ABSTRACT
Lipid metabolism is recognised as being central to growth, disease and health. Lipids, therefore, have an important place in current research on globally significant topics such as food security and biodiversity loss. However, answering questions in these important fields of research requires not only identification and measurement of lipids in a wider variety of sample types than ever before, but also hypothesis-driven analysis of the resulting 'big data'. We present a novel pipeline that can collect data from a wide range of biological sample types, taking 1 000 000 lipid measurements per 384 well plate, and analyse the data systemically. We provide evidence of the power of the tool through proof-of-principle studies using edible fish (mackerel, bream, seabass) and colonies of Bombus terrestris. Bee colonies were found to be more like mini-ecosystems and there was evidence for considerable changes in lipid metabolism in bees through key developmental stages. This is the first report of either high throughput LCMS lipidomics or systemic analysis in individuals, colonies and ecosystems. This novel approach provides new opportunities to analyse metabolic systems at different scales at a level of detail not previously feasible, to answer research questions about societally important topics.
ABSTRACT
The use and compatibility of a dual-ionization TOFMS operating an EI source and a CI source in parallel using a single TOF mass analyzer with flow modulated two-dimensional GC (GC×GC) is described. Important figures of merit of the mass spectrometer that are required for two-dimensional GC hyphenation such as acquisition speed, ion source response, EI/CI switching, the GC transfer, and data alignment are carefully investigated and addressed. Improved fast switching ion optics allow switching in a 100 Hz frequency between EI and CI spectra sampled from the same GC×GC effluent. The spectra quality also influenced by the preseparation, especially of the EI source, is compared to a standard setup operating a single quadrupole MS coupled to the same GC system. Further, two setups including and excluding an additional flame ionization detector are presented. High increments in CI sensitivities are achieved by utilizing the high pumping efficiencies of the CI stage of the used mass spectrometer. By leading high flow ratios of the GC×GC modulation flows toward the CI source, the intensity can be increased by factors of up to 37 while maintaining the pressure balance of the less robust EI source. Finally, thermal desorption GC×GC-EI&CI-TOFMS analyses of traffic emission samples from a federal highway in Germany are executed with the presented setup.
ABSTRACT
Comprehensive two-dimensional gas chromatography (GC × GC) is amongst the most powerful separation technologies currently existing. Since its advent in early 1990, it has become an established method which is readily available. However, one of its most challenging aspects, especially in hyphenation with mass spectrometry is the high amount of chemical information it provides for each measurement. The GC × GC community agrees that there, the highest demand for action is found. In response, the number of software packages allowing for in-depth data processing of GC × GC data has risen over the last couple of years. These packages provide sophisticated tools and algorithms allowing for more streamlined data evaluation. However, these tools/algorithms and their respective specific functionalities differ drastically within the available software packages and might result in various levels of findings if not appropriately implemented by the end users. This study focuses on two main objectives. First, to propose a data analysis framework and second to propose an open-source dataset for benchmarking software options and their specificities. Thus, allowing for an unanimous and comprehensive evaluation of GC × GC software. Thereby, the benchmark data includes a set of standard compound measurements and a set of chocolate aroma profiles. On this foundation, eight readily available GC × GC software packages were anonymously investigated for fundamental and advanced functionalities such as retention and detection device derived parameters, revealing differences in the determination of e.g. retention times and mass spectra.