Study on a new method for determining trace amounts of manganese(II) in water by flow-injection catalytic kinetic spectrophotometry

An on-line supported flow-injection catalytic kinetic spectrophotometry new method for the determination of trace amounts of manganese(II) in water was developed. The method is based on the significant catalytic action of trace manganese on the fading reaction of potassium periodate and magneson I in the presence of nitrilotriacetic acid. The chemical and flow injection variables were optimized. The absorbance intensity was registered in this reaction solution at 560 nm. Under the optimum conditions, a standard curve with good linearity and broad linear range can be obtained in the range of 20-200 mu g.L-1, the linear equation is H(mV)=0.170 5c(mu g.L-1)+0.125 2(r=0.999 3), the detection limit is 1.3 mu g.L-1, the relative standard deviation is 3.57% (n=8), and the sampling frequency is 15 samples per hour. The interference of foreign iron was studied. Satisfied results were achieved with the proposed method to analyze the Mn(II) in river water, waste water and pond water, and the range of recovery was 96%-102%. This method is simple, rapid, sensitive, accurate, highly selective and suitable for automatic and continuous analysis.