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Ageing of GC Capillary Columns with Polar Stationary Liquid Phase and Retention Index of Hydrocarbons

L. Soják, I. Ostrovský, R. Kubinec, P. Kuráň, and V. G. Berezkin

Institute of Chemistry, Faculty of Natural Sciences, Comenius University, SK-842 15 Bratislava

 

Abstract: The ageing of capiIlary column with 1,2,3-tris(cyanoethoxy)propane stationary phase was studied. The study, related to the loss of the stationary phase by evaporation from the column, was based on the column conditioning in the range of maximum allowable operating temperature of used stationary phase (140°C). The evaluation of the results was based on the changes of benzene retention index and capacity ratio as well as the peak symmetry of chromatographic zones. Benzene retention index significantly decreased with the time of conditioning - 60 index units (i.u.) during 550 h. This effect was explained with the stationary phase evaporation from the front part of conditioned column. Owing to this there is the change in contributions of absorption and adsorption to the retention of separated compounds. The contribution of adsorption is increased for separated n-alkanes, as reference standards for the retention index system, in comparison to that of benzene. The consequence of such effect is the different dependence of benzene retention index on its capacity ratio for fresh and aged columns. This is one of the main reasons of poorer retention index reproducibility of analytes separated on polar stationary phases.

Full paper in Portable Document Format: 492a80.pdf

 

Chemical Papers 49 (2) 80–84 (1995)

Monday, November 30, 2020

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