Developing tank

When the solvent around the spot has evaporated, the plate is placed ertically in a glass developing tank (a cylinder for small slides) which contains a small quantity of the solvent and is lined with filter-paper dipping into the solvent the level of the latter is adjusted, preferably with a pipette, so that the lower edge of the absorbent layer is under the soh ent but the spot is above this level, and the top of the cylinder is then firmly closed. The solvent rises through the adsorbent layer, and the components of the mixture ascend at different rates depending on their affinities for the adsorbent. 

Lastly, it is worth mentioning that there are applications of two-or-more-step preparative TLC in solnble organic matter fractionations however, they are rarely described [4,86]. Each plate is developed successively in a series of solvents such as tetrahydrofurane, CHClj/MeOH (4 1 v v), toluene, and pentane such that the solvent front advancers approximately 4 cm with each successive solvent the plate dries up between the solvent, and the development tank atmosphere is allowed to equilibrate for at least 30 min after adding a new solvent, and before inserting the plates. Fractions represented immobile material in tetrahydrofurane (THE) and mobile compounds in successive solvents. 

Place the development solvent (l-propanol ethyl acetatexoncentrated NH4OH, 1 1 1) in the developing tank, and develop the chromatography plate so that the solvent migrates for 12 cm. 

The pure benzoyl isocyanide derivative is Anally obtained as red crystals (1.40-2.23 g, 50-80% yield, mp 78 °C) following thin-layer chromatography (TLC) on silica gel plates (40 x 20 cm) in a large developing tank (43 x 23 x 29cm) using 700 mL of (C2H5)20-petroleum ether (1 4) as eluent. The desired product is contained in the red band on the TLC plate. 

Iatroscan TLC-FID analyzer (e.g., model MKIII Iatron Laboratories) with Chromarod developing tank Filter paper, analytical grade 10-ml volumetric flask... 

Line a TLC developing tank with clean filter paper. Pour 97 3 1 (v/v/v) hexane/diethy 1 ether/formic acid (the solvent system) into the tank, wetting the entire paper. Incubate at room temperature until the tank is saturated with the solvent system (at least 1 hr). 

Although a Chromarod developing tank may be provided with the analyzer, any regular rectangular glass TLC tank can be used for development as long as the Chromarod rack fits (e.g., 20 x 20-crn). 

Immediately transfer the Chromarod rack into the equilibrated developing tank (step 1) and incubate 45 min at room temperature. 

Prepare three developing tanks (see Basic Protocol, step 1) using the following solvent systems ... 

To provide constant humidity, Chromarods that have been spotted with a lipid sample are incubated in a constant humidity chamber for a fixed period of time (10 to 15 min) to reach equilibrium before being transferred to a developing tank. A saturated sodium chloride solution is widely used to provide constant humidity, as saturated solutions of inorganic salts give... 

Cold room (4°C) or cold box Computer (PC or Macintosh) and printer Conical centrifuge tubes, 15- and 25-ml plastic Cuvettes, plastic disposable, glass, and quartz Darkroom and developing tank, or X-Omat automatic X-ray film developer (Kodak) Desiccators (including vacuum desiccators) and desiccant Dry ice... 

Film washer with hose attachment (the developing tank can often be used)... 

Processing time and temperature in the first developer is important and should be kept within +/— 1 degree. For this purpose a JOBO rotary processor is an excellent choice. If one is not available, try placing the developing tank in a water bath to maintain the processing temperature. 

JOBO AG (darkroom equipment manufacturers, including daylight development tanks for large format film), Kolner StraBe 58, 51645, Gummersbach, Germany t +49 (0)2261 545-0 www.jobo.com. 

Thin layers of powdered cellulose, silica gel, alumina, ion-exchange or gel-permeation material supported on glass plates, plastic sheets or aluminium foil development tanks components sometimes examined by reflectance or transmittance densitometry or removed for spectrometric analysis. 

The development tank for plates of (2 cm x 5 cm) a clean, dry beaker (100 mL) covered with a watch-glass is ideal. The eluting solvent should be about 3 mm deep and filter paper should be placed in the tank to saturate the tank atmosphere with solvent vapour (Fig. 32.11). 

Prepare the TLC development tank using a clean, dry beaker, as shown in Fig. 32.11, and allow it to equilibriate for 10 minutes. 

Lower the plate into the developing tank, holding it by the edges and make sure that the eluent does not cover the base line. If it does, discard the plate, prepare another and empty some eluent from the tank. 

The universal TLC facilities are utilized plates, adsorbents, microcapillaries, or micropipettes for sample application, development tanks, detection spray reagents, devices for spraying, and densitometers for quantification. Plates are either commercially precoated or handmade. Silica gel G (G, for gypsum as a binding substance), silica gel H (no binding substance) and, rarely, alumina and kieselguhr, form the thin-layer stationary phases. Complete sets of devices necessary for the preparation of handmade plates are commercially available. After the silica gel slurry is spread on the plates, they are left to dry in the air for at least 24 hr and shortly in an oven at 110°C. The plates are then ready for either direct use or for modification of the layer. From the great variety of precoated plates, which are commercially available and preferred nowadays, silica gel plates and plates with layers... 

Erythromycin and erythromycin estolate can be separated and quantitated by thin layer chromatography.Samples or standards should approximate 50 meg erythromycin estolate and 5-10 meg erythromycin base when spotted on silica gel G-25 plates. Approximately 120 ml of the developing solvent (methanol A.R.) is placed into the developing tank and allowed to equilibrate. The plate is developed until the solvent is approximately 15 cm from the origin The plate is removed and allowed to air dry. Antibiotic spots are visualized by spraying the plate with a fresh mixture of 95 ethanol/anis-aldehyde/conc. sulfuric acid, 90 5 5(v/v) followed by heating of the plate at 110 C for 10 minutes. The Rf values of erythromycin estolate and erythromycin base are approximately 0.7 and 0.35 respectively. 

E Ethyl acetate-n-butyl ether-ammonium hydroxide (60 35> ) Fj - F2-> Developing tank with 110 ml. solvent plus a beaker containing 10 ml. 28% ammonia F Petroleum ether (30-60°C.)... 

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