In the course of USP column equivalency tests, the Metrosep A Supp 3 - 250/4.0 is applied for the assay of citric acid/citrate and phosphate according to USP general Chapter <345>. This report shows that the Metrosep A Supp 3 - 250/4.0 column is equivalent to packing L61 required in USP general Chapter <345>.