It was found that noradrenaline and L-dopa could be oxidized by soluble oxygen under the catalysis of polyphenol oxidase (PPO) in mushroom tissue column to produce corresponding tri- or di-hydroxyindole derivatives in basic condition, which can emit strong fluorescence radiation. Based on it, a novel, simple and reagentless mushroom tissue-based fluorescence system combined with flow injection analysis for the determination of noradrenaline and L-dopa is proposed. The fluorescent intensity is linear with the concentrations of noradrenaline in the range of 6×10^-8～1×10^-5 g·mL^-1 and L-dopa in the range of 3×10^-8～1×10^-5 g·mL^-1, respectively. The detection limits in turn are 2.0×10^-8 g·mL^-1 (3S/k) and 1.0×10^-8 g·mL^-1 (3S/k) with relative standard deviations of less than 3% (n=11). The reactor was stable for about 14 d and a complete analysis, including sampling and washing, could be performed in 1.5 min. Various interferences from common ions and antioxidants were examined carefully. The proposed system has been applied to the determination of studied substances in pharmaceutical preparations, and results are in accordance with those values by official methods. The experimental results demonstrated the feasibility and reliability of the proposed method.

Key words: fluorescence, flow injection, mushroom tissue, noradrenaline, L-dopa