Determination of NO _x in Mainstream Cigarette Smoke, CORESTA Collaborative Study and Recommended Method

SUMMARY A collaborative study among twelve laboratories was conducted to establish a recommended method for determination of oxides of nitrogen (NOx) in mainstream cigarette smoke. Three cigarette samples, with ISO 3308 total particulate matter yields ranging from 2–17 mg/cig, were evaluated under both a non-intense (ISO 3308) and an intense (ISO 20778) smoking regime to assess the method’s applicability across a range of conditions. Mainstream cigarette smoke was either passed through an in-line detector or collected in a gas-tight system for offline determination of NO x by chemiluminescence. Optional use of glass fiber filter pads enabled gravimetric determination of total particulate matter. Statistical analyses were performed according to ISO 5725 to determine repeatability ( r ) and reproducibility ( R ), and z -scores. Reproducibility, expressed as a percentage of mean yield across all products, smoking regimes, and analysis types, ranged from 15.1–49.7%. NO x yields ranged from 71–437 μg/cig and followed expected trends with respect to total particulate matter and smoking intensity. These results demonstrate the robustness of the proposed method and support its adoption as CORESTA Recommended Method CRM N° 104. [Contrib. Tob. Nicotine Res. 34 (2025) 222–229]