In ion chromatography with suppressed conductivity detection, calibration curves quite often are not really linear. Especially, if a calibration has to cover a large concentration range, results will be more accurate when multiple calibration curves for different concentration ranges are applied. The MagIC Net software allows to apply multiple calibration curves within one single determination. This means that for every ion the optimal calibration is applied, improving the accuracy of the results. This method is applied to rainwater samples.