AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Negative-ion Electrospray as an Ion Source for Chemical Ionization Mass Spectrometry of Atmospheric Gaseous Inorganic/organic Acids and Clusters
JUN ZHAO, Coty Jen, Modi Chen, Michael J. Lawler, Peter McMurry, James N. Smith, University of Minnesota
Abstract Number: 633 Working Group: Instrumentation and Methods
Abstract Electrospray ionization has been widely employed as an ionization technique in mass spectrometry for chemical analysis of organic compounds, especially biological macromolecules. Another ionization method, ionizing radiation, which provides a stable source of reagent ions, has typically been employed for chemical ionization mass spectrometry of trace atmospheric compounds. Hazards associated with the use of radioactive sources and difficulties with obtaining permits to transport equipment and to operate in the field provide obstacles to this approach. In this work, we present an alternative chemical ionization source that utilizes negative-ion electrospray of acetic acid or nitric acid solutions to produce primary acetate or nitrate cluster ions. A high resolution differential mobility analyzer (HRDMA) coupled to a sensitive electrometer was employed to classify the ions generated from electrospray of the above solutions. A series of inorganic (e.g., sulfuric acid and nitric acid) and organic acids (e.g., formic acid and malonic acid) were tested to investigate the effects of the solvents and multiple charging on the efficiency of chemical ionization. Oxidation products from ozonolysis of monoterpenes in chamber and flowtube experiments were measured with this ionization technique. The advantages and disadvantages of electrospray ion sources will be also discussed.