Location and Labeling of TLC Developing Chambers

In rare cases, however, problems can arise from the continuous circulation of atmospheric air even when the work is performed on the laboratory bench. The quality and reproducibility of the separation in TLC analyses can be improved by placing a styrofoam hood of suitable size over the TLC chamber during the development [62]. 

Direct simlight should not be allowed to fall on the TLC chamber, as this can lead to temperature effects and catalytic interactions between the samples and the sorbent. It may therefore be necessary to work in subdued light for some hours. The treatment of sensitive samples is described in Section 10.2. 

For teaching in a pharmacy or in laboratory areas where TLC is demonstrated only occasionally, only one experiment usually has to be performed, i.e. only one developing chamber is used in a given period of time. In this case the chambers do not need to be marked, as there is no possibility of a mix-up. This is not so if several TLC plates are to be developed in parallel or within a limited time period, when several chambers are standing on the laboratory bench at the same time. In this case it is important to mark them properly. If the chambers (and therefore solvent systems) become mixed up, all the previous preparative work is futile, and an entire working day can be wasted. 

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