Portable calibrator for NO based on the photolysis of N ₂O and a combined NO ₂∕NO∕O ₃ source for field calibrations of air pollution monitors

A highly portable calibration source of nitric oxide (NO) based on the photolysis of nitrous oxide (inline-formulaN₂O) supplied by 8 or 16 g disposable cartridges is demonstrated to serve as an accurate and reliable transfer standard for the calibration of NO monitors in the field. The instrument provides output mixing ratios in the range 0–1000 ppb with a precision and accuracy better than the greater of 3 ppb or 3 % of the target NO mixing ratio over a wide range of environmental conditions of ambient temperature (8.5–35.0 inline-formula^∘C), pressure (745–1015 mbar corresponding to 2.7–0.0 km of elevation), and relative humidity (0 %–100 % RH). The combination of the NO calibration source with a previously described ozone calibration source based on the photolysis of oxygen in air provides a new instrument capable of outputting calibrated mixing ratios of NO, ozone (inline-formulaO₃), and nitrogen dioxide (inline-formulaNO₂), where the inline-formulaNO₂ is produced by the stoichiometric gas-phase reaction of NO with inline-formulaO₃. The portable inline-formula $M9inlinescrollmathmlchem{\mathrm{normal\; NO}}_{\mathrm{normal\; 2}}/\mathrm{normal\; NO}/{\mathrm{normal\; O}}_{\mathrm{normal\; 3}}$ 65pt14ptsvg-formulamathimg1de30a4787f90cc6b8f7a18095c3f554 amt-13-1001-2020-ie00003.svg65pt14ptamt-13-1001-2020-ie00003.png calibration source requires no external gas cylinders and can be used for calibrations of NO, inline-formulaNO₂, and inline-formulaO₃ instruments for mixing ratios up to 1000, 500, and 1000 ppb, respectively. This portable calibrator may serve as a convenient transfer standard for field calibrations of ozone and inline-formulaNO_x air pollution monitors.