The IR absorption method is investigated in detail with respect to a routine application in semiconductor industry laboratories. The experimental and analytical procedures necessary for an accurate determination of the residual carbon acceptor (CAs) concentration also in commercial wafers are given. A specific technique to eliminate the interference fringes arising from multiple reflections inside the wafer is presented. At a measurement temperature of 77 K the detection limit for carbon is 6*1013 cm-3 in wafers of 5 mm thickness. The IR method is also applicable to commercial wafers giving a detection limit of about 6*1014 cm-3.