Multidimensional chromatography description

The coupling of supercritical fluid extraction (SEE) with gas chromatography (SEE-GC) provides an excellent example of the application of multidimensional chromatography principles to a sample preparation method. In SEE, the analytical matrix is packed into an extraction vessel and a supercritical fluid, usually carbon dioxide, is passed through it. The analyte matrix may be viewed as the stationary phase, while the supercritical fluid can be viewed as the mobile phase. In order to obtain an effective extraction, the solubility of the analyte in the supercritical fluid mobile phase must be considered, along with its affinity to the matrix stationary phase. The effluent from the extraction is then collected and transferred to a gas chromatograph. In his comprehensive text, Taylor provides an excellent description of the principles and applications of SEE (44), while Pawliszyn presents a description of the supercritical fluid as the mobile phase in his development of a kinetic model for the extraction process (45). 

Figure 10.4 Schematic representation of the multidimensional GC-IRMS system developed by Nitz et al. (27) PRl and PR2, pressure regulators SV1-SV4, solenoid valves NV— and NV-I-, needle valves FID1-FID3, flame-ionization detectors. Reprinted from Journal of High Resolution Chromatography, 15, S. Nitz et al, Multidimensional gas cliro-matography-isotope ratio mass specti ometiy, (MDGC-IRMS). Pait A system description and teclinical requirements , pp. 387-391, 1992, with permission from Wiley-VCFI.

Reprinted from Journal of High Resolution Chromatography, 15, S. Nitz et ah, Multidimensional gas chi omatography-isotype ratio mass spectrometry (MDGC-IRMS). Part A system description and technical requirements, pp. 387-391, 1992, with peraiission from Wiley-VCH. 

Fig. 1 Bottom-up and top-down strategies for analyzing proteomic samples. A description of these two processes can be found in Sect. 2. 2-DE two dimensional electrophoresis, n-D-LC multidimensional liquid chromatography, PMF Peptide mass fingerprinting, PTM Post-transla-tional modification, db database. Adapted with permission from Schliiter et al. [21]...

Figure 5 (A) Schematic description of a multidimensional gas chromatography arrangement, where a switching system or valve (V) is located between the two columns. The process of switching the flow between and or to the monitor detector (det M) is not shown. The auxiliary flow (aux) provides flow to the system to assist in the switching process, and/or to provide make-up flow into the column, which Is not receiving flow from the precolumn. is normally a column of regular dimensions, and may incorporate a cryofocusing step at the head of the column. (B) The comprehensive two-dimensional gas chromatography arrangement essentially only requires a mechanism for modulation between the two columns, which provides a series of narrow peaks (at least four normally) to for each D peak. The modulator (M) is shown near the column connection. is normally a short, fast elution column.

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