En l'absence de persulfates (titre A) : on ajoute de l'acide sulfurique dilué à une partie de la solution d'échantillon acide (titre B, point 4.1), ce qui entraîne la formation d'un précipité blanc de sulfate de baryum.
Barium peroxide is identified by the formation of hydrogen peroxide after acidification of the sample (A.4.2), and by the presence of the barium ion: - in the absence of persulphates (A), by adding dilute sulphuric acid to a portion of the acid sample solution (B.4.1), as a result of which a white precipitate of barium sulphate is formed.
