2.PrincipleU.K.
2.1.Procedure AU.K.
The sample is extracted with light petroleum. The solvent is distilled off and the residue dried and weighed.
2.2.Procedure BU.K.
The sample is treated under heating with hydrochloric acid. The mixture is cooled and filtered. The residue is washed and dried and submitted to the determination according to Procedure A.