Oxalic acid was analyzed using RSpak KC-811, a column for organic acid analysis. Oxalic acid, a dicarboxylic acid, is not retained on the column under standard eluent conditions (several mM perchloric acid solution) due to ion exclusion effects. It elutes in the same position as inorganic anions such as chloride ions, and thus prevents a quantitative analysis of oxalic acid. In such cases, increase of perchloric acid solution concentration suppresses the oxalic acid dissociation and let it retained in the column.  In this application, use of 50-mM aqueous perchloric acid solution enhanced the retention of oxalic acid and enabled its quantitative analysis without the influence of inorganic anions.

Sample:

1. 1.Anionic Compounds (Cl^-)   10.Succinic acid
2. 2.Oxalic acid                           11.Lactic acid
3. 3.Citric acid                            12.Fumaric acid
4. 4.Tartaric acid                        13.Acetic acid
5. 5.Phosphoric acid                  14.Pyroglutamic acid
6. 6.Malic acid
7. 7.α-Ketoglutaric acid
8. 8.Malonic acid
9. 9.Pyruvic acid
10.