With temperature gradient column

Figure 7. Supercritical fluid extraction with temperature gradient column. (Reproduced with permission from Ref. 20. Copyright 1986 American Oil Chemists Society.)...

The Py-GC/MS analysis of the browning polymer from glucose and ammonia (from diammonium phosphate) is shown in Figure 11.2.1. The pyrolysis was performed at 600° C for 10 sec. in a filament pyrolyser (CDS 1000), and the separation was done on a Carbowax column 60 m long, 0.32 mm i.d. and 0.25 pm film thickness, with temperature gradient of the GC oven between 40° C and 240° C. 

Pressure Drop low pressure drop is necessary to reduce temperature gradients between top and bottom of the column. High pressure drop is usually (but not always) associated with uneconomical... 

The temperature with large columns may not be homogenous. A mathematical model of the effect of a radial temperature gradient has been developed and validated on octadecyl-packed columns of 11-15 cm diameter... 

SFC-NMR is available from 200 to 800 MHz, and is suitable for all common NMR-detected nuclei. SFC/SFE-NMR requires dedicated probe-heads for high pressure (up to 350 bar) and elevated temperature (up to 100 °C). SFC-NMR is carried out with conventional packed columns, using modifier, pressure and temperature gradients. The resolution of 1H NMR spectra obtained in SFE-NMR and SFC-NMR coupling under continuous-flow conditions approaches that of conventionally recorded NMR spectra. However, due to the supercritical measuring conditions, the 111 spin-lattice relaxation times 7) are doubled. 

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