Indicator fluorescent

This analysis, abbreviated as FIA for Fluorescent Indicator Adsorption, is standardized as ASTM D 1319 and AFNOR M 07-024. It is limited to fractions whose final boiling points are lower than 315°C, i.e., applicable to gasolines and kerosenes. We mention it here because it is still the generally accepted method for the determination of olefins. 

Nevertheless, this type of analysis, usually done by chromatography, is not always justified when taking into account the operator s time. Other quicker analyses are used such as FIA (Fluorescent Indicator Analysis) (see paragraph 3.3.5), which give approximate but usually acceptable proportions of saturated, olefinic, and aromatic hydrocarbons. Another way to characterize the aromatic content is to use the solvent s aniline point the lowest temperature at which equal volumes of the solvent and pure aniline are miscible. 

Hydrocarbon groups (FIA method) NF M 07-024 ISO/DIS 3837 ASTM D 1319 Chromatography on silica gel with fluorescent indicators... 

Ecole Nationale Superieure du Petrole et des Moteurs Formation Industrie end point (or FBP - final boiling point) electrostatic precipitation ethyl tertiary butyl ether European Union extra-urban driving cycle volume fraction distilled at 70-100-180-210°C Fachausschuss Mineralol-und-Brennstoff-Normung fluid catalytic cracking Food and Drug Administration front end octane number fluorescent indicator adsorption flame ionization detector... 

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

Reference G.F. Kirkbright, Fluorescent Indicators, Chap. 9 in Indicators, E. Bishop (ed.), Pergamon Press, Oxford,... 

Filtered-Particle Inspection. Solids containing extensive inteiconnected porosity, eg, sintered metallic or fired ceramic bodies formed of particles that ate typically of 0.15-mm (100-mesh) screen size, are not inspectable by normal Hquid penetrant methods. The preferred test medium consists of a suspension of dyed soHd particles, which may be contained in a Hquid vehicle dyed with a different color. Test indications can form wherever suspensions can enter cracks and other discontinuities open to the surface and be absorbed in porous material along interior crack walls. The soHd particles that form test indications ate removed by filtration along the line of the crack at the surface where they form color or fluorescent indications visible under near-ultraviolet light (1,3). 

Recrystd from water and dried for 12hours in a vacuum at 110°, or 24hours in a vacuum at 70°. The purity was assessed by TLC on cellulose with a fluorescent indicator. [Taguchi, J Am Chem Soc 108 2705 1986 Tabushi et al. J Am Chem Soc 108 4514 1986 Orstam and Ross J Phys Chem 91 2739 1987.]... 

This property can be applied to the detection of substances that absorb in the UV region For on layers containing a fluorescent indicator or impregnated with a fluorescent substance the emission is reduced in regions where UV-active compounds partially absorb the UV light with which they are irradiated. Such substances, therefore, appear as dark zones on a fluorescent background (Fig. 4A). 

Organic fluorescence indicators for aluminium oxide, silica gel and cellulose layers (code F366, UV366) include ... 

The scintillators are a special type of fluorescence indicators they are employed for the fluorimetric detection of radioactively labelled substances. They are stimulated by ) -radiation to the emission of electromagnetic radiation and will be discussed in Volume 2. 

It is known that not all reactions proceed in the same manner on all adsorbent layers because the material in the layer may promote or retard the reaction. Thus, Ganshirt [209] was able to show that caffeine and codeine phosphate could be detected on aluminium oxide by chlorination and treatment with benzidine, but that there was no reaction with the same reagent on silica gel. Again the detection of amino acids and peptides by ninhydrin is more sensitive on pure cellulose than it is on layers containing fluorescence indicators [210]. The NBP reagent (. v.) cannot be employed on Nano-Sil-Ci8-100-UV2S4 plates because the whole of the plate background becomes colored. 

