ANALYSIS OB POLAR ORGANIC-COMPOUNDS USING CHARGE-EXCHANGE IONIZATION AND MEMBRANE INTRODUCTION MASS-SPECTROMETRY

Charge exchange ionization in conjunction with membrane introduction m ass spectrometry provides a sensitive method for the detection of pola r volatile organic compounds and semivolatile compounds in air. Sample introduction into an ion trap mass spectrometer was accomplished with a hollow fiber silicone membrane, assembly. Atmospheric oxygen, which diffuses through the membrane, was used as the charge exchange reagen t, Chemical ionization parameters -were optimized using methyl ethyl k etone (2-butanone) standards in air, Several other oxygen-containing c ompounds, including acetone (2-propanone), methyl isobutyl ketone (4-m ethyl-2-pentanone), propanal, isopropyl alcohol (2-propanol), cyclohex anol, dimethyl sulfoxide (sulfinylbismethane), 2-(diethylamino)ethanol , and dimethyl methylphosphonate were analyzed with this technique. Th is method was used to obtain mass spectra for a variety of classes of compounds and produced a 4-20-fold improvement in response for all of the polar compounds we examined when compared to signal obtained from electron ionization.