Fluorescence exposure

Accel, fluorescent Exposure time Total exposure Room fluorescent Exposure time Total exposure Xenon... 

Use UVB fluorescent exposure as a primary method for screening formulations for weatherability (with a special focus on color fade and chalking), since the UVB attack on the acrylic component will mimic what happens outdoors at long times. 

LIF is also used witii liquid and solid samples. For example, LIF is used to detect lJO ions in minerals the uranyl ion is responsible for the bright green fluorescence given off by minerals such as autunite and opal upon exposure to UV light [23],... 

Sometimes a darker material forms that bleaches on further exposure to the incident light. In any case, reasonable stabiUty to light is one of the most important requisites of a useful fluorescent pigment, but the most difficult to achieve. An interesting discussion of the products of photolysis of 4-methyl-7-diethylaminocoumarin [91-44-1] is given in Reference 19. 

Whereas the eadiest fluorescent-dye pigments would last only 20 days outdoors in a screen-ink film, fade resistance has been improved to such an extent that some modem daylight-fluorescent coated panels stiU have useful color after nine months or mote in Florida sunlight in a 45° exposure tack facing south. The fluorescent layer is usually coated with an acrylic film containing a uv absorber. Indoor-accelerated exposure equipment is, of course, invaluable in the development of such systems. Better dyes and resins very likely will make possible fat mote stable coatings in the future. 

ASTM D4329, Practicefor OperatingEight- and Water-Exposure Apparatus (Fluorescent uv—Condensation Type) for Exposure of Plastics, Vol. 8.03, ASTM, Philadelphia, Pa., 1992. 

Ammonium sulfate triolein, oleic acid, androsten-3,17-dione, xanthanonic acid, cholesterol-propionate, N-methy Ipheny lalanine, D-glucose fluorescence after heating to 150 — 180 °C, exposure to tert-butyl hypochlorite [203]... 

The required exposure times are difficult to estimate. They are best found by trial and error. Documentation of fluorescence quenching at A = 254 nm usually only requires one trial. The exposure time found to be adequate here is normally suitable for all following exposures of fluorescence quenching if the exposure conditions are maintained constant (camera type, film type, distance of objective and lamp, aperture etc.). The exposure time required for fluorescent chromatograms is primarily dependent on the intensity of the fluorescence and, therefore, has to be optimized for each chromatogram. It is best to operate with a range of exposure times, e.g. aperture 8 with exposures of 15,30,60,120 and 240 seconds. Experience has shown that one exposure is always optimal. 

Aminoglycoside antibiotics and / -substituted indoles are stained red. Pyrrole derivatives with free / -positions react at room temperature to yield blue-colored zones [11]. Exposure to the vapors of aqua regia deepens the colors. This reaction sometimes produces fluorescence [3]. The detection limit for monomethylhydrazine is 200 pg per chromatogram zone [3]. 

Chelerythrine crystallises from alcohol in colourless, prismatic leaflets, m.p. 207°, containing one molecule of alcohol. The alkaloid absorbs carbon dioxide from the air, becoming yellow. The solutions fluoresce blue when the alkaloid is contaminated with its oxidation product, which is formed by mere exposure of solutions to air. The salts, which are quaternary, are intensely yellow. The hydrochloride, B. HCl. HjO, forms citron-yellow needles, and the sulphate, B. H2SO4.2HjO, golden-yellow needles, sparingly soluble in water the platinichloride, B2. HaPtCl. ... 

Materials and Techniques. The tanks and chambers for treatments 1, 3 and 4 were constructed of 3/16-inch-thick OP-4 Plexiglas those for treatment 2 were constructed of iM-inch-thick OP-2 Plexiglas. Mylar D (thickness 4 mils) was placed over the top of treatment tank 3 to reduce levels of ambient UV-B. Transmission spectra of these materials are shown in Fig. 3. Enhancement of UV-A and UV-B was achieved by placing four FS-20 Westinghouse fluorescent sunlamps underneath treatment tank 4. In order to exclude most of the radiation less than 290 nm wavelength emitted by the lamps, a sheet of 4 mils thick Kodacel (TA 401), which had been preconditioned by exposure to a sunlamp for approximately 100 hours, was placed between the sunlamps and the bottom of the enhanced UV tank. 

Luminescence measurements on proteins occupy a large part of the biochemical literature. In what surely was one of the earliest scientific reports of protein photoluminescence uncomplicated by concurrent insect or microorganism luminescence, Beccari (64), in 1746, detected a visible blue phosphorescence from chilled hands when they were brought into a dark room after exposure to sunlight. Stokes (10) remarked that the dark (ultraviolet) portion of the solar spectrum was most efficient in generating fluorescent emission and identified fluorescence from animal matter in 1852. In general, intrinsic protein fluorescence predominantly occurs between 300 nm and 400 nm and is very difficult to detect visually. The first... 

The dosimeter can detect various polynuclear aromatics at the pph level after 1 hour of exposure. It has been shown that the RTF of aza-arenes can he enhanced by using mercury(II) chloride as a heavy atom (21). Also, sensitized fluorescence spectrometry with a solid organic substrate can be used to detect trace amounts of polynuclear aromatic compounds (22). 

In situ quantitation The fading of the fluorescence on exposure to heat and on allowing the chromatograms to stand makes this reagent unsuitable for in situ quantitation. Dipping the chromatograms in paraffin solution does not improve this (Fig. 2). 

Exposure of rhodamine 6G-impregnated silica gel layers to iodine vapor for two to five minutes followed by irradiation with UV light leads to the sensitive blue coloration of the chromatogram zones on a greenish fluorescent background [8, 10]. 

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]. 

Variously colored chromatogram zones (grey, blue, brown, orange, violet) are pr K duced on a pale background the zones frequently fluoresce intensely on exposure to long-wavelength UV light (X = 365 nm). ... 

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