ISO 5985:2002 specifies two procedures for animal feeding stuffs for the determination of the ash which is insoluble in hydrochloric acid.

The applicable procedure depends on the nature of the sample.

Procedure A is applicable to simple organic animal feeding stuffs and to compound feeding stuffs, except those mentioned under procedure B.

Procedure B is applicable to minerals, mineral mixtures and compound feeding stuffs of which the ash insoluble in hydrochloric acid exceeds 1 % (mass fraction), as determined by procedure A.