Determination by Ion Chromatography and Distribution Characteristics of Main Cations in Three Drinking Waters

The concentration of main cations(Li⁺,Na⁺,NH₄⁺,K⁺,Mg²⁺,Ca²⁺,Sr²⁺)in drinking natural mineral water,tap water and surface water samples was measured by ion chromatography(IC)with suppressed conductivity detection. And the concentration levels and distribution characteristics of the cations were discussed. The separation of cations was performed on the separation column IonPac CS 16(5 mm×250 mm)and guard column IonPac CG16(5 mm×50 mm)with 30 mmol/L methane sulfonic acid(MSA)as eluent delivered with flow rate 1.0 mL/min. The column temperature was set as 40 ℃. The results showed that NH₄⁺ was not detected both in drinking natural mineral water and tap water,but it was found(≤1.89 mg/L)in surface water. The detection concentration of Li⁺(≤0.026 mg/L)and Sr²⁺(≤0.263 mg/L)were generally lower in all samples. The average concentration of 7 kinds cations in water samples showed the following order:Surface water>tap water＞drinking natural mineral water.