1,721,015 research outputs found

    Flow-modulation low-pressure comprehensive two-dimensional gas chromatography

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    The present research is specifically based on the use of greatly-reduced gas flows, in flow-modulator (FM) comprehensive two-dimensional gas chromatography systems. In particular, focus of the present research is directed to FM devices characterized by an accumulation stage, and a much briefer re-injection step. It has been widely accepted that the operation of such FM systems requires high gas flows (≥20. mL/min), to re-inject the gas-phase contents of sample (or accumulation) loops, onto the second column. On the contrary, it will be herein demonstrated that much lower gas flows (≈ 6-8. mL/min) can efficiently perform the modulation step of re-injection. The possibility of using such improved operational conditions is given simply by a fine optimization of the processes of accumulation and re-injection. The application of lower gas flows not only means that second-dimension separations are carried out under better analytical conditions, but, even more importantly, greatly reduces problems which arise when using mass spectrometry (i.e., sensitivity and instrumental pumping capacity)

    Use of greatly-reduced gas flows in flow-modulated comprehensive two-dimensional gas chromatography-mass spectrometry

    No full text
    The present research is specifically based on the use of greatly-reduced gas flows, in flow-modulator (FM) comprehensive two-dimensional gas chromatography systems. In particular, focus of the present research is directed to FM devices characterized by an accumulation stage, and a much briefer re-injection step. It has been widely accepted that the operation of such FM systems requires high gas flows (≥20. mL/min), to re-inject the gas-phase contents of sample (or accumulation) loops, onto the second column. On the contrary, it will be herein demonstrated that much lower gas flows (≈ 6-8. mL/min) can efficiently perform the modulation step of re-injection. The possibility of using such improved operational conditions is given simply by a fine optimization of the processes of accumulation and re-injection. The application of lower gas flows not only means that second-dimension separations are carried out under better analytical conditions, but, even more importantly, greatly reduces problems which arise when using mass spectrometry (i.e., sensitivity and instrumental pumping capacity)

    Potential of Comprehensive Two-Dimensional Gas Chromatography for the Analysis of Lipids

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    The field of lipid analysis is an extremely important area of research in food chemistry; such importance is related to the fundamental biological functions of lipids such as structural components of cell membranes, energy storage compounds, signaling molecules, etc. From a human nutritional viewpoint, oils and fats provide not only energy but also essential fatty acids, polyunsaturated fatty acids (PUFAs), sterols, and vitamins. Additionally, lipids play a crucial role in human health; in fact, a number of disease states are related to an excessive or unbalanced lipid consumptio
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