Peak shape analysis and noise evaluation in suppressed ion chromatography for ultra-trace analysis

Numerical analysis was used to study the performance of a suppressed ion chromatographic system with on-line preconcentration for ultra-trace ion determination in ultra-pure power plant waters. Peak-shape analysis by the Edgeworth—Cramér series fitting method was applied in order to check non—linear concentration-dependent effects, so as to evaluate the best experimental practice with regard to the linear calibration range. Noise evaluation by Edgeworth-Cramér fitting residuals and Fourier analysis is discussed in order to establish the detection limits. Results of the checks made for strictly linear conditions and determination of the quantification limits for sodium, chloride and sulphate ions are reported.