Transfer Solution - Paper PC - TLC

Very dilute solutions which contain little substance, are best concentrated, i. e., enriched, in a preliminary procedure. For this, the solution can be spotted on to a tongue-shaped piece of filter paper (Fig. 54b). A stream of warm air accelerates evaporation of the solvent [440]. The ring-oven technique may also be employed [604]. In order to transfer the relatively large substance spot to TLC, the paper tongue is placed in a bowl filled with solvent (Fig. 54 b). The substance is washed into the tip of the tongue. It can be transferred from here to the TLC start point in the simple way illustrated in Fig. 54 c. 

Note Occasionally in trace analysis a particular substance must be concentrated on the TLC plate itself. Two-dimensional development of a substance applied in band form, is useful here. The substance of the particular band is displaced into the region of the front in the second dimension by using a strongly polar solvent [445]. 

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