This International Standard specifies a reduced molybdosilicate spectrometric method for the determination of the total silicon content of leather. It is not possible to define the chemical identity of the silicon compounds present in leather and the results are expressed in terms of the oxide SiO2. Organo-silanes are present in leather and they may be determined by this procedure. Organo-silanes are almost quantitatively extracted from leather by tetrahydrofuran or dichloromethane, and this forms the basis of a method for their determination (Elliott, JSLTC, 1964, 48, 105; SLTC-Method SLC/16). A more reliable estimate of inorganic silicon-containing compounds will therefore be obtained if leathers suspected of containing organo-silanes are first extracted with dichloromethan