ISO 1138:2007 specifies three methods for the determination of the total sulfur in all types of carbon black for use in the rubber industry:
Method A, using an oxygen bomb calorimeter;
Method B, using a combustion furnace;
Method C, using an automatic analyser.
With respect to safety aspects and test precision, it is preferable to use automatic systems. Classical chemical analysis (Method A and Method B) is acceptable if automatic equipment is not available.