Anion standards were analyzed using IC I-524A, an anion analysis column for non-suppressor method. This figure shows the effect of pH on retention time with a 2.5 mM phthalic acid eluent. Generally, the retention time decreases with the increase of pH. A peak for MoO₄^2- cannot be obtained below pH 5.5, neither a peak for CrO₄^2- below pH 6.0, nor a peak for H₂PO₄^- can be obtained above pH 4.5.

Sample: 20 μL

1. ClO₄^- 50 mg/L
2. SCN^- 50 mg/L
3. I^- 20 mg/L
4. CrO₄^2- 50 mg/L
5. MoO₄^2- 50 mg/L
6. S₂O₃^2- 50 mg/L
7. SO₄^2- 10 mg/L
8. NO₃^- 10 mg/L
9. Br^- 10 mg/L
10. NO₂^- 10 mg/L
11. Cl^- 10 mg/L
12. F^- 10 mg/L
13. H₂PO₄^- 10 mg/L