| The accuracy of liquid-liquid phase transition temperatures determined from semiautomated light scattering measurements. | |
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MedLine Citation:
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PMID: 20726651 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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The synthetic-method determination of liquid-liquid coexistence curves using semiautomated light scattering instrumentation and stirred samples is based on identifying the coexistence curve transition temperatures (T(cx)) from sudden changes in turbidity associated with droplet formation. Here we use a thorough set of such measurements to evaluate the accuracy of several different analysis methods reported in the literature for assigning T(cx). More than 20 samples each of weakly opalescent isobutyric acid+water and strongly opalescent aniline+hexane were tested with our instrumentation. Transmitted light and scattering intensities at 2 degrees , 24 degrees , and 90 degrees were collected simultaneously as a function of temperature for each stirred sample, and the data were compared with visual observations and light scattering theory. We find that assigning T(cx) to the onset of decreased transmitted light or increased 2 degrees scattering has a potential accuracy of 0.01 K or better for many samples. However, the turbidity due to critical opalescence obscures the identification of T(cx) from the light scattering data of near-critical stirred samples, and no simple rule of interpretation can be applied regardless of collection geometry. At best, when 90 degrees scattering is collected along with transmitted or 2 degrees data, the accuracy of T(cx) is limited to 0.05 K for near-critical samples. Visual determination of T(cx) remains the more accurate approach in this case. |
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Authors:
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Kevin M Dean; Christopher B Babayco; Daniel R B Sluss; J Charles Williamson |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of chemical physics Volume: 133 ISSN: 1089-7690 ISO Abbreviation: J Chem Phys Publication Date: 2010 Aug |
Date Detail:
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Created Date: 2010-08-23 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375360 Medline TA: J Chem Phys Country: United States |
Other Details:
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Languages: eng Pagination: 074506 Citation Subset: - |
Affiliation:
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Department of Chemistry, Willamette University, 900 State Street, Salem, Oregon 97301, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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