Liquid paraffin, impregnation with

Note Rhodamine B is a universal reagent that can be used on silica gel, talc, starch [5] and cellulose layers, just as on urea [1] or silver nitrate-impregnated [7] phases. Liquid paraffin-impregnated silica gel and RP layers are less suitable, since the background to the chromatographic zones is also intensely colored. It is often possible to increase the detection sensitivity by placing the plate in an atmosphere of ammonia after it has been sprayed or dipped, alternatively it can be oversprayed with sodium or potassium hydroxide solution. 

Biswas, S., Pathak, P.N., Roy, S.B. Manchanda, V.K. (2011) Uranium permeation studies from nitric acid medium across supported liquid membrane impregnated with PC-88A and its mixtures with neutral oxodonors in n-paraffin as carriers. Separation Science and Technology, 46 (4), 592-600. 

Silica gel plates are modified to form a reversed-phase sorbent by being impregnated with liquid paraffin, silicone oil, or fats. Reversed-phase plates of this type are used in the identification of steroid hormones [8,9]. Table 3.2 lists various other substances that have been used for impregnation [10,11]. Sorbents that are impregnated with amminium oxalate, ammonium sulfate, magnesium acetate, sodium acetate, and silver nitrate have one time or the other been commerically available. As an example, impregnated adsorbents have been used for the resolution of sulfa drugs [19]. 

Reversed-phase TLC also uses the common supporting facilities. In the laboratory, the nonpolar stationary phase can be produced by impregnating the layer (kieselguhr G or silica gel G) with long-chain hydrocarbons or liquid paraffin or by treatment with dimethyldichlorosilane (DMCS). Although commercial RP-TLC plates are available, so far it has been experimented with Ci8 plates only. 

The addition of any paraffin(ic) material was found to significantly reduce the rate of phosgene evaporation [ICI55]. The addition of a linear-chain paraffin (Cj -C, ) or kerosine (2 parts of solvent to 1 part of liquid phosgene) reduces the rate of evaporation to 20% of that of an untreated pool. The addition of an inert filler (dried sawdust) impregnated with paraffin was found to be as effective as adding the paraffin, but acted also as a filling material. If this is followed by the addition of an excess of hydrated lime (calcium... 

Silica gel GF254 impregnated with 5% v/v liquid paraffin in petroleum Citrate buffer pH4.2 methanol 3 1 [41]... 

Oil acts by extracting liposoluble substances. It is stirred vigorously to create an emulsion in the wine. This operation is repeated several times, until the oil is perfectly dispersed. When the mixture is allowed to rest, a layer of oil forms on the surface and is eliminated by careful racking. Liquid paraffin is mentioned in many books on this subject. It was not only recommended for eliminating unpleasant smells but also for isolating wine from the air in partly empty vats in order to protect it from acetic bacteria. In certain countries, solid paraffin discs, impregnated with allyl isothiocyanate, are used to create a sterile atmosphere. 

It should also be possible to isolate the individual tocopherols or their nitroso derivatives by reversed phase chromatography on chromatoplates (e.g., silica gel impregnated with liquid paraffin), similar to the paper chromatographic methods (Marcinkiewicz and Green, 1959). 

Silica gel impregnated with 5% liquid paraffin in petroleum ether is another stationary phase, which is sometimes used for the separation of peptides. The separations are performed using the mixture methanol-water (1 4, v/v) as mobile phase. 

Sliwiok, Podgomy, and Siwek " used TLC and high-performance liquid chromatography (HPLC) to compare the hydrophobicity of vitamin A derivatives (iA -trans reti-nic acid, ai -trans retinal, vitamin A acetate, and vitamin A palmitate). TLC was performed on RP-2 F254 and Kieselguhr F254 (impregnated with 10% paraffin oil in cyclohexane) with methanol-water (95 5, v/v). 

Kovacs-Hadady (1995) studied the retention behavior of barbiturates by overpressurized liquid chromatography (OPLC) on silica gel layers impregnated with paraffin or dodecyltrimethylammonium bromide and developed with mixtures of methanol and water. 

Toyo Roshi No. 50 impregnated with a 2% liquid paraffin soln. in ligroin Solvent... 

Lengyel et al studied the separation of methylchlorosilanes on different supports and with different liquid. Celite and Sterch-amol were both satisfactory supports but Termalite (firebrick) had a strong selective-absorption effect, resulting in asymmetric elution curves. Of the stationary phases tested (liquid paraffin, silicone oil, 1-chloronaphthalene, dibutylphthalate and nitrobenzene), those with the highest dipole moments were the most effective. Celite impregnated with 23% of nitrobenzene gave complete separation of a six-component mixture. 

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