Coupling a gas chromatograph simultaneously to a flame ionization detector and chemical ionization mass spectrometer for isomer-resolved measurements of particle-phase organic compounds

Abstract. Atmospheric oxidation products of volatile organic compounds consist thousands unique chemicals that have distinctly different physical and chemical properties depending on their detailed structures functional groups. Measurement techniques can achieve molecular characterizations with details down to groups (i.e., isomer-resolved resolution) are consequently necessary provide understandings differences fate transport within isomers produced in the process. We demonstrate a new instrument coupling thermal desorption aerosol gas chromatograph (TAG), which enables separation isomers, high-resolution time-of-flight ionization mass spectrometer (HR-ToF-CIMS), has capability classifying unknown by formulas, flame detector (FID), provides near-universal response compounds. The TAG-CIMS/FID is used measurements samples from liquid standard injections particle-phase organics generated flow reactors. By TAG CIMS, CIMS enhanced an additional dimension information (resolution individual molecules) at cost time resolution one sample per hour instead minute). found prevalent matrix average number three five formula precursors experiments. Additionally, multi-reagent mode investigated both zero air iodide introduced as reagent ions, examine feasibility extending use broader range analytes still selective ions. While this approach reduces iodide-adduct ions factor 2, [M ? H]? + O2]? lower-polarity increase 5 10, improving detection CIMS. method expands detected species using two reagents simultaneously, enabled pre-separation analyte molecules before ionization.