Fast, high peak capacity separations in comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

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• 作者：Brian D. Fitz ; Ryan B. Wilson ; Brendon A. Parsons ; Jamin C. Hoggard ; Robert E. Synovec ; ^{synovec@chem.washington.edu}
• 关键词：Peak capacity production ; Gas chromatography ; Comprehensive separations ; High throughput
• 刊名：Journal of Chromatography A
• 出版年：2012
• 出版时间：30 November, 2012
• 年：2012
• 卷：1266
• 期：Complete
• 页码：116-123
• 全文大小：1110 K

文摘

Peak capacity production is substantially improved for two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC ¡Á GC-TOFMS) and applied to the fast separation of a 28 component liquid test mixture, and two complex vapor samples (a 65 component volatile organic compound test mixture, and the headspace of warm ground coffee beans). A high peak capacity is achieved in a short separation time by selecting appropriate experimental conditions based on theoretical modeling of on-column band broadening, and by reducing the off-column band broadening by applying a narrow, concentrated injection pulse onto the primary column using high-speed cryo-focusing injection (HSCFI), referred to as thermal injection. A long, relatively narrow open tubular capillary column (20 m, 100 ¦Ìm inner diameter (i.d.) with a 0.4 ¦Ìm film thickness to benefit column capacity) was used as the primary column. The initial flow rate was 2 ml/min (60 cm/s average linear flow velocity) which is slightly below the optimal average linear gas velocity of 83 cm/s, due to the flow rate constraint of the TOFMS vacuum system. The oven temperature programming rate was 30 ¡ãC/min. The secondary column (1.8 m, 100 ¦Ìm i.d. with a 0.1 ¦Ìm film thickness) provided a relatively high peak capacity separation, concurrent with a significantly shorter modulation period, P_M, than commonly applied with the commercial instrument. With this GC ¡Á GC-TOFMS instrumental platform, compounds in the 28 component liquid test mixture provided a ¡«7 min separation (with a ¡«6.5 min separation time window), producing average peak widths of ¡«600 ms full width half maximum (FWHM), resulting in a peak capacity on the primary column of ¡«400 peaks (at unit resolution). Using a secondary column with a 500 ms P_M, average peak widths of ¡«20 ms FWHM were achieved, thus providing a peak capacity of 15 peaks on the second dimension. Overall, an ideal orthogonal GC ¡Á GC peak capacity of ¡«6000 peaks (at unit resolution) was achieved (or a ¦Â-corrected orthogonal peak capacity of ¡«4400, at an average modulation ratio, M_R, of ¡«2). This corresponds to an ideal orthogonal peak capacity production of ¡«1000 peaks/min (or ¡«700 peaks/min, ¦Â-corrected). For comparison, standard split/split-less injection techniques with a 1:100 split, when combined with standard GC ¡Á GC conditions typically provide a peak capacity production of ¡«100 peaks/min, hence the instrumental platform we report provides a ¡«7-fold to 10-fold improvement.