ISSN:
1040-7685
Keywords:
Phase behavior
;
supercritical fluid chromatography
;
supercritical fluid extraction
;
modifier
;
propylene carbonate
;
critical parameters
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The phase behavior (P-T-x) of propylene carbonate was studied using a variable volume view cell for the regions applicable to supercritical fluid chromatography (SFC) and extraction (SFE). Type 5 phase behavior was observed. Phase separation was shown to significantly alter retention and selectivity in the analysis of coal extracts by capillary SFC. Propylene carbonate was found to have limited use as a modifier in capillary SFC. With 5.1 mol% propylene carbonate at 60°C, a single phase is maintained only at pressures above 250 atm.Twenty-two methods used to estimate critical pressure (Pc), twenty-seven methods used to estimate critical temperature (Tc), and thirty methods used to estimate critical volume (Vc) were evaluated for various modifiers employed in supercritical fluid chromatography (SFC). None of the methods could predict Pc, Tc, or Vc to within a 5% relative error for all of the modifiers tested. However, several of the methods were successful in predicting Pc, Tc, or Vc to within 5% for select chemical classes of compounds.Four methods used to estimate the vapor-liquid critical loci of binary mixtures not only failed to accurately predict vapor-liquid separation, but failed to predict the type of phase separation occurring. None of the above methods could reliably estimate the critrical parameters of propylene carbonate or the critical parameters of the mixture.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mcs.1220030410
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