Abstract: A new fluorescence quenching method for the determination of trace As(V) has been established.Based on the facts that in HCl solution with α,α'-dipyridine.As(V) can catalyze the reaction of H₂O₂ oxidizing 2,3,4,9-tetrahydrogen-9-hydroxy-1,10-anthraquinone(R) to form non-fluorescence complex which cause the fluorescence quenching.Under the optimum condition,the relationship between the △I_f of the emitting intensity and the content of 0.0040~0.400 0 ng/mL As(V) conform to Beer' law.The regression equation of working curve can be expressed as △I_f=11.94+233.7 C_As(V)(ng/mL)(r=0.9994,n=7).The limit detection(LD) is 6.2×10^-13 g As(V)/mL(n=11).The sample containing 0.0040 and 0.400 0 ng/mL As(V) are repeatedly determined for 11 times.RSD are 2.6% and 3.8% respectively.This method has good repeatability,sensitivity and high precision.It has been successfully applied to the determination of trace As(V) in real samples with satisfactory results.The structure of synthesized was determined by¹H-NMR,IR and MS spectroscopy.