Getting to the 'Core' of Environmental Change: Analytical Advances for the Analysis and Characterization of Dissolved Organic Matter in Ice Cores Using High Resolution FTICR-MS

As the importance of understanding contemporary environmental issues heightens, many researchers look to the science of ice cores to provide information surrounding past climatic and environmental events extending over hundreds of thousands of years of Earth’s history. Atmospheric composition and temperature data as well as the identification of individual elements and lower molecular weight compounds deposited on the ice surface are examples of the valuable information already obtained from the analysis of ice cores. However the characterization of larger, more complex molecular species, such as dissolved organic matter (DOM), has yet to be performed. The analysis of DOM in ice cores holds much potential and can provide additional evidence regarding past atmospheric and environmental conditions. For example the presence of anthropogenic compounds can provide an understanding of the effects of industrial development just as remnants of biological species may be indicative of glacial and interglacial periods. However studies of this nature are challenging due to the low concentrations of organic material and the need to consume minimal amounts of such a limited sample. In this study, high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is utilized to analyze the low concentration of DOM in ice cores from Antarctica and Greenland. Considering this analytical technique has not been extensively utilized in past studies of ice cores, method development is the most crucial portion of this research. Various minimally invasive sample concentration and/or desalination techniques (including solid phase C18 extraction, PPL extraction, separation using RP-HPLC, and rotovapory concentration) have allowed us to greatly reduce the volume of sample required for analysis. In addition, various ionization sources are being explored (including positive and negative ESI, nanospray ESI, and APPI) to determine the analytical method capable of producing the most informative mass spectra. Once this is accomplished, a comparative analysis can be conducted relating the composition of DOM in ice core samples geographically (within and between either polar region) and chronologically (depth profile of a single region) providing unique and valuable information in an effort to construct a ‘picture’ of past environments on Earth.