Author(s)

Qiuxia Wang^1,2, Kris A. Berglund^1,3,4*

¹Departments of Chemical Engineering & Materials Science, Michigan State University, East Lansing, MI, USA.
²Departments of Chemistry, Michigan State University, East Lansing, MI, USA.
³Departments of Food Science & Human Nutrition, Michigan State University, East Lansing, MI, USA.
⁴Division of Chemical Engineering, Lulea University of Technology, Lulea, Sweden.

Fluorescence quenching of pyranine by tryptophan, phenylalanine, and nicotinic acid was investigated by using steady state and time resolved fluorescence spectroscopy. On a comparative basis, nicotinic acid is a very strong quencher of pyranine fluorescence, tryptophan is a moderate quencher and phenylalanine is a weak quencher. The strong quenching is the result of the hydrogen bonding complex between pyranine and amine which existed in both tryptophan and nicotinic acid. Contact complex will form between phenylalanine and pyranine which is the reason of quenching of pyranine by phenylalanine. Associates will form in tryptophan and phenylalanine due to the zwitterion ⁺H₃NRCOO^- or/and hydrogen bond. Higher concentrations favor the formation of aggregates in the supersaturated solution which made the quenching curve different from unsaturated solution dramatically.

Fluorescence Quenching, Pyranine, Solution Structure, Tryptophan

Wang, Q. and Berglund, K. (2016) Pyranine Fluorescence Quenching for the Characterization of Solutions. American Journal of Analytical Chemistry, 7, 43-56. doi: 10.4236/ajac.2016.71005.