Simultaneous NO and CO(2) measurement in human breath with a single IV-VI mid-infrared laser.

A tunable diode laser absorption spectroscopy (TDLAS) system equipped with a IV–VI mid-IR laser operating near 5.2 µm was used to measure exhaled nitric oxide (eNO) and carbon dioxide CO2 simultaneously in human breath over a single exhalation. Breath was sampled in real time, and eNO levels were measured from seven volunteers, two steroid-naive asthmatics and five nonasthmatics. Measured CO2 levels were used as an internal standard to verify correct breath collection and calculate eNO values. Calculated eNO concentrations agreed well with reported values for asthmatic and nonasthmatic individuals.