Natural pigments solvent

Organic modifiers have been frequently employed in CE to increase the solubility of hydrophobic solutes in the aqueous buffer system. Unfortunately, many organic modifiers are UV absorbent and cannot be used without considerable loss of sensitivity of detection. A contactless conductivity detection system has been developed which extends the application range of UV-absorbing solvents [ 119]. As both natural pigments and synthetic dyes absorb in the visible part of the spectra, the application of UV-absorbing organic modifiers in their CE analysis does not cause detection problems. 

Considerable attention has been devoted to the behavior of band I upon protonation of the Schiff base. The main new features are a substantial red shift (to, e.g., 440 nm in hydrocarbon solvents), and a very high solvent sensitivity. The red shift is readily predicted by theory in terms of stabilization of the lowest state due to the increase in electron delocalization (i.e., decrease in bond alternation) upon protonation (122— 125). However, two complex problems are obviously present which are relevant to the spectroscopy of natural pigments (1) the substantial blue shift between the theoretically predicted (123, 125) maximum absorption of a free protonated Schiff base in the gas phase (A jj = 600 nm) and that observed in solution (A, ... 

Standard Test Method for Quahtative Determination of Nature of Solvent Composition in Solvent-Reducible Paints Standard Test Method for Antimony Oxide in White Pigment Separated from Solvent-Reducible Paints Standard Test Method for Sulfide in White Pigment Separated from Solvent-Reducible Paints... 

Photometric detection, 208-210 Photomultipliers, 378-379 Physical methods of detection, 206-211 photometric detection, 208-210 visual detection, 206-208 Physical phenomena in TLC, 49-53 broadening of chromatographic spots, 50-53 capillary flow, 49-50 volatility of solvents, 53 Pigments. See Natural pigments Planar chromatography (instrumental TLC), 3, 129-148,373-385 automation in, 131,382-384 chromatogram development, 135-140 automated multiple development (AMD), 138-140... 

Electrostatic i. Photocopying machines need toners based on resins (- resins, natural)/pigment mixtures, which have the property to deposit electrostatically on an image and form a homogenous film by heat or solvent exposure. 

Phthalocyanine Dyes. In addition to their use as pigments, the phthalocyanines have found widespread appHcation as dyestuffs, eg, direct and reactive dyes, water-soluble dyes with physical or chemical binding, solvent-soluble dyes with physical or chemical binding, a2o reactive dyes, a2o nonreactive dyes, sulfur dyes, and wet dyes. The first phthalocyanine dyes were used in the early 1930s to dye textiles like cotton (qv). The water-soluble forms Hke sodium salts of copper phthalocyanine disulfonic acid. Direct Blue 86 [1330-38-7] (Cl 74180), Direct Blue 87 [1330-39-8] (Cl 74200), Acid Blue 249 [36485-85-5] (Cl 74220), and their derivatives are used to dye natural and synthetic textiles (qv), paper, and leather (qv). The sodium salt of cobalt phthalocyanine, ie. Vat Blue 29 [1328-50-3] (Cl 74140) is mostly appHed to ceUulose fibers (qv). 

Because these pigments are organic in nature they tend to bleed in resins and solvents. Increasing the molecular weight often reduces this tendency. For this reason, LG. Farbenindustrie introduced a line of pigments based on Naphthol AS as the coupling component, eg. Permanent Bordeaux FRR... 

Oxidized castor oils are excellent nonmigrating, nonvolatile plasticizers (qv) for ceUulosic resins, poly(vinyl butyral), polyamides, shellac, and natural and synthetic mbber (see Rubber, natural). The high viscosity products are also used as tackifiers in gasket compounds and adhesives (qv) because of good oil and solvent resistance. They also serve as excellent pigment grinding media and as a base for inks (qv), lubricating oils, and hydrauHc oils (62). 

Betalains are vacuolar plant pigments. Hence their hydrophilic nature is comprehensible. Although they are slightly soluble in ethanol and methanol, water is the best snited solvent both for stability and solnbility reasons. In contrast to the antho-cyanins, the betalains are even more polar as can be demonstrated by shorter retention times in RP-HPLC and lower solubilities in alcoholic solutions. The varying polarities may also be beneficially used to separate anthocyanins from betalains on an RP-18 solid-phase extraction cartridge (Stintzing, unpublished data). 

---