The LMCS performs its function by o

The LMCS performs its function by oscillating back-and-forth along the column, but there are important differences between the Figure 1 and Figure 4 arrangements.

1. The 2D column in GC×GC is relatively short. Contrast this with the long – or more classical length 2D column – in MDGC. One may feel that the short 2D column will not have much separation capacity, but this fails to recognise differences in GC×GC. MDGC has a few discrete heart-cut events. Normally the heart-cuts might be all collected together (in a cryotrap) and then the oven cooled and the 2D column eluted in one run, over the time frame of a conventional GC analysis. It is also possible to put the 2D column in a second oven, and/or to pass the heart-cuts to the 2D column without cryotrapping.
The sampling of 1D peaks is normally done at a rate faster than the elution
time of a 1D peak. We developed the concept of the modulation ratio (MR) to define this process (ref 143).

2. The short 2D column in GC×GC means that the 2D analysis is completed in fast – very fast – time, eg. 2-6 s. This now permits ‘modulations’ of the interface device (LMCS here) to be conducted very rapidly, maybe every 2-6 s. We call this the modulation period, PM. Since the two columns are in direct
fluid connection, all the sample peaks exiting the 1D column enter the 2D
column. And part of the peak that enters the cryotrap is focussed into a sharp

band since (ideally) the cryotrap acts as a collection zone – or as a ‘gate’. The sharp band can then be passed to the 2D column simply by modulating the LMCS. Here, two effects can be noted.
First. If a peak width exceeds the modulation period (1wb > PM), then that
peak entering the modulator will be modulated into more than one peak on the
2D column. We refer to this as the modulation ratio, MR, the peak width of the
1D peak / PM. This is a significant departure from classical GC where normally
each single compound will have a single measured response. In a data system, we now have to have some way to deal with MULTPLE PEAKS from a single compound.
Second. The 2D column should – MUST – have a phase coating that is
different from that of the first. This is the basic tenet of multidimensionality. Since we have two GC columns, one might argue that this cannot constituent a multidimensional system (i.e. two independent techniques do not exist – as in the case of GC-MS). But we can fall back on the idea of polarity of a GC column to discuss multidimensionality further. If two compounds elute at the same time from a first column, can we know which compound will elute first from a second column? If we do not know their ‘polarity’ – which is better
expressed as the different retention mechanism on the 2D column – then we
will not be able to predict their retention. Thus we can now state that multidimensionality exists if the ‘mechanism’ of one dimension is different to that of the other dimension, then we can have independent analysis properties. Just as the mechanism of GC is different to that of MS, then the mechanism of a polar column is different to that of a non-polar column. Of course, we still have ‘boiling point’ as a primary mechanism determining retention in GC

ผลลัพธ์ (อังกฤษ) 2:

The LMCS performs its Function by oscillating back-and-Forth along The Column, but there are important The Differences between Figure 1 and Figure 4 arrangements. 1. The 2D column in GC × GC is relatively short. Contrast this with the long - or more classical length 2D column - in MDGC. One may feel that the short 2D column will not have much separation capacity, but this fails to recognise differences in GC × GC. MDGC has a few discrete heart-cut events. Normally the heart-cuts might be all collected together (in a cryotrap) and then the oven cooled and the 2D column eluted in one run, over the time frame of a conventional GC analysis. It is also possible to Put The 2D Column in A second Oven, and / or to Pass The Heart-Cuts to The 2D Column without Cryotrapping. The Sampling of 1D Peaks is normally done at A rate Faster than The elution. time of A 1D Peak . We developed The Concept of The modulation ratio (MR) to define this Process (Ref 143). 2. The short 2D column in GC × GC means that the 2D analysis is completed in fast - very fast - time, eg. 2-6 s. This now permits 'modulations' of the interface device (LMCS here) to be conducted very rapidly, maybe every 2-6 s. We call this the modulation period, PM. Since The Two Columns are in Direct. Fluid Connection, The Sample Peaks exiting all enter The Column The 1D 2D. Column. The Peak and part of that is focussed Into A sharp Enters The Cryotrap. Band since (Ideally) The Cryotrap ACTS as A Collection Zone - or as A 'Gate'. The sharp band can then be passed to the 2D column simply by modulating the LMCS. Here, Two Effects Can be noted. First. If A Peak width modulation The Period exceeds (1WB> PM), then that. entering Peak Into The modulator Will be modulated more than One on The Peak. 2D Column. We refer to this as The modulation ratio, MR, The width of The Peak. 1D Peak / PM. This is A significant Departure from classical GC Where normally. Each Single Compound Will have A Single Response measured. In A Data System, We now have to have some PEAKS Way to Deal with multple from A Single Compound. Second. The 2D Column should - MUST - have A Phase Coating that is. different from that of The First. This is the basic tenet of multidimensionality. Since we have two GC columns, one might argue that this cannot constituent a multidimensional system (ie two independent techniques do not exist - as in the case of GC-MS). But we can fall back on the idea of polarity of a GC column to discuss multidimensionality further. If two compounds elute at the same time from a first column, can we know which compound will elute first from a second column? If We do Not know their 'Polarity' - which is better. expressed as The Retention different mechanism on The 2D Column - then We. Will Not be Able to predict their Retention. Thus we can now state that multidimensionality exists if the 'mechanism' of one dimension is different to that of the other dimension, then we can have independent analysis properties. Just as the mechanism of GC is different to that of MS, then the mechanism of a polar column is different to that of a non-polar column. Of course, we still have 'boiling point' as a primary mechanism determining retention in GC.