Membrane mass spectrometer inlet for quantitation of nitric oxide

✍ Scribed by Randy S. Lewis; William M. Deen; Steven R. Tannenbaum; John S. Wishnok

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 718 KB
• Volume: 22
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/bms.1200220106

✦ Synopsis

Nitric oxide (NO) is an important physiological and biochemical messenger that may be involved in endogenous carcinogenesis and cell toxicity via formation of N-nitroso compounds or direct DNA damage by nitrosating agents arising from the reaction of NO with 0,. To study the reaction of NO with 0, in model systems and the formation and disappearance of NO in more physiological systems such as cell cultures, we adapted and optimized a membrane mass spectrometer inlet specifically for such analyses. The inlet consisted of Silastic tubing inserted into a Swagelok 'tee', which was attached to the mass spectrometer via the tuning probe. Kinetics of NO disap pearance can be followed under electron impact conditions until NO, interferes via the formation of NO+ during fragmentation of NO,+. The aqueous NO concentration for minimum detection was determined to be 1.4 pM. The inlet response time to step changes in aqueous NO concentrations was 7.0 s, fast enough to permit real-time measurements of aqueous NO changes upon addition of 0,. Finally, the depletion of aqueous NO was observed in the presence of 0,. The relative steady state responses of inlets designed for gas or aqueous samples, and their relative response times, are explained by an analysis based on mass transfer theory.