Metallomesogens as stationary phases for the separation of phenols by gas chromatography

Metal complexes of 4-decanoxydithiobenzoate (DDTBA) and 4-(dec-9'-en-1'-oxy )dithiobenzoate siloxane polymer (P-DODTBA) were prepared and used as stati onary phases in ligand-exchange gas chromatography for the separation of ph enols. A better separation of phenols was achieved in the liquid crystallin e state than in the solid state. Van't Hoff plots as a function of temperat ure indicated that phase transitions were occurring. From specific retentio n volumes measured at various temperatures in each of the DDTBA-Zn and DDTB A-Ni fluid phases, the thermodynamic behavior of phenols is discussed. The DDTBA-Zn phase showed a higher solute-solvent interaction than DDTBA-Ni. Mo reover, DDTBA-Ni phase was more appropriate for the separation of lower vol atile phenols. A similar property was exhibited by the metal complexes of P -DODTBA. A spiral glass column (2.1 mx3.2 mm i.d.) was prepared from 5% DDT BA-metal complex deposited on Chromosorb. By dynamic coating, wall-coated P -DODTBA-metal complex capillary columns (12 mx0.25 mm i.d.) were also prepa red as stationary phases for the separation of phenols. Factors affecting t he retention and the sample selectivity on both the packed column and the c apillary column were examined. The calibration graphs for phenol determinat ion were linear over the range of 64-1600 mu g ml(-1) (packed column) and 1 6-400 mu g ml(-1) (capillary column). The 2 sigma mass detection limits of most phenols are less than 30 ng for packed column and 4 ng for capillary c olumn. (C) 1999 Elsevier Science B.V. All rights reserved.