Novel Method to\nQuantify Trace Amounts of Isoprene\nand Monoterpene Secondary Organic Aerosol-Markers in Antarctic Ice

Biogenic volatile organic compounds (BVOCs) contribute\nto the formation\nof secondary organic aerosol (SOA) through atmospheric oxidation.\nPreviously detected SOA-markers in northern hemisphere ice cores from\nAlaska, Greenland, Russia, and Switzerland indicate the transportation\nof isoprene and monoterpene oxidation products from their forestry\nsources to these glacial regions. Antarctica is geographically further\nremoved from the BVOC’s source, indicating significantly lower\nSOA-marker concentrations are likely in southern hemisphere ice cores.\nThe aim of this study was to develop a sensitive mass-spectrometric\nmethod to detect and quantify low-abundance SOA-markers of isoprene\nand monoterpenes in ice core samples. Employment of a triple quadrupole\nHPLC–MS method enabled limit of detections in the range of\n0.4–10 ppt for nine terrestrial SOA-markers and a marker of\nbiomass burning, levoglucosan. Quantification was conducted in the\nmultiple reaction monitoring mode with two specific transitions monitored\nfor each target compound. Application of the developed method onto\na section of a Jurassic ice core from Antarctica revealed the presence\nof seven of the target compounds: 2-methylerythritol, 2-methylglyceric\nacid, <i>cis</i>-pinonic acid, 3-methyl-1,2,3-butanetricarboxylic\nacid, pinolic acid, <i>cis</i>-norpinonic acid, and pinic\nacid. Repeatability ranged between 2.2% and 6.2%. This is the first\ntime that such SOA-markers have been discovered and quantified in\nAntarctic ice.