Oxalic acid is found in various foods, some of which contains around 1% oxalic acid. ODS column is often used as a separation column for analysis of oxalic acid. However, it is difficult to separate oxalic acid from interfering peaks because oxalic acid is highly hydrophilic and poorly retained on ODS columns.
Inertsil Amide, in which porous silica gel having a chemically bonded carbamoyl group is packed, was used in this
note. In contrast to ODS columns, oxalic acid was well retained on Inertsil Amide, and its concentration in pickled ginger was determined.
Porous silica gel having a chemically bonded carbamoyl group is added as a packing material for chromatography in Japanese Phramacopeia 16, which went into effect in April, 2011.