Detection of Nitric Oxide by Membrane Inlet Mass Spectrometry

: Membrane inlet mass spectrometry (MIMS) is a reproducible and reliable method for the measurement of nitric oxide in aqueous solution with a lower limit of detection of 10 nM and a linear response to 50 μM. MIMS utilizes a semipermeable membrane to partition analytes based on physicochemical properties from the bulk sample into the mass spectrometer. Silastic tubing allows the introduction of small gaseous molecules including nitric oxide (NO) into the high vacuum of a mass spectrometer. We describe the measurement of NO generated chemically from nitrite and MAHMA NONOate as well as enzymatically by nitric oxide synthase (NOS).