Carbonates in feed: the official method returns to Regulation 152/2009 a year after its deletion — decomposition with hydrochloric acid (1.10 g/mL), CO₂ volume measured with a Scheibler-Dietrich apparatus or a calcimeter, result as calcium carbonate against 0.5 g of pure CaCO₃; test portion 0.5 g, 1 g or 2–3 g
Commission Implementing Regulation (EU) 2025/782, published on 24 April 2025, adds Part P — determination of carbonates in feed — to Annex III to Regulation (EC) No 152/2009. The same method had been deleted by Implementing Regulation 2024/771, which considered that EU feed law no longer required compliance checks for it. The Commission reinstates it because carbonates have to be quantified in the authorised feed additive lanthanum carbonate octahydrate, and the Catalogue of feed materials (Regulation No 68/2013) requires a compulsory declaration of calcium carbonate for certain feed materials.
- Scope and principle: the method determines carbonates, conventionally expressed as calcium carbonate, in feed — except feed containing iron carbonate. Carbonates are decomposed with hydrochloric acid, the CO₂ released is collected in a graduated tube and its volume is compared with that released under the same conditions by 0.5 g of pure calcium carbonate. Reagents: hydrochloric acid of density 1.10 g/mL, pure calcium carbonate, sulphuric acid approx. 0.05 mol/L coloured with methyl red (the liquid in the apparatus tubes).
- The test portion depends on the carbonate content (as CaCO₃): 0.5 g at 50–100 %, 1 g at 40–50 %, 2–3 g for other products. All determinations are carried out under the same conditions to avoid corrections for differences in temperature and pressure — preferably in a temperature-controlled room. With the Scheibler-Dietrich apparatus and a sample above 2 g, 15 mL of distilled water is first placed in the flask, the same in the control test; with an apparatus of different volume, test portions and calculation must be adapted.
- Calculation: X = V × 100 / (V₁ × 2m), where X — % (w/w) of carbonates as calcium carbonate, V — mL of CO₂ from the sample, V₁ — mL of CO₂ from 0.5 g of CaCO₃, m — sample weight in grams. The appendix describes the procedure step by step: flask with a small tube of unbreakable material holding 10 mL of acid, zeroing with the three-way cock, slow addition of the acid, pressure equalisation with the mobile tube, shaking until CO₂ release stops and reading after a few minutes once the gas volume is constant; control test on 0.5 g of calcium carbonate.
- Background: Implementing Regulation 2024/771 of 29 February 2024 replaced the annexes to Regulation 152/2009 in their entirety and deleted, among others, the methods for volatile nitrogenous bases and carbonates (no compliance-control requirement), replaced the diclazuril method and referred free and total gossypol to EN standards. A year later carbonates return as Part P, after Part O (chlorine from chlorides). Regulation 2025/782 entered into force on the twentieth day after publication.