Nitrogen oxides (NOx), nitrogen monoxide (NO), and tobacco-specific nitrosamines (TSNA) are compounds that are analysed in the mainstream aerosol of heat-not-burn tobacco products, such as IQOS. The purpose of this study was to develop and validate a method able to collect in combination NO/NOx and TSNAs from aerosol and to quantify them precisely and accurately. TSNA results were compared with the reference method, in which aerosol collection is done separately. The mainstream aerosol was collected, using a linear smoking machine under the Health Canada Intensive regimen, in bags for NO/NOx measurement after passing through a glass fibre Cambridge filter pad for TSNA analysis by liquid chromatography coupled with tandem mass spectrometry. The NOx in the bags were quantified by EcoPhysics CLD811 detector, and the results were converted to [µg/item] using an equation derived from the ideal gas law. By combining the aerosol generation, TSNA results showed relative mean differences of -0.52 to 1.26 % compared with the reference method, which is within the variability of the analytical method. For both NO and NOx, the obtained lower limits of quantification were below the lower working range limit (1 ppm), and instrumental repeatability was between 0.18 and 0.42 %. For NO, the r and IP limits were at 0.84 and 1.19 µg/item, respectively, at nominal content (12.6 µg/item), and for NOx, the r limit and the IP limit were at 0.89 and 1.02 µg/item, respectively, at nominal content (12.9 µg/item). Based on these results, the validation of the NO/NOx measurement has been successful. The method was shown to be precise and accurate over the ranges of concentration from 1 to 40 ppm (~0.87 to 35 µg/item) for NO/NOx in mainstream aerosol. In conclusion, it was demonstrated that the combination of aerosol generation does not impact the TSNA results.