Clark, Violet

Costus Root Oil occurs as a light yellow to brown, viscous liquid with a peculiar, persistent odor reminiscent of violet, orris, and vetivert. It is the volatile oil obtained by steam distillation from the dried, triturated roots of the herbaceous perennial plant Saussurea lappa Clarke (Fam. Compositae) or by a solvent extraction procedure followed by vacuum distillation of the resinoid extract. It is soluble in most fixed... 

Analysis. The amine oxide picrates were determined according to the procedure of Clark and Wang. A sample of 0.2 to 0.4 meq. of the picrate was dissolved in 10 ml. of glacial acetic acid. About 3 drops of methyl violet indicator were used. The color change from deep to light blue was used as the end point. The solutions were titrated with standard O.IV perchloric acid in glacial acetic acid with a microburet. 

Symptoms of excess Mo in sorghum leaves appear as a dark violet coloration of the whole lamina and are distinguishable from the symptoms of phosphorus deficiency, which result in dark green leaves with overtones of dark red coloration (Clark, 1993). 

Adsorbent materials are used medicinally to absorb toxins in vivo. The enterotoxin of Pseudomonas aeruginosa is implicated in the aetiology of diarrhoea adsorbents such as kaolin are used to decrease the toxicity of such agents by removal of the toxin by adsorption. Armstrong and Clarke have investigated the adsorption sites on kaolin by measurement of electrophoretic mobility in the presence of surfactants and other materials as a function of pH [58]. In particular they studied the uptake of gentian violet on to koalin treated with anionic and cationic agents. Kaolin pretreated with cetrimide showed a marked decrease in adsorptive capacity. On the other hand, when pretreated with sodium hexadecyl sulphate the adsorptive capacity was increased (Fig. 9.22). 

Figure 9.22 Variation with pH of the uptake of a 0.05 % (w/v) solution of Gentian Violet on natural kaolin and on kaolin treated with anionic and cationic materials. Kaolin, pH 7.4 ( >) and 5.7 ( ) washed kaolin, pH 7.4 (V) and 5.4 ( ) kaolin plus sodium hexadecyl sulphate, pH 7.5 (O) and 5.6 ( ) and kaolin plus cetrimide, pH 7.6 (A) and 5.4 (A). From Armstrong and Clarke [58] with permission.

Reddish blue (Cl Blue 29), pink (Cl Red 259), and violet (Cl Violet 15) shades can be produced. Cl Blue 29 has FDA sanction for indirect food contact, and is widely used in cosmetics (ASTM D262). Most manufacture has shifted away from North America and Western Europe. Suppliers include Mineral Pigment Solutions Inc. (MPSI), formerly Whittaker, Clark and Daniels Holiday Pigments, trade name Artizan Habich GmbH Nubiola (Barcelona) and PD Industries and Ultramarine Pigments Ltd of India. 

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