Vapor phase detection ofhydrogen peroxide with ambient sampling chemi/chemical ionization mass spectrometry

Abstract

In this paper, we demonstrate a mass spectrometric method for sensitive and rapid detection of gaseous hydrogen peroxide (H₂O₂) using an ambient sampling chemi/chemical ionization source. Metastable helium atoms (He*) were used as the primary ionizing agents and were generated from a dielectric barrier discharge (DBD) source. A gaseous sample of ambient air was drawn into an enclosed ionization chamber and subsequently mixed with metastable species at sub-atmospheric pressure. O₂⁻ ions produced from the ionization of ambient air readily react with H₂O₂ to form the stable [H₂O₂ + O₂]⁻ cluster ion. A detection limit of 0.8 ppbv was achieved by coupling the ion source to a commercial time-of-flight mass spectrometer. The construction of the ion source is simple, and vapors from bulky objects can also be analyzed directly by placing the sample close to the sampling nozzle. The versatility of this ion source for the application in rapid security screening is demonstrated by non-invasive detection of an aqueous solution of hydrogen peroxide concealed in closed beverage bottles.