Developments in Chromium Emission Spectrophotometry with a Tungsten Coil Atomizer: Separating Chromium Oxidation States
College
College of Arts and Sciences
Department
Chemistry, Physics, Geology, & the Environment
Faculty Mentor
Dr. Clifton Calloway
Abstract
Tungsten coil atomic emission spectrophotometry (tungsten coil AES) is a known, reliable method for quantitative atomic determinations. Recent design upgrades to this technology have increased its potential to perform more sophisticated atomic determinations, such as simultaneous oxidation state detection. A potential application for this new feature is the simultaneous detection of trivalent and hexavalent chromium in water samples. Both chromium oxidation states are naturally present in water, but their toxicities are vastly different. This difference in toxicity makes it necessary to develop experimental methods to distinguish between the two in order to determine the safety of drinking water. Trivalent chromium is the most stable form of chromium; it is nontoxic and has various biological functions in humans, including immune function and insulin binding. Hexavalent chromium, the second most stable form of chromium, is toxic to humans. The separation of chromium oxidation states is an ideal test case for tungsten coil AES due to the large difference in the electronic environments of trivalent and hexavalent chromium. This difference in electron environments should have an effect on the minimum temperature required to volatilize each respective sample. The minimum volatilization temperature is the physical property that will be exploited in experimentation by the creation of temperature ramps that will allow for two separate emission signals. It was established that the minimum volatilization current for trivalent chromium is 7.48 A and that for hexavalent chromium is 7.60 A. Temperature ramps are currently being developed for separation of the two oxidation states.
Honors Thesis Committee
Cliff Calloway, Ph.D.; Maria Gelabert, Ph.D.; Patrick Owens, Ph.D.
Start Date
22-4-2016 12:55 PM
End Date
22-4-2016 1:10 PM
Developments in Chromium Emission Spectrophotometry with a Tungsten Coil Atomizer: Separating Chromium Oxidation States
West Center,Room 217
Tungsten coil atomic emission spectrophotometry (tungsten coil AES) is a known, reliable method for quantitative atomic determinations. Recent design upgrades to this technology have increased its potential to perform more sophisticated atomic determinations, such as simultaneous oxidation state detection. A potential application for this new feature is the simultaneous detection of trivalent and hexavalent chromium in water samples. Both chromium oxidation states are naturally present in water, but their toxicities are vastly different. This difference in toxicity makes it necessary to develop experimental methods to distinguish between the two in order to determine the safety of drinking water. Trivalent chromium is the most stable form of chromium; it is nontoxic and has various biological functions in humans, including immune function and insulin binding. Hexavalent chromium, the second most stable form of chromium, is toxic to humans. The separation of chromium oxidation states is an ideal test case for tungsten coil AES due to the large difference in the electronic environments of trivalent and hexavalent chromium. This difference in electron environments should have an effect on the minimum temperature required to volatilize each respective sample. The minimum volatilization temperature is the physical property that will be exploited in experimentation by the creation of temperature ramps that will allow for two separate emission signals. It was established that the minimum volatilization current for trivalent chromium is 7.48 A and that for hexavalent chromium is 7.60 A. Temperature ramps are currently being developed for separation of the two oxidation states.
