Extra Column Dispersion - The Use for Low Dispersion Instrumentation with Small Bore Columns to Obtain Ultra High Efficiencies. > Page 65
An example of a separation by exclusion of an aromatic hydrocarbon mixture is shown in figure 33. The separation was carried out by size exclusion using silica gel as the exclusion media, and THF as the mobile phase. The efficiency of the column was 650,000 theoretical plates one of the highest column efficiencies so far reported.. The separation took about 10 hr. and base line separation was obtained for a difference between consecutive solutes of only two methylene groups (a molecular weight difference of only 30 i.e. 7%). The LC small bore chromatographic column, used in conjunction with low extra column dispersion instrumentation, is seen to begin to approach the performance of a low resolution mass spectrometer.
The separation of a sample of cinnamon bar oil is shown in figure 34.
Column Length 10 m, column I.D. 1 mm, packing Partisil Silica Gel, 20 mm, mobile phase 3% v/v ethyl acetate in n-heptane, flow rate 38 ml/ min., sample volume 0.5 ml, efficiency 160,000 theoretical plates
Figure 34. Chromatogram of Cinnamon Bark Oil