Leco

The "COMPARE" feature, available in the Data Processing Method of ChromaTOF , is a single point calibration curve generated from a "Reference" sample, used to compare the Reference sample against a target sample. In this application note, the COMPARE feature will be used to compare two different samples of beer analyzed by SBSEGCxGC- TOFMS. The objective is to identify variations in twenty targeted compounds between the two samples. The Reference sample is of beer stored cold. The other sample is of the same beer that had been stored at an elevated temperature. For the remainder of this work, the sample from which the reference standard is made will be referred to as the "Reference" and the sample being compared to the reference standard will be called the "Sample".

Hops, Humulus lupulus, are one of the primary ingredients in beer and serve as both a natural preservative and as a flavoring agent. These leafy green flowers, shown in Figure 1, are responsible for the characteristic bitterness in beer, but can also impart other flavors such as floral, tangy, piney, or citrusy notes. One factor that impacts the eventual flavor profile of beer is the selection of hop variety, as different strains lead to different flavors and aromas. Another important aspect is the timing of the hop addition during beer brewing. Brewing is a multi-step process that begins by mixing grains with hot water to convert starches in the grain to a sugary solution called wort. The wort is filtered and then boiled together with hops and other specialty ingredients to further develop flavors. At the completion of the boil, yeast is added to initiate fermentation. Hops can be added at any point during or after the boil to bring out desired flavors. Generally, hops are added earlier to draw out bitterness and later to highlight aroma and flavor.

Metabolomics and its toolset provide a foundation for quantitative biology and are indispensible for the detection of small molecules produced and/or transformed in the cells of living organisms.1,2 Different estimates indicate that a majority of differentially expressed analytes remain unknowns. The high sensitivity, peak capacity and reproducibility of GC-MS have made it one of the most widely used techniques for plant and animal metabolite profiling. Time-of-flight mass spectrometry (TOFMS) provides additional benefits such as reduced analysis times, effective peak deconvolution and an ability to interrogate rich data sets repeatedly for novel materials.

Liver disease affects more than 800 million people worldwide causing at least 1.5 million deaths annually. Alcohol consumption and alcoholic liver disease (ALD) continue to be a major cause of morbidity and mortality in the US. Polychlorinated biphenyls (PCBs) are persistent environmental pollutants. Exposures to PCBs have been associated with non-alcoholic fatty liver disease. Monitoring these and other diseases of the liver can be achieved by evaluating metabolites in serum or plasma but a key, basal understanding can come from evaluation of the diseased tissues themselves. Changes detected here will help understand the biology and physiology and may translate to the circulation. Mice provide a good model for this type of research.

The continuous influx of new synthetic drugs such as cannabis analogs into society is a major problem for law enforcement, forensic laboratories, and the medical community.1,2 Relatively simple organic transformations produce novel and licit psychotics that can elude detection by standard analytical methods.3,4 Detection and characterization of synthetic drugs is complicated by 1) the wide range of active ingredients and variety of botanical matrices, 2) the rate at which new drugs and blends appear on the market, 3) the fact that these synthetic drugs and metabolites are often not targeted during routine forensic analyses,5,6 and 4) these newly emerging compounds are typically not present in commercially available mass spectral libraries. High performance time-of-flight mass spectrometry is a practical choice for the analysis of these moving targets.