| Title: | "Fast, high peak capacity separations in comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry" |
| Author(s): | Fitz BD; Wilson RB; Parsons BA; Hoggard JC; Synovec RE; |
| Address: | "Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195-1700, USA" |
| DOI: | 10.1016/j.chroma.2012.09.096 |
| ISSN/ISBN: | 1873-3778 (Electronic) 0021-9673 (Linking) |
| Abstract: | "Peak capacity production is substantially improved for two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-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 mum inner diameter (i.d.) with a 0.4 mum 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 degrees C/min. The secondary column (1.8m, 100 mum i.d. with a 0.1 mum 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 GCxGC-TOFMS instrumental platform, compounds in the 28 component liquid test mixture provided a approximately 7 min separation (with a approximately 6.5 min separation time window), producing average peak widths of approximately 600 ms full width half maximum (FWHM), resulting in a peak capacity on the primary column of approximately 400 peaks (at unit resolution). Using a secondary column with a 500 ms P(M), average peak widths of approximately 20 ms FWHM were achieved, thus providing a peak capacity of 15 peaks on the second dimension. Overall, an ideal orthogonal GCxGC peak capacity of approximately 6000 peaks (at unit resolution) was achieved (or a beta-corrected orthogonal peak capacity of approximately 4400, at an average modulation ratio, M(R), of approximately 2). This corresponds to an ideal orthogonal peak capacity production of approximately 1000 peaks/min (or approximately 700 peaks/min, beta-corrected). For comparison, standard split/split-less injection techniques with a 1:100 split, when combined with standard GCxGC conditions typically provide a peak capacity production of approximately 100 peaks/min, hence the instrumental platform we report provides a approximately 7-fold to 10-fold improvement" |
| Keywords: | "Coffee/chemistry Gas Chromatography-Mass Spectrometry/*instrumentation/*methods High-Throughput Screening Assays/methods Isomerism Models, Chemical Organic Chemicals/chemistry/isolation & purification Seeds/chemistry;" |
| Notes: | "MedlineFitz, Brian D Wilson, Ryan B Parsons, Brendon A Hoggard, Jamin C Synovec, Robert E eng Netherlands 2012/10/23 J Chromatogr A. 2012 Nov 30; 1266:116-23. doi: 10.1016/j.chroma.2012.09.096. Epub 2012 Oct 3" |
