Determination of carbon black on silver membrane filters from rubber factory dust

The NIOSH criteria document for carbon black cites a method for the determination of carbon black in the workplace atmosphere by membrane filter collection and weighing of the particulates. If particulates other than carbon black are present, they will be determined along with carbon black giving false high measurements for carbon black. All manufactured rubber articles, including tires, contain a wide variety of organic and inorganic additives, which may be present in the workplace atmosphere. These particulates must be separated from carbon black before an accurate determination of the amount of carbon black can be made. The proposed method solves this problem by removing organic additives from a silver membrane filter with organic solvents, heating the filter to 550 degrees C to remove only carbon black and determining the remaining inorganics by a final weighing of the filter. Not only can carbon black be determined by this method but the amount of organic and inorganic additives also can be evaluated.