Monovalent and Divalent Cations in Tap Water (Etylenediamine EDA)

Chloric acid should be analyzed by ion chromatography for water quality standards in accordance to the Ministry of Health, Labor, and Welfare in Japan. 1mL of Ethylenediamine (EDA) solution (50mg/mL) is to be added into a 1L sample, to prevent the generation of chloric acid through the reaction between chlorous acid and residual chlorine. Monovalent and divalent cations in tap water were analyzed by IC YS-50 .

Sample: 50μL
Cation std. containing EDA 50mg/L

1. Li⁺ 2mg/L
2. Na⁺ 10mg/L
3. NH₄⁺ 10mg/L
4. K⁺ 20mg/L
5. Mg²⁺ 10mg/L
6. Ca²⁺ 20mg/L
7. Ethylenediamine, EDA 50mg/L

Sample: 50μL
Tap water containing EDA 50mg/L

2. Na⁺
3. NH₄⁺
4. K⁺
5. Mg²⁺
6. Ca²⁺
7. Ethylenediamine, EDA 50mg/L

Column       : Shodex IC YS-50 (4.6mmI.D. x 125mm)
Eluent       : 4mM Nitric acid + 1.5mM 18-Crown 6-ether aq./CH3CN=90/10
Flow rate    : 1.0mL/min
Detector     : Non-suppressed conductivity
Column temp. : 40°C