. 2015 Mar 13;5:9096. doi: 10.1038/srep09096

Table 1. ¹⁵NO,¹⁴NO signals (arbitrary sensor signal units) and their isotopic ratio measured in urine, blood and breath samples collected before and after ¹⁵N-arginine injection (standard deviations for n measured samples are given for each value indicating significantly smaller distribution of isotopic ratios as compared to individual concentrations of measured isotopes). *Note: Concentrations of exhaled nitric oxide from the lower airways in healthy patients typically vary from 5 to 20 ppbv³⁸, which contains ~0.07 ppbv ¹⁵NO. To reach such sensitivity the DM-FRS sensor needs ~53 s averaging time, which even at the lowest available gas flow rate setting was too long compared to the time required to flow the 10 mL breath samples provided for this study. Therefore it was not possible to measure the¹⁵NO content in breath samples before the L-[¹⁵N]2-arginine injection.