Drying cupboard

Emetine andcephaeline, the two major alkaloids of ipecacuanha, begin to fluoresce after treatment with iodine vapor [254], The molecular iodine, which acts as a quencher, must be removed by heating in the drying cupboard or on a hotplate... 

Acetanilide, p-chloro-acetanilide, 2,5-dichloro-acetanilide Apply sample solution and treat with chlorine vapor in the trough chamber for 20 s, then heat to 60°Cfor 5 min in a ventilated drying cupboard. Various chlorination patterns are produced. [44]... 

Since it still is not a simple matter to heat a TLC plate really homogeneously there is a danger of reaction inhomogeneities on the plate. The usual types of apparatus employed for heat production and transfer are drying cupboards, hotplates and IR sources. The success obtained using microwaves has been modest up to now. 

The chromatograms are dried in a stream of cold air (alkaloids 110 —120°C for 25 min in drying cupboard) and placed for 15 min in a twin-trough chamber — in the case of alkaloids while still hot — whose second trough contains 10 ml 25% ammonia solution. 

Valepotriates are detected by placing the chromatogram 0.3 mm from a TLC plate sprayed with cone, ammonia solution (sandwich configuration layer to layer), fastening with clips and heating to 110°C in a drying cupboard for 10 min [12]. 

Detection and result The chromatogram was heated in the drying cupboard to 110 —120°C for 25 min and immediately placed — while still hot - in a twin-trough chamber, whose second trough contained 10 ml 25% ammonia solution, for 15 min. The chromatogram was then immersed for 2 s in a solution of liquid paraffin — n-hexane (1 + 2). 

The chromatogram is freed from mobile phase in the drying cupboard (10 min, 120°C) and immersed for 1 s in the reagent solution or sprayed homogeneously with it until the plate starts to appear transparent it is then dried briefly in a stream of warm air and heated to 125 —130 °C for 45 min. 

The developed chromatogram is freed from mobile phase by heating to 110°C for 10 min in the drying cupboard. It is allowed to cool and immersed for 1 s in or sprayed homogeneously with the reagent the plate is then examined (while still moist). 

Detection and result The chromatogram was freed from mobile phase in the drying cupboard (5 min 100 "C), immersed in the freshly prepared dipping reagent for 1 s and then heated to 100"C for 10 min. 

Variant I The chromatogram is dried in a stream of warm air or in the drying cupboard (10 min, 120 °C), cooled to room temperature and either sprayed with spray solutions la and lb one after the other (with brief drying in a stream of cold air in between) [1] or sprayed with a mixture of equal volumes of these two spray reagents until the layer begins to be transparent [2, 4]. 

Immerse the dried chromatogram for 1 s in the reagent solution and then heat to 40 - 50 °C in the drying cupboard for 10 min. 

In the simplest case the developed chromatograms are heated to the required temperature on a hot plate (Fig. 19) or in a drying cupboard. More rarely infrared heaters are used to heat the system [2]. Gas chromatograph ovens can be used if exact adjustment of the temperature is required [3]. 

The plate should be heated as rapidly and as evenly as possible after the first spraying step this is best done on a thick preheated aluminium plate in a drying cupboard equipped with ventilation allowing the nitric acid vapors to be removed using a water pump vacuum. Sodium dithionite is better than titanium(III) chloride or tin(II) chloride for the reduction of the nitro derivatives of amitrityline and nortriptyline. 

The dried chromatograms are first sprayed homogeneously with reagent 1, then dried for 2 to 3 min in the air and for ca. 10 min at 60 C in a drying cupboard until the pyridine has completely evaporated. Afterwards they are briefly sprayed with a little hydrochloric acid (25%) and exposed to nitrous fumes (reagent 2) for several minutes. Finally after removal of the excess nitrous fumes in a stream of cold air the chromatograms are sprayed with reagent 3. 

Note If the mobile phases contains formamide the chromatograms should be freed from it by heating to 130-140 °C in the drying cupboard for 1 h before applying the reagent [6]. 

Detection and result The chromatogram was dried for 5 min in a stream of cold air and immersed twice for 10 s - with brief intermediate drying in a stream of cold air - in the dipping solution and then immediately heated to 115 °C for 15 min in the drying cupboard the TLC plate was only to be supported on its side on two metal tracks. After cooling to room temperature the chromatogram was immersed for 1 s in a solu-... 

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