Production of constant humidity in closed vessels

Saturated salt solution containing a large quantity of undissolved salt Relative humidity over the solution (20 °C) [%] 

Direct optical evaluation under 254-nm UV light using the TLC-Scanner II (CAMAG) 

Using similar techniques, preconditioning can be performed by treating plates with molecules of organic compounds (e.g. solvents) or with acids and bases, sometimes after the sample has been applied, and this often improves the chromatographic result. 

Separation on silver nitrate layers is based on complex formation by the Ag ions with the Jt-electrons of one or more double or triple bonds of the substances being separated and depends on the strength of the bond [22]. As an example, Kraus describes the separation of some CIO alcohols which cannot be separated by either partition or adsorption chromatography without impregnation [21, experiment 13.9.9]. 

The monograph Doxycycline in the DAB 96, 2nd addendum 1993, specifies a layer sprayed with a solution of sodium edetate solution for the identification of this substance. However, the problems begin with the choice of the layer, as DAB states the test is performed with the aid of TLC (V.6.20.2) using a layer of sUica gel H R. The DAB, as always, specifies TLC plates produced in-house, as sUica gel H is a loose sorbent without additions of extraneous binders (see Table 2), where R represents a sUica gel with a mean particle size of 15 pm. 

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Table 5 Production of constant humidity in closed vessels...

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