Antifoaming agents are commonly added to mammalian cell culture during production of monoclonal antibodies (MAb), since foaming can have a negative impact on MAb production. The foaming can reduce purification process capacity, increase processing time, contribute to batch contamination (due to foam overflow), and reduce cell productivity due to entrainment and shear , . Even though few regulatory guidelines exist in regard to antifoam compounds (mostly for food production) , these compounds can potentially be carried throughout the process, making it necessary to track them during purification to demonstrate clearance. Several challenges exist in detecting Antifoam C due to poor UV absorbance, low solubility in the solvents screened and its presence at very low predicted concentrations in the process streams. This paper will present an effective detection method for Dow Corning Medical Antifoam C using dynamic light scattering (DLS), total solids analysis (TSA), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The clearance of Antifoam C through dead-end and tangential flow filtration processes was characterized using both deionized water and cell culture media spiked with Antifoam C at 10x the process concentration. The parameters investigated were Antifoam C feed concentration, flux, filter loading, trans-membrane pressure, and processing temperature. Experimental Antifoam C clearance data were compared to an estimated clearance based on assumptions concerning the theoretical distribution of antifoam in the process streams. At room temperature (20°C), a reduction of 7.1x was observed for bioburden reduction filtration while reductions ranging from 6.6x to 8.0x were observed for depth-filtration.