δ13C and δD of volatile organic compounds in an alumina industry stack emission

Compound specific isotope analysis (CSIA) is becoming more widely accepted as a tool for determining the sources of contaminants and monitoring their transport and fate in the environment. However, measuring δD of volatile organic compounds (VOCs) in atmospheric samples is still underexplored. The present study applies thermal desorption–gas chromatography–isotope ratio mass spectrometry (TD–GC–irMS) for the first time to measure stable hydrogen isotope analyses of VOCs in an alumina refinery emission. δ13C data is also collected. A sampling train was designed using TenaxTA as the adsorbent material to gain reliable and reproducible results for CSIA. δ13C values for VOCs (C6–C14) ranged from −22 to −31‰, which is similar to δ13C value range reported for naturally occurring components. The δD values (21 to −137‰) in this study were consistently more enriched in D compared to δD values of VOCs previously reported making the δ values of VOCs in the industrial stack unique. Therefore δD analysis may provide a means for tracking VOCs in atmospheric samples.

► VOC in alumina refinery emission analysed by TD–GC–irMS (δ13C and δD).
► δ13C values of VOCs (C6–C14) similar to naturally occurring components.
► Unique δD values of VOCs. Consistently heavier compared to other reported δD values.
► Designed sampling train gains reliable and reproducible results.