Carbonate ion is present in virtually all water samples and plays an important role in ion balance. Thus, it is an important task to simultaneously analyze seven common anions (F^-, Cl^-, NO₂^-, Br^-, NO₃^-, HPO₄^2- and SO₄^2-) in the presence of carbonate ion. In this application, IC SI-90 4E, a suppressor type anion column was used. Although SI-90 4E is a suppressor type anion column generally operated with a sodium carbonate-base eluent, in this analysis the column was operated with a low-conductivity p-hydroxybenzoate-base eluent. This enabled a highly sensitive and baseline separation of seven anions and carbonate ion under a non-suppressor condition.

Sample Preparation

1. 1.Condition a pretreatment cartridge packed with Na⁺ form cation-exchange resin by passing 3 mL of methanol followed by 3 mL of water.
2. 2.Pass 3 mL of sample through the cartridge, discard the first 1 mL, and collect the remaining 2 mL as a sample.

Sample: 100 µL
Anion standard solution

1. 1.F^- 2 mg/L
2. 2.HCO₃^- 20 mg/L
3. 3.Cl^- 3 mg/L
4. 4.NO₂^- 5 mg/L
5. 5.Br^- 10 mg/L
6. 6.NO₃^- 10 mg/L
7. 7.HPO₄^2- 15 mg/L
8. 8.SO₄^2- 15 mg/L

Sample: 100 µL
River water

1. 2.HCO₃^-
2. 3.Cl^-
3. 4.NO₂^-
4. 5.Br^-
5. 6.NO₃^-
6. 7.HPO₄^2-
7. 8.SO₄^2-