SummarySingle, long columns (1-5 m) can be prepared efficiently using reversed phase packings (3-10 pm particle diameter). 1-m columns packed with 3 and 10 pm packing provide 1 10 000 and 50 000 theoretical plates, respectively. Very efficient columns can resolve highly complex mixtures and difficult-to-separate compounds. Temperature gradient elution is a powerful technique for LC with microbore columns.

The experimental results are represented in Figure 1 ; as in ref.[5], the log k'and Csaxes have opposite directions. Although only few values of solubility are available, the variations of log kvalues and log CS values of 2-hydroxynaphthalenc? are clearly seen to be parallel; some deviations are observed for the less accurately known low K and high Cs values. For 2,3-dihydroxynaphthalene only two Cs values are available in the range of good accuracy, so thatonlyageneral ideacan begainedoftheanalogiesoflog K and log Cs; however, the vertical distance between the plots is clearly much larger than for 2-naphthol. This is in accord with earlier observations [3]. The retention vs. eluent composition relationships are approximately linear, as is frequently observed for liquidlliquid and liquidlsolid systems of this type [7,8].The experimental results confirm the important role of solution effects for nonpolar adsorbents [4,9-141; however, for polar solutes the selectivity (A log K) is apparently attributable not only to differences of solubility (A log CS) but also to other factors.

No abstract

No abstract

SummaryThe low temperature effect has been investigated on a set of three different silica-gel micro columns with FC-78 as eluent. An open tubular micro glass capillary, a packed micro glass capillary, and a packed micro teflon column were examined. Temperature dependences of separation factors and theoretical plate numbers were determined. It appears that a decrease in column temperature improves chromatographic selectivity whilecolumn efficiencydecreases. The compensation temperatures were determined for these systems. The results suggest that the retention mechanism operative in the low temperature range is almost the same as that in the normal temperature range. However, the mechanism differs from that of reversed phase systems.