This result from an internal INBIFO report dated January 1999 shows results for measuring ammonia in Project MIX [89].

(Error bars are SD.) All three ingredient groups were associated with increased TPM, higher gas phase ammonia for ingredient group 1 and lower levels for ingredient groups 2 and 3 (in a dose-dependent manner), reported as statistically significant [90]. Total ammonia was increased in ingredient groups 1 and 2. Because cigarettes with the additives produced more TPM, normalizing the ammonia produced by TPM lowered (and in most cases reversed) the estimated effects of the ingredients on ammonia production.