Selection of liquid phases for glass capillary gas chromatography of monoterpene hydrocarbons.

Glass capillary columns with liquid phases of different polarities were prepared and tested. Of the nine liquid phases used (Apiezon L, SE-30, OV-101, Ucon 50 LB 550X, Emulphor ON-870, Carbowax 20M, FFAP, SP-1000 and Silar 10C) FFAP was the most suitable for the separation of monoterpene hydrocarbons of Scots pine needle oil. For the monoterpene mixtures which contain alpha-thujene and/or tricyclene together with alpha-pinene, only non polar or semipolar columns, such as SE-30, OV-101 or Ucon 50 LB 550X, are to be recommended. Of the polar phases Carbowax 20M and FFAP were found to be the most effective for p-menthadienes. Resolution and relative retention values for some problematic component pairs as well as relative retention times of monoterpene hydrocarbons were calculated. General aspects. the column characteristics, injection technique, effect of temperature on the resolution and artefacts as well as the polarizability of the components as a funktion of the retention have been discussed.