| Based on the improved jet type electrochemiluminescence (ECL) flow injection system,a sensitive method for the determination of melamine in milk power and milk was developed.The experimental conditions of the proposed method,for example pH value,flow rate,injection volume,scan rate and concentration of Ru(bpy)2+3 were optimized.The best results were achieved under the following conditions:running buffer:0.1 mol/L pH 9.5 phosphate buffer,detection reagent:2.5×10-4 mol/L Ru(bpy)2+3,flow rate:20 μL/s,injection volume:100 μL,scan rate:50 mV/s.Under the optimized conditions,the ECL intensity was proporational to the negative logarithmic concentration of melamine in the range of 1.0×10-9-1.0×10-3g/L.The detection limit(S/N=3) was 1.0×10-9 g/L.The recoveries of melamine in milk power and milk at various spiked levels were in the range of 92.2%-114.2% with relative standard deviations (RSDs ) of 0.46%-1.2%The proposed method,with the advantages of sensitivity,easy to operation,and low sample consumption,is expected to be used for the rapid detection of melamine on spot. |