The reasons for the above phenomena are to be found in differing configurations of hydrogen bonds, the effect of pH, differences in the structures of fluorescence indicators and binders and differences in surface area. For example, silica gel 60 possesses a surface area of 500 m /g [211] while that of Si 50 000 lies below 5 m /g [212],... 

Note The reagent can also be applied before chromatography e.g. by impregnating the layer, which should preferably be free from fluorescent indicator it is not eluted by most mobile phases [4],... 

Note In the case of HPTLC plates the detection limit for the visual recognition of the violet = 530 nm) colored chromatogram zones was 20 ng per chromatogram zone. With the exception of the two tetrahydrosteroids the cor-ticosteriods could be detected on TLC plates with fluorescent indicators by reason of fluorescence quenching (Fig. 1 A). Figure 2 illustrates the absorption scans of the separations illustrated in Figures 1A and 1B. 

When staining with ninhydrin the appearance of colors of various hues on TLC layers with and without fluorescence indicators is probably a result of complex formation between the ninhydrin zones and the cations of the inorganic fluorescence indicators. 

Layer HPTLC plates RP-18 without fluorescence indicator... 

The intensity and colour of the fluorescence of many substances depend upon the pH of the solution indeed, some substances are so sensitive to pH that they can be used as pH indicators. These are termed fluorescent or luminescent indicators. Those substances which fluoresce in ultraviolet light and change in colour or have their fluorescence quenched with change in pH can be used as fluorescent indicators in acid-base titrations. The merit of such indicators is that they can be employed in the titration of coloured (and sometimes of intensely coloured) solutions in which the colour changes of the usual indicators would... 

A three-step nitration process of toluene is described. The advantages of the modified process are reduced waste, less hazardous operation, reduced oleum requirement, partial replacement of coned HN03 with dil HN03, and higher rate of toluene flow into the reactor (Ref 86) The continuous process of H.C. Prime (Ref 73) for preparing TNT was studied by thin-layer chromatography on silica gel with a starch binder and a fluorescent indicator. The nitration... 

Popova and colleagues47 carried out TLC of oxidation products of 4,4 -dinitrodiphenyl sulphide (the sulphoxide and sulphone) on silica gel + a fluorescent indicator, using hexane-acetone-benzene-methanol(60 36 10 l) as solvent mixture. Morris130 performed GLC and TLC of dimethyl sulphoxide. For the latter, he applied a 6% solution of the sample in methanol to silica gel and developed with methanol-ammonia solution(200 3), visualizing with 2% aqueous Co11 thiocyanate-methanol(2 1). HPLC separations of chiral mixtures of sulphoxides have been carried out. Thus Pirkle and coworkers131-132 reported separations of alkyl 2,4-dinitrophenyl sulphoxides and some others on a silica-gel (Porosil)-bonded chiral fluoroalcoholic stationary phase, with the structure ... 

Since the literature cited did not reveal a significant effect of the differing pore systems of the various types of layer the aluminium oxide and silica gel types (60, 80, 100, etc.) are not specified. The same applies to binders, fluorescence indicators and trace impurities in the sorbents. 

The detection limits for primary and secondary amines and for the amides are 10 to 60 ng substance per chromatogram zone [1]. The detection limits on layers with fluorescence indicators are about double the amount of substance [1]. 

The blue derivatives formed with the reagent by alkaloids remain stable for at least one day and usually much longer (cover the chromatogram with a glass plate) [2, 6, 7]. The shade of color produced can be affected by fluorescence indicators incorporated in the silica gel layer [7]. Tertiary amine alkaloids do not react at room temperature with the acetaldehyde-containing reagent [2]. 

Brief exposure to nitrous fumes (up to 3 min) leaves the fluorescent power of the acid-instable fluorescence indicator 254. incorporated into most TLC layers, largely unaffected, so that the nitroaromatics so formed can be detected as dark zones on a green fluorescent background [1]. For purposes of in situ quantitation it is recommended that the fluorescence indicator be destroyed by 10 min exposure to nitrous fumes in order to avoid difficulties in the subsequent evaluation [1]. 

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