Electrochemiluminescent behaviour of vitamin B-1 (thiamine) and tris(2,2 '-bipyridyl) ruthenium in a flow system

Abstract

Upon the electrochemical oxidation of tris(2, 2' - bipyridyl) ruthenium(II) [Ru(bpy)(3)(2+)] and vitamin Bl(thiamine) in 0.1 mol/L NaOH (aqueous solution), a bright electrochemiluminescence (ECL) was observed. Vitamin B1 was transformed into a yellow pseudo - base and a colorless thiol formed when treated with 0.1 mol/L NaOH for 5 and 20min, respectively. The thiol form was oxidized at + 0.88 V(vs.Ag/AgCl) to produce a free radical, which reacted with Ru(bpy)(3)(3+) at a glassy carbon electrode. The light emission at wavelength 609nm was caused by the transition of the excited state of Ru(bpy)(3)(2+) to its ground state. The pH of solution effected the hydrolysis of vitamin B1, which caused the different light emission intensity of Ru(bpy)(3)(2+) and vitamin B1 solution. ECLs of some coexisting substances such as amino acids, sugars, hydroxyl carboxylic acids, vitamin Bz, Bg were also detected in this now system.