A sensitive and selective fluorescence quenching mthod for the determination of Fe2+ with 1,10-phenanthroline was developed.The fluorescence intensity of 1,10-phenanthroline at λex of 266nm and λem of 365nm was constant in the range of pH 4.0 to 10.0 and decreased linearly upon addition of Fe2_ to its solution.This decrease was mainly due to a static quenching effect caused by the formation of a non-fluorescent complex of Fe2+ with 1,10-phenanthroline.The total amount of iron was determined by using hydroxylamine hydrochloride to reduce Fe3+ to Fe2+,The linear range was from 5.0×10-7 to 2.0×10-5mol/L with a detection limit of 2.4×10-8mol/L at 3σ,The quenching constant of Fe2+ to 1,10-phenanthroline was calculated to be (5.70±0.05）×104L/mol at 25℃.Effects of foreign ions on the determination of Fe2+ were investigated.The results of the new method for the determination of iron in tap water and natural water samples were in good agreement with those obtained by graphite atomic absorption spectrometry.
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