Progressive extraction profile

Gas is produced to surface separators which are used to extract the heavier ends of the mixture (typically the components). The dry gas is then compressed and reinjected into the reservoir to maintain the pressure above the dew point. As the recycling progresses the reservoir composition becomes leaner (less heavy components), until eventually it is not economic to separate and compress the dry gas, at which point the reservoir pressure is blown down as for a wet gas reservoir. The sales profile for a recycling scheme consists of early sales of condensate liquids and delayed sale of gas. An alternative method of keeping the reservoir above the dew point but avoiding the deferred gas sales is by water injection. 

The 14C content of SOM decreases with depth in the soil profile (Martin et al., 1990). An estimate of the passive pool could be obtained by measurements of the 14C of SOM in deeper layers (Harrison and Broecker, 1993). Physical fractionation and sequential extraction have also been used, and they have shown progressively lower 14C/12C ratios in decomposing residues. 

Figure 14.10. Principal component analysis of Py-FI mass spectra of (a) cold and (b) hot water extracts from the sequence of organic litter layers Oi-Oe-Oa in a beech stand (Fagus sylvat-ica) obtained before (-pre) and after (-post) aerobic incubation. The arrows indicate changes due to progressive decomposition top-down in the litter profile. Reprinted from Landgraf, D., Leinweber, P, and Makeschin, F. (2006). Cold and hot water extractable organic matter as indicators of litter decomposition in forest soils. Journal of Plant Nutrition and Soil Science 169,76-82, with permission of Wiley-VCH.

Determination of the optimum time for which the SPME sorbent will be in direct contact with the sample is made by constructing an extraction-time profile of each analyte(s) of interest. The sorption and desorption times are greater for semi volatile compounds than for volatile compounds. To prepare the extraction-time profile, samples composed of a pure matrix spiked with the analyte(s) of interest are extracted for progressively longer times. Constant temperature and sample convection must be controlled. Stirring the... 

Star fruit juice also induced seizures when applied to cortical areas, showing that convulsant activity is present in crude star fruit extracts. The present data confirm the excitatory profile of AcTx and star fruit extracts. The progressive and sustained EEG epileptiform activity induced by AcTx is a characteristic of known... 

Concerning the development of "zoapatle" as a contraceptive phytomedicine, limited attempts have been made to systematically demonstrate the presence of the different classes of compounds in the traditional decoction. So far, reports are conclusive only about the presence of kaurenic derivatives, kauradienoic acid, kaurenoic acid and monoginoic acid [45] and the oxepane tomexanthin [39]. Progress in analytical methods allows one today to carry out a complete HPLC profile of an aqueous plant extract. Thus, "zoapatle s" decoction should be analyzed again, using the 40 plus isolated compounds as standards. 

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