Blue/UV light

An improvement to this technique will be to use a continuous blue/UV light source and replacing the PMT by a compact spectrometer coupled to a CCD (charge-coupled device) for readout, thus accelerating the data acquisition. In the latter case, the scanning and evaluation takes a few milliseconds. 

Oelmiiller R, Mohr H. 1985. Mode of co-action between blue/UV light and light absorbed by phytochrome in light-mediated anthocyanin formation in the milo (Sorghum vulgare Pers.) seedling, Proc Natl Acad Sci USA 82 6124-6128. 

Twenty-two polished thin sections were examined with a Technosyn cathodo-luminoscope at an acceleration voltage of 12-15 kV and a beam current intensity of 0.42-0.43 mA, and under blue UV light in an Olympus BX60 microscope with 100 W... 

Kuo, J. S., Kuyper, C. L., Allen, P. B., Fiorini, G. S., and Chiu, D. T., High-power blue/UV light-emitting diodes as excitation sources for sensitive detection. Electrophoresis, 25, 3796, 2004. 

After the dipped or sprayed chromatogram has been dried in a stream of cold air long-wave UV light (2 = 365 nm) reveals fluorescent yellow zones (flavonoids). Sterigmatocystine, which can be detected without derivatization on account of its red intrinsic fluorescence (detection limit 0.5 pg), also fluoresces pale yellow after being heated to 80°C [9] or 100°C [13] for 10 min on the other hand, citrinine, zearalenone and vomitoxin fluoresce blue. 

The chromatogram is freed from mobile phase and immersed for 1 s in the freshly prepared reagent solution and then heated to 105 to 110 °C for 5 to 10 min. Green, blue or purple fluorescence appears on a dark background under long-wavelength UV light (2 = 365 nm). 

Grey-green zones on a white background resulted they exhibited weak red fluorescence under long-wavelength UV light (X = 365 nm) glucose and fructose exhibited pale blue fluorescence in method B. Some hRf values are listed in Table 1. 

Fig. 1 Separation of the corticosteroids. (A) Detection in UV light (A = 254 nm, (B) staining with blue tetrazolium. Tetrahydrocortisol (1), tetrahydrocortisone (2), prednisolone (3), hydrocortisone (4), prednisone (5), cortisone (6), corticosterone (7), cortexolone (8), 11-dehydrocorticosterone (9), 11-desoxycorticosterone (10), mixture (Mi),...

In long-wavelength UV light (2 = 365 nm) carbohydrates, e.g. glucose, fructose and lactose, yield pale blue fluorescent derivatives on a weakly fluorescent background. In situ quantitation can be performed at = 365 nm and 2fi = 546 nm (monochromatic filter M 546) [19]. Further differentiation can be achieved by spraying afterwards with p-anisidine-phosphoric acid reagent [8]. 

After evaporation of the hexane blue fluorescent chromatogram zones are visible on a dark background under long-wavelength UV light (1 = 365 nm). 

Note The alternative fast blue salt BB produced the most intensely colored chromatogram zones for visual analysis in daylight, while fluorescence quenching in UV light (A = 254 nm) was greater with fast blue salt B and fast blue salt RR (Figs. 1 and 2). 

The digitalis glycosides yielded blue fluorescent zones in long- wavelength UV light (A = 365 nm) (Fig. 1). 

Detection and result The chromatograms were freed from mobile phase (stream of cold air), immersed in the reagent solution for 20 s, then dried in the air and finally kept at room temperature for 20 min. Testosterone (hRf 35—40) fluoresced pale blue in long-wavelength UV light (2 = 365 nm. Fig. 1). 

Note The reaction for barbiturates according to variant I is increased in sensitivity if the chromatogram is exposed to direct sunlight or UV light after it has been sprayed this causes the background coloration to fade almost completely and the blue zones stand out more distinctly [4]. 

Substance zones are produced that mainly yield blue fluorescence under long-wavelength UV light (A = 365nm) (indoles occasionally fluoresce yellow [15]), colored zones are also produced occasionally. The fluorescence is stabilized by immersing in 20% methanohc polyethylene glycol solution [5]. 

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