Fluorescent colorants

Sulfonation increases the water solubiUty of dyes. A sulfonic group is electron withdrawing but has a weakening effect on the fluorescence only if it is ortho to the donor group. For example, in Brilliant Sulfoflavine FF [2391-30-2] (17), where R = p-tolyl, —it has a weakening effect, although the cleanness of the fluorescent color is somewhat improved compared to that of the unsulfonated compound. 

The total world marketplace can vary widely from year to year, however, due to the cyclic nature of the textile and coUateral appHcations which can be sizable but short-lived. Perhaps this is the reason that there are no published estimates for the world market for fluorescent color. Also, competition has forced most producers to develop higher strength fluorescent materials that offer greater color yield and a better money value. This reduces unit volume and, in many cases, doUar sales. 

Note The natural fluorescence colors of some flavonoids [7, 9] and anthracene derivatives [16] are altered by the ammonia treatment. This makes possible differentiation on the basis of color. Detection limits per chromatogram zone have been reported of 2 ng for morphine and heroin [2], 6 ng for ochratoxin A [5] and 1 pg for penicillic acid [13]. 

Fluorescenz, Fluoreszenz, /. fluorescence, fluoreszenzerzeugend, a. fluorogenic. Fluoreszenz-farbe, /. fluorescence color luminous paint, -messer, m. fluorometer. fluorescieren, fluoreszieren, v.t. fluoresce. — fluoreszierend, p.a. fluorescent. 

The fluorescence color converter technique [32] can, in principle, overcome much of this power loss by replacing the white light emitter with a blue-emitting organic stack, and the absorbing filters with green and red fluorescent dyes. Thus when a green pixel is desired, the OLED underneath is turned on and the blui... 

Acridine orange changes its fluorescence color from pale yellow-green to yellow in a specific pH range (pH 8-10) [1, 4]. 

Table 1 Fluorescence colors of the chromatogram zones and of the layer background as a function of the reagent employed and of the excitation wavelength [1],...

Dible 1 Fluorescence color and detection limits of the derivatives formed by reaction with various reagents incorporating chloramine T. 

Fluorescence colors produced on excitation at X = 365 nm detection limits in ng per chromatogram zone, after dipping in liquid paraffin - n-hexane (1+2). 

For instance, trenbolone fluoresces yellow [12] and the qinoxalone derivative of pyruvic acid yellow-green [18]. In the case of steroids and Digitalis glycosides it is possible to differentiate on the basis of various fluorescence colors [8, 9, 15]. 

In daylight the nitrophenols appeared as variously colored chromatogram zones on a pale yellow background, under long-wavelength UV light (X = 365 nm) they were et-cited to the emission of fluorescence. The associated hRj values, colors and fluorescence colors are listed in the table below ... 

Acridine orange, pH-dependent change of fluorescence color 91 Activation of the layer 124ff. N-Acylglycine conjugates 176 ADB = 2-amino-2, 5-dichlorobenzophe-none 227... 

Quercitrin 149, 279, 280, 323 Quinaldic acid 171 Quinine alkaloids 88 Quinine, pH-dependent change of fluorescence color 91 Quinoline alkaloids 66... 

Umbelliferone, pH-dependent change of fluorescence color 44 Universal reagents 4,46,195,376,402,405, 412, 430, 434 Uracil derivatives 44,45 Uranium cations 144 Uranyl acetate reagent 44 Urea... 

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