This system is an ‘analytical’ scal

This system is an ‘analytical’ scale preparative GC system, which can target small sections of a sample separated through the 1D column, trap this section in the loop which is isolated in space from prior and subsequent peaks, and then release the peak(s) of interest to a 2D column. Multiple peaks in the target section are then separated. At the end of the 2D column, a Deans switch (DS) can further be used to heart-cut one single peak to a external trapping assembly (xTA). By making repeat injections, it is possible to concentrate the single peaks into sufficient amount to allow spectroscopic techniques such as NMR to be used for characterisation of the peak. This is a powerful addition to classical mass spectrometry methods, to add significant identification capability for chemical structural assignment.

We make wide use of Deans switches and related devices promoted as Capillary Flow Technology by Agilent Technologies (see for example http://www.chem.agilent.com/en-US/Pages/Homepage.aspx; and search Capillary Flow Technology). This is shown as DS in Figure 4.

The above system allows the improved separation of heart-cuts, accomplished by selection of overlapping target zones in the loop which are then passed through the
2D column, to be switched into the DS. Ideally this gives a single compound product
which, when the sample is injected many times, is concentrated up to a mass that allows various spectroscopic methods to be employed. One of these is NMR. The list of publications reports various such applications (see refs 188, 200, 201, 210, 213,
228, 251), which we have used to demonstrate the basic method.