Effect of the Stationary Phase When Mobile Phases Are Identical

6 Effect of the Stationary Phase When Mobile Phases Are Identical 

An example of the difference between nominally identical precoated layers from different manufacturers has already been graphically described in Section 2.3. The discussions in this Section are concerned with precoated layers with different types of sorbent, all produced by one manufacturer. 

The newly introduced HPTLC-LiChrospher Si 60 F254S precoated plates in many cases show a still better separation efficiency than the HPTLC silica gel 60 precoated plates. For example. Fig. 12a (HPTLC silica gel 60) and Fig. 12b (HPTLC-LiChrospher Si 60254s) how the scanned chromatograms of eight pesticides, all in the solvent system petroleum ether 40-60 °C + acetone (70 + 30 ml, without saturation of the chamber) [13a]. Also in the analysis of frankincense (olibanum), better separations were obtained on plates precoated with spherical silica gel than on those precoated with irregularly shaped particles [13b-dj. 

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