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Soft Mass Spectrometry in Drinking Water Analysis Using Differential Ion Mobility Spectroscopy

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Title: Soft Mass Spectrometry in Drinking Water Analysis Using Differential Ion Mobility Spectroscopy
Author: Lyczko, Jadwiga
Department: Department of Chemistry
Program: Chemistry
Advisor: Gabryelski, Wojciech
Abstract: The analysis of labile ions that easily decompose at various stages of the analytical process is a significant challenge for any analytical method. In this thesis, a new analytical approach based on “soft” mass spectrometry and differential ion mobility was developed that enables the detection of such labile analytes in a quick and convenient fashion, without the need for extensive sample preparation and column separation. Soft mass spectrometry approach combines techniques of electrospray ionization (ESI), differential ion mobility spectroscopy (FAIMS) and mass/tandem mass spectrometry (QTOF-MS/MS). The key feature of ESI-FAIMS-QTOF-MS is the replacement of liquid chromatography by a FAIMS separation technique which eliminates chemical background during the analysis. It also improves the quality of spectral data and provides the detection of thousands of analytes down to a part-per-trillion concentration level. Most importantly, the technique offers extremely soft conditions for ion introduction and their transport through the mass spectrometer. The greatest advantage, in using the soft mass spectrometry approach is that fragile species which were beyond the scope of conventional mass spectrometry approaches can now be analyzed. This thesis demonstrates unique capabilities of the soft ESI-FAIMS-QTOF-MS technique in non-target analysis, which led to the discovery of sulphur-containing polar congeners of thiotetronic acids (TA) in drinking water from underground sources in Canada, United States and Europe. Polar TAs accumulate in underground aquifers and appear to be the most abundant class of organic compounds in groundwater but cannot be detected by conventional mass spectrometry methods due to their extremely fragile nature. Structural elucidation of TAs detected in this study was accomplished using de novo identification approach in which the elemental composition from accurate mass measurements and the manual interpretation of MS/MS data were utilized. TA derivatives were originally isolated from soil bacteria and are investigated in the pharmaceutical industry for their potent activity against a broad spectrum of pathogenic bacteria and negligible toxicity to mammals. We suspect, TA congeners characterized in this study are natural disinfection agents protecting groundwater from bacterial contamination and have minimal biological impact on humans.
Date: 2016-07
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