REPORT
using short lengths for fast opera tion. Realization of the importance of the amount of liquid is providing better efficiencies in many cases. The comparison of theoretical plates between packed and capillary col umns is now understood and has been explained. It is recognized that they can mean radically dif ferent things with regard to the separation achieved and should not be compared directly. The use of tubular columns is increasing. There is no reason to expect any thing but a continuation of the trend. Glass and Metal Bead Columns. There may be no real justification for treating glass bead columns separately. However, they seem to combine packed column geometry with tubular column coating of a hard surface and thus to lie some where between the two in an area by themselves. They were origi nally studied because of their welldefined surface area. During the past year their popularity has in creased considerably. They are a special purpose column designed for working well below the boiling point with samples which would be adsorbed strongly by normal sup ports with correspondingly low loadings. They have a definite future for these specialized prob lems. Cooke has shown that if they are operated under optimized flow conditions, the increased sep aration factors at the lower tem peratures provide chromatograms equivalent to the normal packed columns.
WILD* M20
MICROSCOPE
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Conclusions
Column efficiency vs. solvent ef ficiency is an old argument which was long ago won by column ef ficiency. Yet no matter how much we worry about the mechanics of the partitioning process the dif ference in partition coefficients is still very important. For the really difficult separation, optimum effi ciency will do wonders, but fre quently some time spent optimizing the liquid phase will yield equal or better results more easily. We have to have both to carry gas chroma tography into the problems· of the future. I hope we will continue to see the work from both viewpoints. Circle No. 130 on Readers' Service Card
H E E R B R U G G Circle No. 152 on Readers' Service Card
VOL. 33, NO. 8, JULY 1961
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31 A
