Benzoylecgonine (BE) is the most abundant metabolite of cocaine found in the human body. Analysis of BE in urine by gas chromatography/mass spectrometry is the most common method currently used to detect cocaine abuse. This current method is costly and time consuming, so the investigation of an easier and more cost-effective approach is the goal of this research. Because BE is a zwitterion, it is highly soluble in water and very difficult to extract from urine. Once the pKa values of BE are determined, either the cation or anion form of BE can be formed from the zwitterion by adjusting the pH appropriately. When BE is in a cationic or anionic state, it can be ion-paired with an appropriate counter-ion to form a neutral ion pair. This ion pair can then be extracted into a non-polar solvent, concentrated, and quantitatively determined by UV-Vis spectroscopy.
The following portions of this project have been completed: BE was synthesized, characterized, and purity was verified. Preliminary UV-Vis spectra of BE were measured to determine absorption bands of BE in various solvents. Based on these preliminary UV-Vis spectra, dichloromethane was determined to be the best organic extracting agent. Next, pKa values were experimentally determined, with a PKa1 of 2.15 +/-.01 and a pKa2 of 11.41 +/-.01. The pH of the BE zwitterion solution was adjusted according to these values, and ion pairings and extractions were performed using various ions. Many ion pairs failed to give clear results. There has been some initial success, however, with the ion pair formed between BE and Dragendorf reagent, Bi4-. This ion pair was tested and data gathered in order to generate a clear calibration curve.
Billings '03, Kylee E., "Development of a Simple Method to Detect and Quantify Benzoylecgonine, a Cocaine Metabolite, in Urine" (2003). Honors Projects. Paper 5.