Normalized absorbance, different dyes

Figure 17-d. Comparison of normalized absorbance for different dyes. TB Thymol Blue BPB Bromophenol Blue BCG Bromocresol Green NR Neutral Red BTB Bromothymol Blue PR Phenol Red PP phenolphthalein. (a) Passive optodes (b) optode with Amberlite XAD-4 without membrane (configuration as in Figure 17-3 c). 

Do not stain the spots too strongly because if the the amount of absorbed bromophenol blue is too high, some of this dye could be incorporated in the peptide. In that case removal of the color is almost impossible and could affect the detection. Because bromophenol blue has a blue color in a basic environment, e.g., primary amino functions, a difference in the intensity of the color of the spots is normal due to different acidity of the coupled amino acids. 

The polarities of different solvents can be compared using fluorescence probe molecules or solvatochromic dyes. When such molecules are dissolved in a solvent, the frequency of the maximum fluorescence or absorption, respectively, changes as a function of the polarity of the medium, and this property can then be compared with the result for standard solvents. The polarities of several ionic liquids were estimated using 5-dimethylamino-isoindole-l,3-dione 34 as a fluorescence probe and Reichardt s dye 35 for visible absorbance measurements, allowing the determination of the normalized parameter ( . (tetramethylsilane) = 0,... 

The two major types of colorants produced today are dyestuffs and pigments. The difference between these products is evident from the definitions a dyestuff is normally a water-soluble or water-dispersible compound that, is capable of being absorbed into the substrate, whereas a pigment is normally a water-insoluble compound that requires a binder or is entrapped within the matrix of the substrate. The majority of pigments are soluble in solvents and plastics, and both dyes and pigments impart very high tinctorial value for the amount used to color a product. The major end use for dyes is in the textile, leather, and paper industries. Pigments find major uses in paint, ink, and plastic industries. 

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