Discovery and investigation of naturally occurring antibiotics in drinking water from Ontario using differential ion mobility and mass spectrometry
Department of Chemistry
University of Guelph
Thursday, November 20, 2014
Abstract: Drinking water is a complex and still not fully explored mixture of naturally occurring and anthropogenic chemical components. The major gap in our knowledge about the contamination of drinking water is related to highly polar organic compounds which are usually non-extractable, non-volatile and thermally or chemically labile. The analysis of such contaminants by conventional mass spectrometry methods is associated with additional challenges during sample preparation, chromatographic separation and detection. Our research focuses on developing a new analytical strategy to address tangible needs in water analysis of highly polar organic contaminants.
Our new methods in water analysis combine technologies of electrospray ionization (ESI), differential ion mobility spectroscopy (FAIMS) and high-performance mass spectrometry (MS). The key feature of ESI-FAIMS-MS is the replacement of chromatography by a differential ion mobility separation technique (FAIMS) which eliminates interferences from water samples, improves the quality of spectral data and provides the detection of thousands of water pollutants down to a part-per-trillion concentration level in a quick and convenient fashion without pre-concentration, fractionation, chemical derivation, or column separation. Most importantly, the technique offers extremely “soft” conditions for ion introduction into the mass spectrometer. Soft mass spectrometry is critical for the detection and identification of very labile and previously undetectable contaminants which have been beyond the scope of conventional methods in water analysis for the last 40 years.
I will demonstrate several unique analytical capabilities of ESI-FAIMS-MS in water analysis, focusing on our recent discovery and investigation of natural antibiotics in drinking water from our province. The most abundant organic components in Ontario’s groundwater are thiotetronic acids which are produced by soil bacteria and can accumulate in underground aquifers. Thiotetronic acids are also present in bottled spring/artesian water (from a local underground aquifer) which is widely distributed in Canada and US by a major food company. Thiotetronic acids are associated with in vitro antibacterial activity and only several derivatives such as thiotetramycin (human antibiotic) are active in vivo against a broad spectrum of pathogenic bacteria. Thiotetronic acids are expected to protect the quality of groundwater with respect to bacterial contamination and have rather minimal biological impact on humans.