exists in Lake Auburn in concentrations found in the parts per billion (ppb), amounts that are incredibly difficult to detect and require precise techniques. Even though phosphorus concentrations are found at such low levels they still have a significant effect on the lake’s ecosystem. To have an understanding of the cycling of phosphorus, highly sensitive and reliable analytical methods are required. Two analytical chemistry methods, UV-vis spectrophotometry and chemiluminescence, based on the formation of a molybdophosphoric heteropoly acid are tested. The UV-vis spectrophotometric method relies on the formation of a molybdenum blue color proportional to the concentration of phosphate in solution. The regression lines were linear, R2 values > 0.90 for all trials for 2 to 50 ppb. Though the regression lines are linear they vary greatly between each trial which questions their accuracy to measure unknown samples. The chemiluminescence method was based on the formation of a vanadomolybdophosphoric heteropoly acid, followed by chemiluminescence detection with an alkaline luminol solution. A linear regression for the range of 5 to 100 ppb with a R2 value of 0.98. A sample from Lake Auburn was tested with the chemiluminescence method calculating a concentration of 3.552 ppb for orthophosphates. Further testing and polishing of the chemiluminescence method will be necessary but it provides a better estimate for measuring freshwater samples
Kiesler, Hannah Brody, "Measuring Trace Concentrations of Phosphorus in Lake Auburn, ME using UV-Visible Spectrophotometry and Chemiluminescence" (2016). Standard Theses. 118.
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