Objectives Objective To explore the method of capillary ion chromatography for the detection ofcommon cations in water.

Methods The characteristics of capillary ion chromatography in the determination ofpotassium, sodium, calcium and magnesium ion in water were studied.

Results Under the optimal flow rate andoptimal concentration of leaching liquid methane sulfonic acid(MSA)at 0.018 mL/min and 28 mmol/L respectively, the peak area repeatability of potassium, sodium, calcium, magnesium ion in standard solution was all < 1%;and when the sample volume was 0.4 μL, the detection limit was < 3 μg/L.

Conclusion The characteristic of the method was good in reproducibility, low in detection limit and high in sensitivity within the linear range incomparison with the traditional ion chromatography, and was also reagent saving and easier in operation.