Chromatographic Behavior of a Cholesteryl Myristate Stationary Phase in an Electric Field

Abstract

Changes in peak shape which accompany the imposition of an electric field were examined by moments analysis. Although peak maxima shifted signficantly, only slight changes were observed in the value of the peak mean. Column efficiencies calculated from the second central moment indicated that the field lowered the resistance to mass transfer, probably as a result of electric field-induced convection of the stationary phase.

Band broadening studies using parameters for an exponentially modified Gaussian

“…Apparatus. A large chromatographic oven described earlier (11) was used in this study. The temperature in the oven was controlled by a Thermatrol proportional controller (Hallikainen Instrument Co., Richmond, Calif.).…”

Gas Chromatographic Retention Characteristics of Different Polysiloxane Oligomers

“…Fig. 1 shows the results of such an experiment~ Description of the procedures for sampling and flow control for the high precision gas chromatographic analysis have been previously described (19). The temperature of the ••satur~tor chamber was limited to about 400C so as to minimize evaporation of some of the highly volatile solutes.…”

“…They related retention to oligomer chain-length, and they demonstrated the significance of sample-size effects and mixed retention mechanisms, especially for very small samples. A comparison of retention based on calculation of the first moment (peak mean) and peak maxima was made by Lorenz and other authors (11,(17)(18)(19). Their conclusions were that although the peak mean was more meaningful thermodynamically, its value was very difficult to obtain accurately under any one of the following conditions: bad tailing, very large or very small sample sizes, and low signal-to-noise ratio.…”

“…The high precision gas chromatograph previously described (19) was modified to provide more automated operation. A Valco gas sampling valve with a 5.0 ul internal sampling loop was used for on-column injection.…”

Vanadyl metal mesogen derivatives: an ESR study

“…A noticeable and useful characteristic of liquid crystals is that they can achieve a longrange orientational molecular order in the presence of either electric or magnetic fields [ l , 21. Because of this property liquid crystals have been widely used as solvents in a great number of studies, as well as in many applications where it is necessary to obtain molecular orientation of other substances. With that aim, liquid crystals have been used in NMR [3], EPR [4] and Mossbauer [5] spectroscopies as well as in other techniques such as gas chromatography [6].…”