Whether ammonia-forming ingredients added to tobacco and ammonia in smoke affect the ability of the Cambridge filter pad to trap nicotine in the federal trade commission (FTC) method was examined. Three commercial cigarettes, two industry reference cigarettes, and four specially designed test cigarettes were used in this study to represent cigarettes with different construction and mainstream (MS) smoke yield characteristics. One of the commercial cigarettes, a us 1998 Marlboro lights (R) king size cigarette, was used as a control cigarette for the four experimental test cigarettes. The test cigarettes differed from the control cigarette as follows: first, a reduction in ammonia-forming ingredients added to the reconstituted tobaccos; second, no ammonia-forming ingredients added to the reconstituted tobacco; third, no ingredients at all added to the reconstituted tobaccos; and fourth, no ingredients at all added to the entire tobacco blend. An XAD-4 tube was placed downstream of the standard Cambridge filter pad in the FTC method to trap the gas-vapor phase nicotine for subsequent analysis. The Cambridge filter pad used in the FTC method was determined to provide greater than 99% trapping efficiency for MS smoke nicotine from cigarettes with widely different soluble ammonia levels in filler and MS smoke ammonia yields.