Determination of Trace Ammonia in Water by Fluorescence Spectrophotometry Combining with Flow-Injection Analysis

A method is described for determination of trace ammonia by fluorescence spectrophotometer combining with flow-injection Analysis. The method is based on the system:in base media,ammonia reacts with o-phthaladehyde(OPA) and 2-mercaptoethanol(ME) producing derivative of indol which has intensive fluorescence. Nonionic surfactant Triton X-100 enhances stability in the system. The optimum reaction condition is investigated. A linear relationship between ammonia concentration and fluorescent intensity is observed over the range 0 1～0 7mg/L with a relative standard deviation(RSD) of 1 3% at ammonia concentration of 0 2 mg/L(n=11). The limit of determination is 0 001 2mg/L.