Plots of relative retention against solute boiling point indicate extra solute interactions with a liquid crystal polysiloxane stationary phase

• Published in: Journal of Chromatography A Vol. 743; no. 2; pp. 341 - 346
• Main Author: Betts, T.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 06-09-1996
• Subjects: Boiling point; Liquid crystals; Mesogenic polymeric methyl siloxane; Relative retention; Stationary phases, GC; Stationary phases, GC; Liquid crystals; Relative retention; Mesogenic polymeric methyl siloxane; Boiling point
• ISSN: 0021-9673
• DOI: 10.1016/0021-9673(96)00330-5

Using a commercial liquid crystal polysiloxane phase MPMS capillary, relative retention times to
n-tetradecane were plotted against literature boiling points (°C, 760 nm) for 26 solutes found in volatile oils. Values for five low polarity solutes were used to determine expressions for lines of best fit at 160°C (above MPMS melting point) and 130°C (below it). These expressions predicted values for some acyclic substances. Most solutes gave higher relative retentions at the higher temperature, which is different to conventional and cyclodextrin phases, so confirming a change of MPMS state. However, differences between observed and calculated (using the above expressions) values were nearly the same at both temperatures for twenty solutes, suggesting that MPMS does not always behave as an unmelted phase below its melting point. The remaining two aromatic and three acyclic monoterpenoid solutes showed more retention at the lower temperature, implying some rejection by the melted liquid crystal. Three other lines of best fit were considered for some aromatic substances and for some monoterpenoids.