Gas chromatography study of silica modified with polyfluoroalkyl groups.
Silicas with attached polyfluoroalkyl groups were studied by gas chromatography (GC) at zero surface coverage. Organic molecules (n-alkanes, ethers, esters, ketones, etc.) were used as test compounds. The contributions of molecule groups to the Gibbs energy of adsorption deltaGi, and the contributions of specific energy interactions deltaG(sp) as well as Kováts retention indices were calculated. The strong and weak points of the two approaches (deltaGi, deltaG(sp)) were discussed. It was shown on the basis of both approaches that adsorption process on polyfluoroalkyl silicas is to be described by the low contribution of hydrocarbon groups (dispersion interactions) and sufficiently high contribution of groups reinforcing specific interactions. The significant role of entropy in thermodynamic of retention was shown by example of adamantane adsorption.
Gurevich
Kseniya B
KB
Laboratory of Adsorption and Chromatography, Department of Chemistry, Lomonosov State University, Leninskie Gory, 119899 Moscow, Russia. hij629@odintsovo.comcor.ru
Roshchina
Tat'yana M
TM
D002849:Chromatography, Gas / Q000379:methods*; D005461:Fluorine / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*
D005461:Fluorine; D012822:Silicon Dioxide