Whatman HPTLC plates consist of 4.5 µm particle size silica gel plus an inert binder in a uniform 200µm layer on glass. They exhibit product characteristics typical of Whatman silica gel media: Narrow particle size distribution, homogeneity and overall uniformity. The results are performance and reproducibility, giving you the ultimate in TLC resolution and sensitivity. 17210-21 through -32 have linear-K preadsorbent spotting area.