title: An equation to calculate the actual methylene middle parameter as a function of temperature.
abstract: Methylene middle parameter [Formula: see text] , the product of the methylene group's cross-sectional area ( [Formula: see text] ) and the root square of its dispersive free energy ( [Formula: see text] ), is the key parameter to calculate the dispersive surface components of solids (γs(d)) using inverse gas chromatography (IGC) at different temperatures. The only method reported to calculate [Formula: see text] as a function of temperature is the Dorris-Gray method. However, the conventional values of [Formula: see text] calculated by the Dorris-Gray method depend heavily on theoretical aspects. This paper establishes a novel equation calculating the actual [Formula: see text] as a function of temperature using the latest and most accurate surface parameters of seven successive n-alkanes. The obtained actual [Formula: see text] values are slightly higher those of the conventional [Formula: see text] . At 20°C, the actual [Formula: see text] generates γs(d) values less than those generated using the conventional [Formula: see text] by ∼3%, and this reduction in calculated γs(d) values increases linearly to become ∼5% at 100°C. Therefore, using the new actual [Formula: see text] seems to mitigate the discrepancy between the γs(d) values measured by IGC and those measured by the contact angle method.
authors.affiliation: Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK; Faculty of Pharmacy, University of Damascus, Damascus, Syria. Electronic address: mam71@bath.ac.uk.
authors.forename: Mohammad Amin
authors.initials: MA
authors.lastname: Mohammad
mesh_terms: D000465:Algorithms; D000473:Alkanes / Q000737:chemistry*; D002849:Chromatography, Gas; D013696:Temperature
chemical_list: D000473:Alkanes
keywords: Adhesion retention factor; Chromatographic adhesion law; Inverse gas chromatography; Methylene middle parameter; Surface energy; Surface parameters of methylene