Drying after development

This test is conducted to determine the proper amount of time a TLC plate should be dried after development. It is often found that a range of drying time is acceptable. However, a plate that has not dried long enough sometimes shows an adverse effect when sprayed by a derivatizing agent. 

But continued PAS work found concentration differences of samples located across a single plate, and it seemed to be related to the way the layer was dried after development [9], The different drying routines investigated were those most commonly used by all chromatographers (1) simple air drying (in the hood), (2) with a stream of warm air (hair dryer or similar), and (3) in a forced air oven at 50°C. The most reproducible was the latter. This is certainly because the layer is heated more evenly than by the other drying techniques, a point to be remembered for inclusion in any new protocol. Continued work by Prosek et al. [10] on this topic allowed the... 

Compound degradation on the plate can be checked by two-dimensional development of a mixture with the same mobile phase, as described in Chapter 14 (Figures 14.2-14.4). All of the zones will lie on a diagonal straight line if no decomposition occurs during development. The layer should be dried after development under conditions that completely remove the mobile phase constituents but do not volatilize sample components. 

The influence of sedimentation process on the value of reduced thickness of various dry powder developers is carried out in our experiments. Fig 1 illustrates the pictures of real developer s layers before (a, c) and after (b, d) penetrant application. The pictures were... 

The aim of this work is the development of pyrene determination in gasoline and contaminated soils. For this purpose we used room temperature phosphorescence (RTP) in micellar solutions of sodium dodecylsulphate (SDS). For pyrene extraction from contaminated soils hexane was used. Then exttacts earned in glass and dried. After that remains was dissolved in SDS solution in the presence of sodium sulphite as deoxygenation agent and thallium (I) nitrate as heavy atom . For pyrene RTP excitation 337 nm wavelength was used. To check the accuracy of the procedures proposed for pyrene determining by RTP, the pyrene concentrations in the same gasoline samples were also measured by GC-MS. 

Alkaloids Sodium borohydnde solution is applied after the sample solution The plate is dried and developed after a few minutes [2, 25]... 

Imperatorin Apply sample solution, moisten with chloroform, place in the vapors of 10% bromine in chloroform and then dry and develop after an appropriate reaction time. Tribromoimperatorin is produced. [16]... 

Alcohols Apply sample solution, then nitrophenyl isocyanate solution (10% in benzene) Dry after reacting and develop [72]... 

Repeated chromatography in a third dimension after completion of two-dimensional development. Here, development in the first, second, and third dimensions can be envisaged as occurring on three plates arranged in the form of a cube the plate is again dried between developments. 

On the basis of the principle of grafted TLC, reversed-phase (RP) and normal-phase (NP) stationary phases can also be coupled. The sample to be separated must be applied to the first (2.5 cm X 20 cm) reversed-phase plate (Figure 8.16(a)). After development with the appropriate (5ti 5yi) mobile phase (Figure 8.16(b)), the first plate must be dried. The second (20 cm X 20 cm) (silica gel) plate (Figure 8.16(c)) must be clamped to the first (reversed-phase) plate in such a way that by use of a strong solvent system (Sj/, SyJ the separated compounds can be transferred to the second plate (Figure 8.16(d)). Figure 8.16(e) illustrates the applied, re-concentrated... 

TLC plates Aluminium oxide 150 F254 (Merck) before application of the samples the layer was developed twice to its upper edge with methanol — ammonia solution (25 %) (50 + 50) to pre-cleanse it and then dried after each development at 120 °C for 30 min. 

After the preparative plate has been developed and the mobile phase removed, the separated compoimds mnst be located prior to their recovery from the plate. Mobile phase removal after development shonld not involve heating if the compound of interest is thermally labile place the plate in a desiccator for vacuum drying. 

Bioluminescence can be used for spedfic detection of separated bioactive compounds on layers (BioTLC) [46]. After development and drying the mobile phase by evaporation, the layer is coated with microorganisms by immersion of the plate. Single bioactive substances in multicomponent samples are located as zones of differing luminescence. The choice of the luminescent cells determines the specificity of detection. A specific example is the use of the marine bacterium Vibrio fischeri with the BioTLC format. The bioluminescence of the bacteria cells on the layer is reduced by toxic substances, which are detected as dark zones on a fluorescent background. BioTLC kits are available from ChromaDex, Inc. (Santa Ana, CA). 

After development, the plate is again dried in a stream of nitrogen, the individual zones scraped off, and the stationary phase suspended in acetone or a similar solvent for some minutes. After filtration, the process is repeated until the stationary phase... 

For the development of an appropriate strategy for cleavage from the novel syringaldehyde resin, the authors adapted a previously elaborated solution-phase model study on intramolecular Diels-Alder reactions for the solid-phase procedure (Scheme 7.60). The resulting pyridines could be easily separated from the polymer-bound by-products by employing a simple filtration step and subsequent evaporation of the solvent. The remaining resins were each washed and dried. After drying,... 

The organic phase was evaporated and the residue dissolved in chloroform. A portion of the chloroform solution was spotted on silica gel plates which were then developed in chloroform methanol ammonia (89 10 1). After development, the plate was air dried and sprayed with a 2M aqueous solution of ammonium bisulfate. After the plate was air dried for 1 hour, the fluorescent spot representing triprolidine was quantitated with a spectrodensitometer in the reflectance mode with 300 nm excitation and emission above 405 nm. With... 

After 2 to 3 h (the longer the better), remove the paper, quickly mark the solvent front with a pencil, and hang the paper in a fume hood to dry. After drying for 5 to 10 min, spray the developed portion with ninhydrin solution (0.1% ninhydrin in butanol or isopropyl alcohol). Allow to dry for 10 min. Then place it in a drying oven at 100°C for 5 min. Amino acid spots will be violet to blue in color. 

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