Upon the electrochemical oxidation of tris(2, 2'-bipyridyl) ruthenium(II) [Ru(bpy)~3^2^+] and vitamin B~1 (thiamine) in 0.1mol/L NaOH (aqueous solution), a bright electrochemiluminescence (ECL) was observed. Vitamin B~1 was transformed into a yellow pseudo-base and a colorless thiol formed when treated with 0.1mol/L NaOH for 5 and 20min, respectively. The thiol form was oxidized at +0.88V (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 B~1, which caused the different light emission intensity of Ru(bpy)~3^2^+ and vitamin B~1 solution. ECLs of some coexisting substances such as amino acids, sugars, hydroxyl carboxylic acids, vitamin B~2, B~6 were also detected in this flow system.

Key words: FLOW INJECTION ANALYSIS, BIPYRIDINE, RUTHENIUM COMPOUNDS, VITAMIN B1, CHEMILUMINESCENCE ANALYSIS, ELECTROLUMINESCENCE