Abstract
It was found that a novel iridium complex, [(dpci)2Ir(bvbbi)](PF6) (dpci = 3,4-diphenylcinnoline, bvbbi = N,N′-bivinyester-1H,1′H-[2,2′] bibenzimidazole), with Ce(IV) in the presence of sodium sulfite can induce a great chemiluminescence (CL) emission. More importantly, a rapid and sensitive CL method for the determination of tryptophan coupled with a flow-injection analysis (FIA) technique has been developed based on the inhibition effect of the tryptophan to the CL emission of [(dpci)2Ir(bvbbi)](PF6)-Ce(IV)-SO32− system. Under the optimum conditions, the decreased CL intensity is proportional with the concentration of tryptophan in the range of 5.0 × 10−7 to 2.0 × 10−5 mol L−1, and the detection limit is 8.2 × 10−8 mol L−1 (3σ). The relative standard deviation (RSD) for 11 parallel measurements of 1.0 × 10−5 mol L−1 tryptophan is 2.7%. The proposed method has been applied successfully for the determination of tryptophan in its pharmaceutical formulations. Moreover, the possible inhibition mechanism of tryptophan on [(dpci)2Ir(bvbbi)](PF6)-Ce(IV)-SO32− CL system was briefly discussed.
