Carmine chemistry

Comoli, Alfred G. Battista, Carmine A. Johanson, Edwin S. Laird, Carol P., "Development and Demonstration of the H-Coal Process," paper presented at the Division of Petroleum Chemistry, American Chemical Society Meeting, Miami,... 

Analytical chemistry of the alkalis is difficult. There are a few complex reagents that will precipitate with ions like Na+ and K+, but the reactions are best done using ether or alcohol as the solvent in place of water. It is more common to detect the presence of alkali metals in solutions or compounds by the characteristic colors the alkali metal ions impart to flames. In descending order, lithium salts give a carmine color, sodium salts a yellow color, potassium a violet color, rubidium a bluish red color, and cesium a blue color. 

Cochineal extract (Colour Index 75470, E 120)is the final alcohol-free material obtained after aqueous ethanolic extraction of the dried bodies of the female scale insect Dactylopius coccus Costa which lives on cacti such as Opuntia or Nopalea coccinellifera a species indigenous to Peru and Mexico, although also found in the Canary Islands. In practice a simpler procedure consists of aqueous alkaline extraction. The colourant principle is carminic acid which is more well-known in the form of carmine, an aluminium chelate of carminic acid, a material insoluble in water and stable on the acidic side. A uv spectrophotometric study has been made (ref. 21). Thin layer chromatography of cochineal has been examined on acetylated cellulose with the solvent system, ethyl acetate-tetrahydrofuran-water (6 35 47) in which the Rf was 0.94 (refs.22,23). The history of the chemistry of cochineal has been discussed (ref.24). 

Oxide-based Systems at the Crossroads of Chemistry , edited by Aldo Gamba, Carmine Colella and Salvatore Coluccia. 

Capacchione, Carmine D Acunzi, Maria Motta, Oriana Oliva, Leone Proto, Antonio Okuda, Jun., Macromolecular Chemistry and Physics, 2004,205, 370-373... 

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