A new method for determining trace-level copper ion was proposed based on flow-injection on-line preconcentration and microwave plasma torch atomic emission spectrometry. Optimized determination conditions were as follows: the volume of sample solution for preconcentration was 18 mL, the time and flow rate for the preconcentration were 9.0 min and 2.0 mL/min, respectively; the flow rate and concentration of the eluant (HCl) were 1.0 mL/min and 2.0 mol/L, respectively; the power of microwave was 110W, the flow rate of the carrier gas was 1.6L/min, the flow rate of the working gas (argon) was 0.4L/min, and the excitation wavelength was 324.8nm. Under optimized conditions, determination range of the method was 2-40 g/L(y = 41.727x-5.9883, r=0.9994), its detection limit was 1.0μg/L, relative standard diviation was 2.66% (n=11), and recovery was 96-104%. The method was without complicated operation to the sample pretreatment, its automaticity was good and sensitivity was higher. The approach has been applied successfily to the determination of Cu2+ in water-steam system at power plants.
