Impregnation gels impregnated with metal salt

Sulfonamides can be analyzed both by NP TLC (on silica gel, alumina, polyamide, and Florisil layers) and by RP TLC (on silanized sihca, RP-2, RP-8, and RP-18 layers). Some sulfonamides have been separated by TLC on silica or polyamide impregnated with metal salts. Both aqueous and non-aqueous eluents are applied. Detection of sulfonamides can be performed on fluorescence layers at 254 nm and after derivatization with, for instance, fluorescamine solution at 366 nm. 

Gels Impregnated with Metal Salt Solutions... 

To obtain composites of carbon with metal nanoparticles, organic gels can be impregnated with metal salt solutions before drying and pyrolysis processes... 

We also prepared supported catalysts by the impregnation of silica gel in isopropanol with metal salt, followed by its decomposition under heating (Me-Sup). 

For practical (real) catalyst systems, precipitation, ion exchange, impregnation and sol-gel processing procedures are used. In precipitation methods, a hydroxide or a carbonate of a metal may be precipitated from a solution of a metal salt onto the support material held in the solution. Thus, a copper-silica catalyst may be prepared using a Cu-nitrate solution in which silica is suspended. Additives of any alkali cause the precipitation of copper hydroxide onto the silica support. This is then dried and normally reduced in hydrogen at moderate temperatures ( 400-500 °C) to form the catalyst. In co-precipitation techniques , the support is precipitated simultaneously with the active catalyst. In the ion-exchange method, for example, highly dispersed Pt on... 

The usual preparation of supported micrycrystalline samples by the incipient wetness technique involves the impregnation of a support, e.g., silica gel or alumina, with a solution of a metal salt to form a thick slurry that is subsequently dried and sometimes heat-treated. 

Sfiica impregnated with saturated and unsaturated hydrocarbons (squalene, paraffin oil), silicone and plant oils, complexing agents (silver ions, boric add and borates, unsaturated and aromatic compounds), tigands (EDTA, digitonin), and transition metal salts silanized silica gel impregnated with anionic and cationic surfactants Cross-linked, polymeric dextran gels (Sephadex)... 

Other type of complexes have also been used for the oxidation of hydrocarbons. For instance, Fujiwara and coworkers employ a coordinated complex of palladium with o-phenanthroline as an efficient catalyst for the direct conversion of benzene into phenol. Moro-oka and coworkers use an oxo-binuclear iron complex, whereas Machida and Kimura work with macrocyclic polyamines. Sasaki and coworkers employ Pd-Cu composite catalysts, which are prepared by impregnating the respective metal salts on silica gel. 

Sarin and other nerve agents may be removed from cleaning organic solvents (trichlorotrifiuoroethane and its mixtures) by such adsorbents as Fuller s earth, activated alumina, silica gel, and silica gel impregnated with a metal salt (Fowler and Mcll-vaine 1989). Hydrolysis with water or dilute alkalies should yield products of low toxicity. 

A number of methods have been reported in the literature for improving the thermal stability of acrylic fibers. For example, impregnating wet-spun fibers in the gel state with salts of metals from group II in the periodic table of the elements [496] or sodium sulfide solution [487] have been reported. Also, dried fiber can be impregnated with sulfuric acid solutions of formamide [488], phosphates or borax [489], or organotin salts [490]. 

From Na and Other Inert Gases. Adsorption isotherms for PH3 in mixtures with Na at 293 K were determined on various types of silica gel, activated carbon, and zeolites [3]. The removal from inert gases can be achieved by contact with silica gels [4], zeolites [4, 5], or activated carbon impregnated with CH3CN, picric acid, or maleic acid [4]. The adsorption on activated carbon pretreated with iodine compounds and sulfates or nitrates of ammonium and metals was used in [6]. Cu- or Ag-modified molecular sieves [7] or a soda-lime bed, which may contain nitrite salts, were also used as adsorbents [8]. The removal of PH3 by an aqueous solution of LiCl and HCIO4 was mentioned [9]. Its removal by oxidative methods is described in Section 1.3.1.5.4, p. 222. 

Bhushan and Ali (1987) tested amino acid separations on silica gel layers impregnated with various metal salts. Bhushan and Reddy (1989) reported the separation of phenylthiohydantoin (PTH) amino acids on silica gel with new mobile phases. Laskar and Basak (1988) de.scribed a new ninhydrin-based procedure that produced different colors and good sensitivity for amino acid detection. Bhushan and Reddy (1987) reviewed the TLC of PTH amino acids. Gankina et al. (1989) described a unidimensional multistep silica gel HPTLC method for the separation and identification of PTH and dansylamino acids. Bhushan et al. (1987) developed numerous solvent systems for effective separations of 2,4-dini-trophenyl-(DNP) amino acids. Bhushan (1988) reviewed the TLC resolution of enantiomeric amino acids and their derivatives. Kuhn et al. (1989) reported the amino acid enantiomer separation by TLC on cellulose of d- and L-tryptophan and methyltryptophan. Guenther (1988) determined TLC-separated enantiomers by densitometry. 

The same method has been used successfully to prepare plates with silica gel, silica gel-polyamide, cellulose, and these adsorbents impregnated with a variety of reagents including HDEHP, TOPO, 8-hydroxyquinoline, dibenzoyl methane, and several metal salts (13-30). Brucine (20) and tartaric acid (22) were also mixed in slurries of silica gel as impregnating reagents to resolve enantiomers of amino... 

Certain difficulties as mentioned in Section II.3, in resolving or identifying various PTH-amino acids combinations have successfully been removed with the application of silica gel layers impregnated with various metal salts including transition metals and other reagents such as (+)-tartaric acid and (-)-ascorbic acid for the identification and resolution of PTH-amino acids in multicomponent mixtures and enantiomeric mixtures (18,19,21,22,26,30). The methods reported provide very effective resolution and compact spots (by exposure to iodine vapors) and can be applied to the identification of unknown PTH-amino acid some of these are given in Tables 18-20. Some of the successful solvent systems for TLC of PTH amino acids on impregnated plates are summarized in Table 20A. 

---