Distinguishing animal fats from plant oils in archaeological residues is not straightforward. Characteristic plant sterols, such as beta-sitosterol, are often missing in archaeological samples and specific biomarkers do not exist for most plant fats. Identification is usually based on a range of characteristics such as fatty acid ratios, all of which indicate that a plant oil may be present, none of which uniquely distinguish plant oils from other fats. Degradation and dissolution during burial alter fatty acid ratios and remove short-chain fatty acids, resulting in degraded plant oils with similar fatty acid profiles to other degraded fats. Compound-specific stable isotope analysis of delta(13)C(18:0) and delta(13)C(16:0), carried out by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), has provided a means of distinguishing fish oils, dairy fats, ruminant and non-ruminant adipose fats, but plant oils are rarely included in these analyses. For modern plant oils where C(18:1) is abundant, delta(13)C(18:1) and delta(13)C(16:0) are usually measured. These results cannot be compared with archaeological data or data from other modern reference fats where delta(13)C(18:0) and delta(13)C(16:0) are measured, as C(18:0) and C(18:1) are formed by different processes resulting in different isotopic values. Eight samples of six modern plant oils were saponified, releasing sufficient C(18:0) to measure the isotopic values, which were plotted against delta(13)C(16:0). The isotopic values for these oils, with one exception, formed a tight cluster between ruminant and non-ruminant animal fats. This result complicates the interpretation of mixed fatty residues in geographical areas where both animal fats and plant oils were in use.

<div> <div> <div> <p>The exploratory profiling and quantitative bioassays of lipids, small metabolites, and peptides have always been challenging tasks. The most popular instrument platform deployed to solve these problems is chromatography coupled with mass spectrometry. However, it requires large amounts of instrument time, intensive labor, and frequent maintenance, and usually produces results with bias. Thus, the pace of exploratory research is one of poor efficacy and low throughput. The work in this dissertation provides two practical tactics to address these problems. The first solution is multiple reaction monitoring profiling (MRM-profiling), a new concept intended to shift the exploratory research from current identification-centered metabolomics and lipidomics to functional group screening by taking advantage of precursor ion scan and product ion scan. It is also demonstrated that MRM-profiling is capable of quantifying the relative amount of lipids within the same subclass. Besides, an application of the whole workflow to investigate the strain-level differences of bacteria is described. The results have zeroed in on several potential lipid biomarkers and corresponding MRM transitions. The second strategy is aimed to increase the throughput of targeted bioassays by conducting induced nanoelectrospray ionization (nESI) in batch mode. A novel prototype instrument named "Dip-and-Go" system is presented. Characterization of its ability to carry out reaction screening and bioassays exhibits the versatility of the system. The distinct electrophoretic cleaning mechanism contributes to the removal of salt during ionization, which assures the accuracy of measurement.</p></div></div></div>

Yes / Distinguishing animal fats from plant oils in archaeological residues is not straightforward. Characteristic plant sterols, such as ¿-sitosterol, are often missing in archaeological samples and specific biomarkers do not exist for most plant fats. Identification is usually based on a range of characteristics such as fatty acid ratios, all of which indicate that a plant oil may be present, none of which uniquely distinguish plant oils from other fats. Degradation and dissolution during burial alter fatty acid ratios and remove short chain fatty acids, resulting in degraded plant oils with similar fatty acid profiles to other degraded fats. Compound specific stable isotope analysis of ¿13C18:0 and ¿13C16:0, carried out by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), has provided a means of distinguishing fish oils, dairy fats, ruminant and non-ruminant adipose fats but plant oils are rarely included in these analyses. For modern plant oils where C18:1 is abundant, ¿13C18:1 and ¿13C16:0 are usually measured. These results cannot be compared with archaeological data or other modern reference fats where ¿13C18:0 and ¿13C16:0 are measured, as C18:0 and C18:1 are formed by different processes resulting in different isotopic values. Eight samples of six modern plant oils were saponified releasing sufficient C18:0 to measure the isotopic values, which were plotted against ¿13C16:0. The isotopic values for these oils, with one exception, formed a tight cluster between ruminant and non-ruminant animal fats. This result complicates the interpretation of mixed fatty residues in geographical areas where both animal fats and plant oils were in use. / AHRC