Assay (acidimetric, calc. on anhydrous substance): 99.5 – 100.5 %
Identity (IR-spectrum): passes test
Appearance: white to almost white or colorless crystals
Appearance of solution (200 g/l; water): clear (≤ 3 NTU) and not more intense in color than reference solution Y₇, BY₇ or GY₇
In water insoluble matter: ≤ 50 ppm
Chloride (Cl): ≤ 5 ppm
Phosphate (PO₄): ≤ 10 ppm
Sulphate (SO₄): ≤ 20 ppm
Heavy metals (as Pb): ≤ 5 ppm
Al (Aluminium): ≤ 0.2 ppm
As (Arsenic): ≤ 1 ppm
Hg (Mercury): ≤ 1 ppm
Cu (Copper): ≤ 5 ppm
Fe (Iron): ≤ 3 ppm
Fe (Iron, acc. to Reag. Ph  Eur.): suitable to use in the limit test for iron
Pb (Lead): ≤ 0.5 ppm
Oxalates (as C₂H₂O₄): ≤ 50 ppm
Readily carbonisable substance: passes test
Sulfated ash: ≤ 200 ppm
Water (according to Karl Fischer): 7.5 – 8.8 %
Corresponds to ACS, ISO 6353/2, Reag. Ph. Eur.