Carbonate ion is contained in almost all aqueous samples and plays an important role for the ion balance. Therefore, simultaneous analysis of seven common anions (F–,Cl–, NO2–, Br–, NO3–,HPO42-, SO42-) together with carbonate ion can be considered as an important target for development. Previously there have been examples of analysis including a suppressed IC method using NaOH eluent and a non-suppressed IC method using, a polymethacrylate column, but they were not satisfactory enough in peak shape, peak separation and detection sensitivity. The present method uses IC SI-90 4E and allows the baseline separation of seven common anions together with carbonate ion by non-suppressed IC using the eluent, p-hydroxybenzoic acid, pH 8.2.
(Pretreatment with the cartridges packing Na+ type cation exchange resin)
1. Rinse the cartridge with 3mL of methanol and 3mL of H2O separately.
2. Load 3mL of the sample onto the cartridge.
3. Waste 1mL of the first elution.
4. Collect 2mL of the following elution.
Sample: 100μL each:
1. F– 2mg/L
2. HCO3– 20mg/L
3. Cl– 3mg/L
4. NO2– 5mg/L
5. Br– 10mg/L
6. NO3– 10mg/L
7. HPO42- 15mg/L
8. SO42- 15mg/L
Column : Shodex IC SI-90 4E (4.0mmI.D. x 250mm) Eluent : 5mM p-Hydroxybenzoic acid + 5.3mM N,N-Diethylethanolamine aq. Flow rate : 1.5mL/min Detector : Non-suppressed conductivity Column temp. : 25°C