Rhodamine 6G reagent

Storage Both reagent solutions may be stored for an extended period. 

Rhodamine 6G accumulates in lipophilic chromatogram zones giving rise to a stronger fluorescence than in their surroundings. 

Note Rhodamine 6G is a universal reagent which can also be incorporated in the TLC layers [4, 9] or added to the mobile phase [4], The spray reagent can also be made up in water [8], acetone [4, 6] or ammonia solution (c = 2.5 mol/1) [5]. The visual detection limit is most favorable when the water from the mobile phase or the detection reagent has not completely evaporated from the layer. This can be recognized by the fact that the background fluorescence has not turned from red to pink [4]. 

It is often possible to increase the detection sensitivity in visible light by exposing the dipped or sprayed chromatogram to ammonia vapors it can also be sprayed with caustic soda or potash solution. When this is done the fluorescence intensity is reduced on silica gel layers and increased on RP ones. 

The reagent can be employed on silica gel, kieselguhr, cellulose and Florisil layers these can also be impregnated, if desired, with silver nitrate. 

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The reaction was not particularly sensitive on paraffin-impregnated kieselguhr layers because of background coloration. For quantitation it was better to use the five-fold more sensitive rhodamine 6G reagent (q.v.). 

The following are amongst the reagents that have been reported as being added to the mobile phase acids for quinine alkaloids [184], ninhydnn for amino acids [185 — 187], fluorescamine for biogenic amines [188] Fluorescein sodium [189], dichlorofluorescein [190], rhodamine 6G [191], ANS reagent [192] and bromine [193] have all been descnbed as additives to mobile phases... 

The reagent used for the deteetion may be speeifie to a special functional group or specific lipids or may be a nonspecific reagent that makes all hpids visible. The most commonly used reagent that is nonspecific for any lipid group is 0.1% (w/v) 2, 7 -dichlorofuorescein in 95% methanol. This is mainly useful when the plates have been developed in acidic solvents. The lipid spots or bands can be visualized as yellow spots or bands under UV light. After the plates are developed in alkaline solvents, an aqueous solution of Rhodamine 6G (0.01%) can be used, and lipid spots can be seen as pink spots under UV. Because both these methods are nondestructive, they can be effectively used in PTLC so that the separated sample bands can be scraped off and used for further analysis. 

Hydrogen peroxide was determined with fmol detection limits by using rhodamine 6G and pyrimidopyrimidine derivatives as fluorescent enhancers. The method employing the latter reagent was applied to cola drinks [92], Sensitive... 

Another sensitive colorimetric procedure is that of Mackenzie et al (1967), which utilizes the dye Rhodamine B to form benzene-soluble complexes with fatty acids. Nakai et al. (1970) developed a rapid, simple method for screening rancid milk based on the foregoing procedure. The test is said to detect rancid milk with an ADV above 1.2. Like the copper or cobalt soap method, the Rhodamine B reagent is also limited to the longer-chain fatty acids. Kason et al (1972) used the method employing Rhodamine 6G of Chakrabarty et al (1969) to investigate... 

Other nondestructive detection methods use iodine vapors or iodine-potassium iodide reagents (Mylius s reaction). Yellow, orange, or brown zones will appear on the layer. The zones will have to be marked, because the iodine will eventually evaporate. The sensitivity of the iodine test can be greatly increased by the use of layers containing rhodamine 6G. Most of the steroids are recovered unchanged af-... 

Rhodamine B (formula 4.29) is a xanthene basic dye [72]. Other reagents in this class are Rhodamine 3B (Ethyl Rhodamine B) (the ethyl ester of Rhodamine B) [73], Butyl Rhodamine B (the butyl ester) and Rhodamine 6G (formula 4.30). 

Other organic reagents recommended for determining chromium include phenylfluorone [49] and o-nitrophenylfluorone (in the presence of CTA) (e = 1.1-10 at 582 nm) [50], Methylene Blue (e = 8.3-10" ) [51], Pyrogallol Red [52], morin [53], and 2,2 -diquinoxalyl [54]. Chromium was also determined by a sensitive method based on the ion-associate of Cr(VI) with Rhodamine 6G in aqueous solution containing poly(vinyl alcohol) [55], and after extraction into toluene [56]. 

Among other organic reagents for germanium, Bromopyrogallol Red is to be mentioned [54]. The ion associate of the Ge complex with Bromopyrogallol Red and Rhodamine 6G is floated with toluene, then dissolved in acetone (e = 2.6-10 ) [55]. 

Hydrochloric acid ( 1 A/) is a suitable medium for formation of the associate. The concentration of tin(II) should be 0.02-0.04 M, and Rhodamine 6G should be in 50-fold excess with respect to Pt. At higher SnCh and dye concentrations the absorbance of the reagent blank increases. The amount of DIPE used in flotation has no effect on the Pt separation efficiency. The time of shaking should not be shorter than 1 min. After the washing with 2 portions of 1 M HCl the absorbance of the reagent blank is not higher than 0.05. 

Spray solution Storage Substances Dissolve 100 mg rhodamine 6G in 100 ml ethanol (96%). Both reagent solutions may be stored for an extended period. Rhodamine 6G (C.l. 4S160) Method Layer Ascending, one-dunensional development in a trougli cliam- ber. HPTLC plates RP-18 without fluorescence indicator (Merck). 

Rhodamine 6G accumulates in lipophilic chromatogram zones giving rise to a stronger fluorescence than in their surroundings. Detection and result The chromatogram was freed from mobile phase and im-mersed for 1 s in the reagent solution. Arachidic acid (hRf 35—40), steanc acid ... 

It has been reported that y3-CD could improve the selectivity of the color reactions of various metal ions with triphenylmethane, xanthene acid dyes and some other coloring reagents. The effect of fi-CD on the association compound system of metal (Mo, Zn, Co)-thiocyanate basic dyes such as malachite green, crystal violet, rhodamine B, rhodamine 6G and butyhhodamine B, has been investigated and the result shows that /3-CD could contribute to a more sensitive and stable system which improve the solubility of the basic dyes and produce a favorable microenviromnent for the color reactions [63]. /3-CD could be employed to solubilize the 1,2-amino anthraquinone in water due to the formation of inclusion complex which acts as a ligand for metal ions could be used for the determination of palladium at trace levels by spectrophotometry. In the spectrophotometric determination of microamounts of Zn based on the Zn-dithizone color reaction, -CD could increase the apparent molar absorptivity at 538 nm by 8.37 times. In the presence of cr-CD, the determination sensitivity of copper in leaves based on the color reaction of Cu(II) and mesotetrakis (4-methoxy-3-sulfophenyl) porphyrin was enhanced by 50% in the spectrophotometric analysis [64,65]. 

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