Objective We established a new method for quantitative determination of Cu^2+. Method CuCu^2+could quench the fluorescence intensity of amoxicillin. Based on this reaction, CuCu^2+ was determined by fluorescence spectrophotometry. Results The cooperate reaction between amoxicillin and CuCu^2+ took place, the composition of the complex between CuCu^2+ and amoxicillin was 1:2. The reaction conditions were investigated in detail, The linear range of determination for Cu^2+ was 1.00 ×10^-6-5.00 × 10^-2 mol/L, with detection limit of 1.87×...