IC SI-35 2B, an anion analysis column was used to analyze perchlorate and its related anions. LC/MS analysis of perchlorate ions has gained attention in recent years, which includes a published EPA Method 6850. Perchlorate ions can be detected at m/z 99 and m/z 101, and their peak area ratio corresponds to the isotopic ratio of ³⁵Cl and ³⁷Cl. Fragment ions of perchlorate ions, m/z 83 and m/z 85 are detected. Their m/z are the same as chlorate ion m/z, but since perchlorate ions and chlorate ions have sufficiently different retention times, this allows their differentiation. Additionally, the m/z 99 ion of perchlorate ions may be influenced by H³⁴SO₄^-, which has the same m/z, but as they also have distinct retention times enabling the differentiation.
After confirming the retention times of each ion using a mixed standard solution (1 μg/mL each), we measured a mixed standard solution containing 50 ng/mL each. Peaks of perchlorate ions were observed at both m/z 99 and m/z 101. The effects of other components on the perchlorate ion peaks can be checked by the peak area ratio of ³⁵ClO₄^- to ³⁷ClO₄^-. In this analysis, even at low concentrations of perchlorate ions, peaks derived from ³⁷ClO₄^- can be determined.

Sample: 5 μL
Mixed standard solution (1 μg/mL each)

1. Perclorate, ClO₄^-
2. Hydrogen sulfate, HSO₄^-
3. Chlorate, ClO₃^-
4. Chloride, Cl^-

Sample: 5 μL
Mixed standard solution (50 ng/mL each)

1. Perclorate, ClO₄^-