Rapid colorimetric method for carbadox in animal feeds

The colorimetric method for carbadox in animal feeds was modified to be simpler and faster. Carbadox is extracted with dimethyl-formamide and separated from interferences on an alumina column in the absence of water by controlling the amount of sample extract on the column and the flow rate. The isolated carbadox is eluted into sodium hydroxide and the resultant yellow chromophor is measured spectrophotometrically at 420 nm.