Main Speaker: Nicholas H. Snow, Department of Chemistry and Biochemistry, Center for Academic Industry Partnership, Seton Hall University, South Orange, NJ

Title: Six Dimensions of Separations: Are we holding ourselves back with packed column thinking?

Abstract: The advent of readily available high-resolution and sensitivity multidimensional separation and detection techniques such as GCxGC-ToFMS and GC-MS-MS has provided chromatographers with unprecedented separation and detection capability. When combined with on-line sample preparation techniques such as SPME and static headspace extraction, there are now numerous avenues for chromatographers to improve separation selectivity and ultimately resolution. These additional dimensions also provide opportunities to compromise selectivity, especially when combined with historical lessons originally applied to packed columns. Considered holistically, an SPME-GCxGC-ToFMS method actually has up to six dimensions of separation: sampling, extraction, injection, two dimensions of GC and MS detection. Each can generate both desired and undesired selectivity that impacts the ultimate resolution and sensitivity generated by the full method. Using examples from forensic, pharmaceutical and organic contaminant analysis, each of the multiple dimensions of analyses involving SPME, GCxGC-MS and GC-MS-MS will be examined in terms of selectivity (both desired and undesired) selectivity generation and whether they still suffer from packed column thinking. For example, in environmental analysis, it will be shown that, if desired selectivity is maximized and undesired selectivity minimized, the sensitivity of SPME-GC-MS-MS is easily competitive with LC-MS-MS for the analysis of emerging contaminants in water. In pharmaceutical analysis, the six “non-volatile” compounds not included in the standard USP and ICH headspace methods can, in fact, be determined by headspace extraction.  To maximize the potential of GC, all of the six dimensions must be understood and optimized.

Graduate Student Speaker: Mr. Reza Nemati - University of Connecticut

Title: Chromatographic and Mass Spectrometric Methods for Targeted Analysis of a Bacterial Lipodipeptide in Human Samples

Abstract: Human microbiome can be helpful to the host by preventing invasion of pathogens and shaping the immune response of the host. However, microbiome may be harmful in causing acute or chronic disease within the host. Bacteria produce conserved molecules that are unique to microbial metabolism and can be recognized by the host innate immune system through pathogen recognition receptors such as toll-like receptors. We recently identified a unique lipodipeptide, Lipid 654, which is produced by commensal gastrointestinal and oral bacteria. 

Lipid 654 functions as a human and mouse toll-like receptor 2 ligand. To better understand the relationship between Lipid 654 and development of human systemic autoimmunity or other chronic inflammatory diseases, we developed chromatographic and mass spectrometric methods to separate, characterize and quantify preparations of bacteria-derived lipids from tissue and serum or from cultured bacteria. Because Lipid 654 is recovered from common oral bacteroidetes in at least two forms of stereoisomers, it is important to separate these isomers in order to further investigations of the metabolism and biological activity of Lipid 654. The Lipid 654 isomers are indistinguishable by conventional LC-MS. We will discuss two methods of separation of these stereoisomers; one uses differential mobility separation MS and the other uses chiral LC-MS.